vulkan-example.c

#define _GNU_SOURCE
#include <assert.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "linmath.h"
#include "object_type_string_helper.h"
#include <vulkan/vulkan.h>

#include "gettime.h"
#include "inttypes.h"
#define MILLION 1000000L
#define BILLION 1000000000L

#define DEMO_TEXTURE_COUNT 1
#define APP_SHORT_NAME "vkcube"
#define APP_LONG_NAME "Vulkan Cube"

// Allow a maximum of two outstanding presentation operations.
#define FRAME_LAG 2

#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))

/*
 * structure to track all objects related to a texture.
 */
struct texture_object
{
    VkSampler sampler;

    VkImage image;
    VkBuffer buffer;
    VkImageLayout imageLayout;

    VkMemoryAllocateInfo mem_alloc;
    VkDeviceMemory mem;
    VkImageView view;
    int32_t tex_width, tex_height;
};

static char* tex_files[] = { "lunarg.ppm" };

static int validation_error = 0;

struct vktexcube_vs_uniform
{
    // Must start with MVP
    float mvp[4][4];
    float position[12 * 3][4];
    float attr[12 * 3][4];
};

//--------------------------------------------------------------------------------------
// Mesh and VertexFormat Data
//--------------------------------------------------------------------------------------
// clang-format off
static const float g_vertex_buffer_data[] = {
    -1.0f,-1.0f,-1.0f,  // -X side
    -1.0f,-1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,

    -1.0f,-1.0f,-1.0f,  // -Z side
     1.0f, 1.0f,-1.0f,
     1.0f,-1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f, 1.0f,-1.0f,
     1.0f, 1.0f,-1.0f,

    -1.0f,-1.0f,-1.0f,  // -Y side
     1.0f,-1.0f,-1.0f,
     1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f,-1.0f,
     1.0f,-1.0f, 1.0f,
    -1.0f,-1.0f, 1.0f,

    -1.0f, 1.0f,-1.0f,  // +Y side
    -1.0f, 1.0f, 1.0f,
     1.0f, 1.0f, 1.0f,
    -1.0f, 1.0f,-1.0f,
     1.0f, 1.0f, 1.0f,
     1.0f, 1.0f,-1.0f,

     1.0f, 1.0f,-1.0f,  // +X side
     1.0f, 1.0f, 1.0f,
     1.0f,-1.0f, 1.0f,
     1.0f,-1.0f, 1.0f,
     1.0f,-1.0f,-1.0f,
     1.0f, 1.0f,-1.0f,

    -1.0f, 1.0f, 1.0f,  // +Z side
    -1.0f,-1.0f, 1.0f,
     1.0f, 1.0f, 1.0f,
    -1.0f,-1.0f, 1.0f,
     1.0f,-1.0f, 1.0f,
     1.0f, 1.0f, 1.0f,
};

static const float g_uv_buffer_data[] = {
    0.0f, 1.0f,  // -X side
    1.0f, 1.0f,
    1.0f, 0.0f,
    1.0f, 0.0f,
    0.0f, 0.0f,
    0.0f, 1.0f,

    1.0f, 1.0f,  // -Z side
    0.0f, 0.0f,
    0.0f, 1.0f,
    1.0f, 1.0f,
    1.0f, 0.0f,
    0.0f, 0.0f,

    1.0f, 0.0f,  // -Y side
    1.0f, 1.0f,
    0.0f, 1.0f,
    1.0f, 0.0f,
    0.0f, 1.0f,
    0.0f, 0.0f,

    1.0f, 0.0f,  // +Y side
    0.0f, 0.0f,
    0.0f, 1.0f,
    1.0f, 0.0f,
    0.0f, 1.0f,
    1.0f, 1.0f,

    1.0f, 0.0f,  // +X side
    0.0f, 0.0f,
    0.0f, 1.0f,
    0.0f, 1.0f,
    1.0f, 1.0f,
    1.0f, 0.0f,

    0.0f, 0.0f,  // +Z side
    0.0f, 1.0f,
    1.0f, 0.0f,
    0.0f, 1.0f,
    1.0f, 1.0f,
    1.0f, 0.0f,
};
// clang-format on

typedef struct
{
    VkImage image;
    VkCommandBuffer cmd;
    VkCommandBuffer graphics_to_present_cmd;
    VkImageView view;
    VkBuffer uniform_buffer;
    VkDeviceMemory uniform_memory;
    VkFramebuffer framebuffer;
    VkDescriptorSet descriptor_set;
} SwapchainImageResources;

struct demo
{
    VkSurfaceKHR surface;
    bool prepared;
    bool use_staging_buffer;
    bool separate_present_queue;
    bool is_minimized;

    VkInstance inst;
    VkPhysicalDevice gpu;
    VkDevice device;
    VkQueue graphics_queue;
    VkQueue present_queue;
    uint32_t graphics_queue_family_index;
    uint32_t present_queue_family_index;
    VkSemaphore image_acquired_semaphores[FRAME_LAG];
    VkSemaphore draw_complete_semaphores[FRAME_LAG];
    VkSemaphore image_ownership_semaphores[FRAME_LAG];
    VkPhysicalDeviceProperties gpu_props;
    VkQueueFamilyProperties* queue_props;
    VkPhysicalDeviceMemoryProperties memory_properties;

    uint32_t enabled_extension_count;
    uint32_t enabled_layer_count;
    char* extension_names[64];
    char* enabled_layers[64];

    int width, height;
    VkFormat format;
    VkColorSpaceKHR color_space;

    uint32_t swapchainImageCount;
    VkSwapchainKHR swapchain;
    SwapchainImageResources* swapchain_image_resources;
    VkPresentModeKHR presentMode;
    VkFence fences[FRAME_LAG];
    int frame_index;

    VkCommandPool cmd_pool;
    VkCommandPool present_cmd_pool;

    struct
    {
        VkFormat format;

        VkImage image;
        VkMemoryAllocateInfo mem_alloc;
        VkDeviceMemory mem;
        VkImageView view;
    } depth;

    struct texture_object textures[DEMO_TEXTURE_COUNT];
    struct texture_object staging_texture;

    VkCommandBuffer cmd; // Buffer for initialization commands
    VkPipelineLayout pipeline_layout;
    VkDescriptorSetLayout desc_layout;
    VkPipelineCache pipelineCache;
    VkRenderPass render_pass;
    VkPipeline pipeline;

    mat4x4 projection_matrix;
    mat4x4 view_matrix;
    mat4x4 model_matrix;

    float spin_angle;
    float spin_increment;
    bool pause;

    VkShaderModule vert_shader_module;
    VkShaderModule frag_shader_module;

    VkDescriptorPool desc_pool;

    bool quit;
    bool validate;
    bool validate_checks_disabled;
    bool use_break;
    bool suppress_popups;

    uint32_t current_buffer;
    uint32_t queue_family_count;
};

// Forward declaration:
static void
demo_resize(struct demo* demo);

static bool
memory_type_from_properties(struct demo* demo, uint32_t typeBits, VkFlags requirements_mask,
                            uint32_t* typeIndex)
{
    // Search memtypes to find first index with those properties
    for (uint32_t i = 0; i < VK_MAX_MEMORY_TYPES; i++) {
        if ((typeBits & 1) == 1) {
            // Type is available, does it match user properties?
            if ((demo->memory_properties.memoryTypes[i].propertyFlags & requirements_mask) ==
                requirements_mask) {
                *typeIndex = i;
                return true;
            }
        }
        typeBits >>= 1;
    }
    // No memory types matched, return failure
    return false;
}

static void
demo_flush_init_cmd(struct demo* demo)
{
    VkResult U_ASSERT_ONLY err;

    // This function could get called twice if the texture uses a staging buffer
    // In that case the second call should be ignored
    if (demo->cmd == VK_NULL_HANDLE)
        return;

    err = vkEndCommandBuffer(demo->cmd);
    assert(!err);

    VkFence fence;
    VkFenceCreateInfo fence_ci = { .sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO, .pNext = NULL, .flags = 0 };
    err = vkCreateFence(demo->device, &fence_ci, NULL, &fence);
    assert(!err);

    const VkCommandBuffer cmd_bufs[] = { demo->cmd };
    VkSubmitInfo submit_info = { .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
                                 .pNext = NULL,
                                 .waitSemaphoreCount = 0,
                                 .pWaitSemaphores = NULL,
                                 .pWaitDstStageMask = NULL,
                                 .commandBufferCount = 1,
                                 .pCommandBuffers = cmd_bufs,
                                 .signalSemaphoreCount = 0,
                                 .pSignalSemaphores = NULL };

    err = vkQueueSubmit(demo->graphics_queue, 1, &submit_info, fence);
    assert(!err);

    err = vkWaitForFences(demo->device, 1, &fence, VK_TRUE, UINT64_MAX);
    assert(!err);

    vkFreeCommandBuffers(demo->device, demo->cmd_pool, 1, cmd_bufs);
    vkDestroyFence(demo->device, fence, NULL);
    demo->cmd = VK_NULL_HANDLE;
}

static void
demo_set_image_layout(struct demo* demo, VkImage image, VkImageAspectFlags aspectMask,
                      VkImageLayout old_image_layout, VkImageLayout new_image_layout,
                      VkAccessFlagBits srcAccessMask, VkPipelineStageFlags src_stages,
                      VkPipelineStageFlags dest_stages)
{
    assert(demo->cmd);

    VkImageMemoryBarrier image_memory_barrier = { .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
                                                  .pNext = NULL,
                                                  .srcAccessMask = srcAccessMask,
                                                  .dstAccessMask = 0,
                                                  .srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
                                                  .dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED,
                                                  .oldLayout = old_image_layout,
                                                  .newLayout = new_image_layout,
                                                  .image = image,
                                                  .subresourceRange = { aspectMask, 0, 1, 0, 1 } };

    switch (new_image_layout) {
        case VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL:
            /* Make sure anything that was copying from this image has completed */
            image_memory_barrier.dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
            break;

        case VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL:
            image_memory_barrier.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
            break;

        case VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL:
            image_memory_barrier.dstAccessMask = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;
            break;

        case VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL:
            image_memory_barrier.dstAccessMask =
                VK_ACCESS_SHADER_READ_BIT | VK_ACCESS_INPUT_ATTACHMENT_READ_BIT;
            break;

        case VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL:
            image_memory_barrier.dstAccessMask = VK_ACCESS_TRANSFER_READ_BIT;
            break;

        case VK_IMAGE_LAYOUT_PRESENT_SRC_KHR:
            image_memory_barrier.dstAccessMask = VK_ACCESS_MEMORY_READ_BIT;
            break;

        default:
            image_memory_barrier.dstAccessMask = 0;
            break;
    }

    VkImageMemoryBarrier* pmemory_barrier = &image_memory_barrier;

    vkCmdPipelineBarrier(demo->cmd, src_stages, dest_stages, 0, 0, NULL, 0, NULL, 1, pmemory_barrier);
}

static void
demo_draw_build_cmd(struct demo* demo, VkCommandBuffer cmd_buf)
{
    VkDebugUtilsLabelEXT label;
    memset(&label, 0, sizeof(label));
    const VkCommandBufferBeginInfo cmd_buf_info = {
        .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
        .pNext = NULL,
        .flags = VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT,
        .pInheritanceInfo = NULL,
    };
    const VkClearValue clear_values[2] = {
        [0] = { .color.float32 = { 0.2f, 0.2f, 0.2f, 0.2f } },
        [1] = { .depthStencil = { 1.0f, 0 } },
    };
    const VkRenderPassBeginInfo rp_begin = {
        .sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO,
        .pNext = NULL,
        .renderPass = demo->render_pass,
        .framebuffer = demo->swapchain_image_resources[demo->current_buffer].framebuffer,
        .renderArea.offset.x = 0,
        .renderArea.offset.y = 0,
        .renderArea.extent.width = demo->width,
        .renderArea.extent.height = demo->height,
        .clearValueCount = 2,
        .pClearValues = clear_values,
    };
    VkResult U_ASSERT_ONLY err;

    err = vkBeginCommandBuffer(cmd_buf, &cmd_buf_info);

    if (demo->validate) {
        // Set a name for the command buffer
        VkDebugUtilsObjectNameInfoEXT cmd_buf_name = {
            .sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_OBJECT_NAME_INFO_EXT,
            .pNext = NULL,
            .objectType = VK_OBJECT_TYPE_COMMAND_BUFFER,
            .objectHandle = (uint64_t)cmd_buf,
            .pObjectName = "CubeDrawCommandBuf",
        };
        demo->SetDebugUtilsObjectNameEXT(demo->device, &cmd_buf_name);

        label.sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_LABEL_EXT;
        label.pNext = NULL;
        label.pLabelName = "DrawBegin";
        label.color[0] = 0.4f;
        label.color[1] = 0.3f;
        label.color[2] = 0.2f;
        label.color[3] = 0.1f;
        demo->CmdBeginDebugUtilsLabelEXT(cmd_buf, &label);
    }

    assert(!err);
    vkCmdBeginRenderPass(cmd_buf, &rp_begin, VK_SUBPASS_CONTENTS_INLINE);

    if (demo->validate) {
        label.sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_LABEL_EXT;
        label.pNext = NULL;
        label.pLabelName = "InsideRenderPass";
        label.color[0] = 8.4f;
        label.color[1] = 7.3f;
        label.color[2] = 6.2f;
        label.color[3] = 7.1f;
        demo->CmdBeginDebugUtilsLabelEXT(cmd_buf, &label);
    }

    vkCmdBindPipeline(cmd_buf, VK_PIPELINE_BIND_POINT_GRAPHICS, demo->pipeline);
    vkCmdBindDescriptorSets(cmd_buf, VK_PIPELINE_BIND_POINT_GRAPHICS, demo->pipeline_layout, 0, 1,
                            &demo->swapchain_image_resources[demo->current_buffer].descriptor_set, 0, NULL);
    VkViewport viewport;
    memset(&viewport, 0, sizeof(viewport));
    viewport.height = (float)demo->height;
    viewport.width = (float)demo->width;
    viewport.minDepth = (float)0.0f;
    viewport.maxDepth = (float)1.0f;
    vkCmdSetViewport(cmd_buf, 0, 1, &viewport);

    VkRect2D scissor;
    memset(&scissor, 0, sizeof(scissor));
    scissor.extent.width = demo->width;
    scissor.extent.height = demo->height;
    scissor.offset.x = 0;
    scissor.offset.y = 0;
    vkCmdSetScissor(cmd_buf, 0, 1, &scissor);

    if (demo->validate) {
        label.sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_LABEL_EXT;
        label.pNext = NULL;
        label.pLabelName = "ActualDraw";
        label.color[0] = -0.4f;
        label.color[1] = -0.3f;
        label.color[2] = -0.2f;
        label.color[3] = -0.1f;
        demo->CmdBeginDebugUtilsLabelEXT(cmd_buf, &label);
    }

    vkCmdDraw(cmd_buf, 12 * 3, 1, 0, 0);
    if (demo->validate) {
        demo->CmdEndDebugUtilsLabelEXT(cmd_buf);
    }

    // Note that ending the renderpass changes the image's layout from
    // COLOR_ATTACHMENT_OPTIMAL to PRESENT_SRC_KHR
    vkCmdEndRenderPass(cmd_buf);
    if (demo->validate) {
        demo->CmdEndDebugUtilsLabelEXT(cmd_buf);
    }

    if (demo->separate_present_queue) {
        // We have to transfer ownership from the graphics queue family to the
        // present queue family to be able to present.  Note that we don't have
        // to transfer from present queue family back to graphics queue family at
        // the start of the next frame because we don't care about the image's
        // contents at that point.
        VkImageMemoryBarrier image_ownership_barrier = {
            .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
            .pNext = NULL,
            .srcAccessMask = 0,
            .dstAccessMask = 0,
            .oldLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
            .newLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
            .srcQueueFamilyIndex = demo->graphics_queue_family_index,
            .dstQueueFamilyIndex = demo->present_queue_family_index,
            .image = demo->swapchain_image_resources[demo->current_buffer].image,
            .subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 }
        };

        vkCmdPipelineBarrier(cmd_buf, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT,
                             VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, 0, 0, NULL, 0, NULL, 1,
                             &image_ownership_barrier);
    }
    if (demo->validate) {
        demo->CmdEndDebugUtilsLabelEXT(cmd_buf);
    }
    err = vkEndCommandBuffer(cmd_buf);
    assert(!err);
}

void
demo_build_image_ownership_cmd(struct demo* demo, int i)
{
    VkResult U_ASSERT_ONLY err;

    const VkCommandBufferBeginInfo cmd_buf_info = {
        .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
        .pNext = NULL,
        .flags = VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT,
        .pInheritanceInfo = NULL,
    };
    err = vkBeginCommandBuffer(demo->swapchain_image_resources[i].graphics_to_present_cmd, &cmd_buf_info);
    assert(!err);

    VkImageMemoryBarrier image_ownership_barrier = { .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
                                                     .pNext = NULL,
                                                     .srcAccessMask = 0,
                                                     .dstAccessMask = 0,
                                                     .oldLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
                                                     .newLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
                                                     .srcQueueFamilyIndex = demo->graphics_queue_family_index,
                                                     .dstQueueFamilyIndex = demo->present_queue_family_index,
                                                     .image = demo->swapchain_image_resources[i].image,
                                                     .subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0,
                                                                           1 } };

    vkCmdPipelineBarrier(demo->swapchain_image_resources[i].graphics_to_present_cmd,
                         VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, 0, 0,
                         NULL, 0, NULL, 1, &image_ownership_barrier);
    err = vkEndCommandBuffer(demo->swapchain_image_resources[i].graphics_to_present_cmd);
    assert(!err);
}

void
demo_update_data_buffer(struct demo* demo)
{
    mat4x4 MVP, Model, VP;
    int matrixSize = sizeof(MVP);
    uint8_t* pData;
    VkResult U_ASSERT_ONLY err;

    mat4x4_mul(VP, demo->projection_matrix, demo->view_matrix);

    // Rotate around the Y axis
    mat4x4_dup(Model, demo->model_matrix);
    mat4x4_rotate(demo->model_matrix, Model, 0.0f, 1.0f, 0.0f, (float)degreesToRadians(demo->spin_angle));
    mat4x4_mul(MVP, VP, demo->model_matrix);

    err = vkMapMemory(demo->device, demo->swapchain_image_resources[demo->current_buffer].uniform_memory, 0,
                      VK_WHOLE_SIZE, 0, (void**)&pData);
    assert(!err);

    memcpy(pData, (const void*)&MVP[0][0], matrixSize);

    vkUnmapMemory(demo->device, demo->swapchain_image_resources[demo->current_buffer].uniform_memory);
}

static void
demo_draw(struct demo* demo)
{
    VkResult U_ASSERT_ONLY err;

    // Ensure no more than FRAME_LAG renderings are outstanding
    vkWaitForFences(demo->device, 1, &demo->fences[demo->frame_index], VK_TRUE, UINT64_MAX);
    vkResetFences(demo->device, 1, &demo->fences[demo->frame_index]);

    do {
        // Get the index of the next available swapchain image:
        err = vkAcquireNextImageKHR(demo->device, demo->swapchain, UINT64_MAX,
                                    demo->image_acquired_semaphores[demo->frame_index], VK_NULL_HANDLE,
                                    &demo->current_buffer);

        if (err == VK_ERROR_OUT_OF_DATE_KHR) {
            // demo->swapchain is out of date (e.g. the window was resized) and
            // must be recreated:
            demo_resize(demo);
        } else if (err == VK_SUBOPTIMAL_KHR) {
            // demo->swapchain is not as optimal as it could be, but the platform's
            // presentation engine will still present the image correctly.
            break;
        } else {
            assert(!err);
        }
    } while (err != VK_SUCCESS);

    demo_update_data_buffer(demo);

    // Wait for the image acquired semaphore to be signaled to ensure
    // that the image won't be rendered to until the presentation
    // engine has fully released ownership to the application, and it is
    // okay to render to the image.
    VkPipelineStageFlags pipe_stage_flags;
    VkSubmitInfo submit_info;
    submit_info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
    submit_info.pNext = NULL;
    submit_info.pWaitDstStageMask = &pipe_stage_flags;
    pipe_stage_flags = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
    submit_info.waitSemaphoreCount = 1;
    submit_info.pWaitSemaphores = &demo->image_acquired_semaphores[demo->frame_index];
    submit_info.commandBufferCount = 1;
    submit_info.pCommandBuffers = &demo->swapchain_image_resources[demo->current_buffer].cmd;
    submit_info.signalSemaphoreCount = 1;
    submit_info.pSignalSemaphores = &demo->draw_complete_semaphores[demo->frame_index];
    err = vkQueueSubmit(demo->graphics_queue, 1, &submit_info, demo->fences[demo->frame_index]);
    assert(!err);

    if (demo->separate_present_queue) {
        // If we are using separate queues, change image ownership to the
        // present queue before presenting, waiting for the draw complete
        // semaphore and signalling the ownership released semaphore when finished
        VkFence nullFence = VK_NULL_HANDLE;
        pipe_stage_flags = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
        submit_info.waitSemaphoreCount = 1;
        submit_info.pWaitSemaphores = &demo->draw_complete_semaphores[demo->frame_index];
        submit_info.commandBufferCount = 1;
        submit_info.pCommandBuffers =
            &demo->swapchain_image_resources[demo->current_buffer].graphics_to_present_cmd;
        submit_info.signalSemaphoreCount = 1;
        submit_info.pSignalSemaphores = &demo->image_ownership_semaphores[demo->frame_index];
        err = vkQueueSubmit(demo->present_queue, 1, &submit_info, nullFence);
        assert(!err);
    }

    // If we are using separate queues we have to wait for image ownership,
    // otherwise wait for draw complete
    VkPresentInfoKHR present = {
        .sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR,
        .pNext = NULL,
        .waitSemaphoreCount = 1,
        .pWaitSemaphores = (demo->separate_present_queue)
                               ? &demo->image_ownership_semaphores[demo->frame_index]
                               : &demo->draw_complete_semaphores[demo->frame_index],
        .swapchainCount = 1,
        .pSwapchains = &demo->swapchain,
        .pImageIndices = &demo->current_buffer,
    };

    VkRectLayerKHR rect;
    VkPresentRegionKHR region;
    VkPresentRegionsKHR regions;

    err = vkQueuePresentKHR(demo->present_queue, &present);
    demo->frame_index += 1;
    demo->frame_index %= FRAME_LAG;

    if (err == VK_ERROR_OUT_OF_DATE_KHR) {
        // demo->swapchain is out of date (e.g. the window was resized) and
        // must be recreated:
        demo_resize(demo);
    } else if (err == VK_SUBOPTIMAL_KHR) {
        // demo->swapchain is not as optimal as it could be, but the platform's
        // presentation engine will still present the image correctly.
    } else {
        assert(!err);
    }
}

static void
demo_prepare_buffers(struct demo* demo)
{
    VkResult U_ASSERT_ONLY err;
    VkSwapchainKHR oldSwapchain = demo->swapchain;

    // Check the surface capabilities and formats
    VkSurfaceCapabilitiesKHR surfCapabilities;
    err = vkGetPhysicalDeviceSurfaceCapabilitiesKHR(demo->gpu, demo->surface, &surfCapabilities);
    assert(!err);

    uint32_t presentModeCount;
    err = vkGetPhysicalDeviceSurfacePresentModesKHR(demo->gpu, demo->surface, &presentModeCount, NULL);
    assert(!err);
    VkPresentModeKHR* presentModes = (VkPresentModeKHR*)malloc(presentModeCount * sizeof(VkPresentModeKHR));
    assert(presentModes);
    err =
        vkGetPhysicalDeviceSurfacePresentModesKHR(demo->gpu, demo->surface, &presentModeCount, presentModes);
    assert(!err);

    VkExtent2D swapchainExtent;
    // width and height are either both 0xFFFFFFFF, or both not 0xFFFFFFFF.
    if (surfCapabilities.currentExtent.width == 0xFFFFFFFF) {
        // If the surface size is undefined, the size is set to the size
        // of the images requested, which must fit within the minimum and
        // maximum values.
        swapchainExtent.width = demo->width;
        swapchainExtent.height = demo->height;

        if (swapchainExtent.width < surfCapabilities.minImageExtent.width) {
            swapchainExtent.width = surfCapabilities.minImageExtent.width;
        } else if (swapchainExtent.width > surfCapabilities.maxImageExtent.width) {
            swapchainExtent.width = surfCapabilities.maxImageExtent.width;
        }

        if (swapchainExtent.height < surfCapabilities.minImageExtent.height) {
            swapchainExtent.height = surfCapabilities.minImageExtent.height;
        } else if (swapchainExtent.height > surfCapabilities.maxImageExtent.height) {
            swapchainExtent.height = surfCapabilities.maxImageExtent.height;
        }
    } else {
        // If the surface size is defined, the swap chain size must match
        swapchainExtent = surfCapabilities.currentExtent;
        demo->width = surfCapabilities.currentExtent.width;
        demo->height = surfCapabilities.currentExtent.height;
    }

    if (demo->width == 0 || demo->height == 0) {
        demo->is_minimized = true;
        return;
    } else {
        demo->is_minimized = false;
    }

    // The FIFO present mode is guaranteed by the spec to be supported
    // and to have no tearing.  It's a great default present mode to use.
    VkPresentModeKHR swapchainPresentMode = VK_PRESENT_MODE_FIFO_KHR;

    //  There are times when you may wish to use another present mode.  The
    //  following code shows how to select them, and the comments provide some
    //  reasons you may wish to use them.
    //
    // It should be noted that Vulkan 1.0 doesn't provide a method for
    // synchronizing rendering with the presentation engine's display.  There
    // is a method provided for throttling rendering with the display, but
    // there are some presentation engines for which this method will not work.
    // If an application doesn't throttle its rendering, and if it renders much
    // faster than the refresh rate of the display, this can waste power on
    // mobile devices.  That is because power is being spent rendering images
    // that may never be seen.

    // VK_PRESENT_MODE_IMMEDIATE_KHR is for applications that don't care about
    // tearing, or have some way of synchronizing their rendering with the
    // display.
    // VK_PRESENT_MODE_MAILBOX_KHR may be useful for applications that
    // generally render a new presentable image every refresh cycle, but are
    // occasionally early.  In this case, the application wants the new image
    // to be displayed instead of the previously-queued-for-presentation image
    // that has not yet been displayed.
    // VK_PRESENT_MODE_FIFO_RELAXED_KHR is for applications that generally
    // render a new presentable image every refresh cycle, but are occasionally
    // late.  In this case (perhaps because of stuttering/latency concerns),
    // the application wants the late image to be immediately displayed, even
    // though that may mean some tearing.

    if (demo->presentMode != swapchainPresentMode) {
        for (size_t i = 0; i < presentModeCount; ++i) {
            if (presentModes[i] == demo->presentMode) {
                swapchainPresentMode = demo->presentMode;
                break;
            }
        }
    }
    if (swapchainPresentMode != demo->presentMode) {
        ERR_EXIT("Present mode specified is not supported\n", "Present mode unsupported");
    }

    // Determine the number of VkImages to use in the swap chain.
    // Application desires to acquire 3 images at a time for triple
    // buffering
    uint32_t desiredNumOfSwapchainImages = 3;
    if (desiredNumOfSwapchainImages < surfCapabilities.minImageCount) {
        desiredNumOfSwapchainImages = surfCapabilities.minImageCount;
    }
    // If maxImageCount is 0, we can ask for as many images as we want;
    // otherwise we're limited to maxImageCount
    if ((surfCapabilities.maxImageCount > 0) &&
        (desiredNumOfSwapchainImages > surfCapabilities.maxImageCount)) {
        // Application must settle for fewer images than desired:
        desiredNumOfSwapchainImages = surfCapabilities.maxImageCount;
    }

    VkSurfaceTransformFlagsKHR preTransform;
    if (surfCapabilities.supportedTransforms & VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR) {
        preTransform = VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR;
    } else {
        preTransform = surfCapabilities.currentTransform;
    }

    // Find a supported composite alpha mode - one of these is guaranteed to be set
    VkCompositeAlphaFlagBitsKHR compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
    VkCompositeAlphaFlagBitsKHR compositeAlphaFlags[4] = {
        VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR,
        VK_COMPOSITE_ALPHA_PRE_MULTIPLIED_BIT_KHR,
        VK_COMPOSITE_ALPHA_POST_MULTIPLIED_BIT_KHR,
        VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR,
    };
    for (uint32_t i = 0; i < ARRAY_SIZE(compositeAlphaFlags); i++) {
        if (surfCapabilities.supportedCompositeAlpha & compositeAlphaFlags[i]) {
            compositeAlpha = compositeAlphaFlags[i];
            break;
        }
    }

    VkSwapchainCreateInfoKHR swapchain_ci = {
        .sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR,
        .pNext = NULL,
        .surface = demo->surface,
        .minImageCount = desiredNumOfSwapchainImages,
        .imageFormat = demo->format,
        .imageColorSpace = demo->color_space,
        .imageExtent =
            {
                .width = swapchainExtent.width,
                .height = swapchainExtent.height,
            },
        .imageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT,
        .preTransform = preTransform,
        .compositeAlpha = compositeAlpha,
        .imageArrayLayers = 1,
        .imageSharingMode = VK_SHARING_MODE_EXCLUSIVE,
        .queueFamilyIndexCount = 0,
        .pQueueFamilyIndices = NULL,
        .presentMode = swapchainPresentMode,
        .oldSwapchain = oldSwapchain,
        .clipped = true,
    };
    uint32_t i;
    err = vkCreateSwapchainKHR(demo->device, &swapchain_ci, NULL, &demo->swapchain);
    assert(!err);

    // If we just re-created an existing swapchain, we should destroy the old
    // swapchain at this point.
    // Note: destroying the swapchain also cleans up all its associated
    // presentable images once the platform is done with them.
    if (oldSwapchain != VK_NULL_HANDLE) {
        vkDestroySwapchainKHR(demo->device, oldSwapchain, NULL);
    }

    err = vkGetSwapchainImagesKHR(demo->device, demo->swapchain, &demo->swapchainImageCount, NULL);
    assert(!err);

    VkImage* swapchainImages = (VkImage*)malloc(demo->swapchainImageCount * sizeof(VkImage));
    assert(swapchainImages);
    err = vkGetSwapchainImagesKHR(demo->device, demo->swapchain, &demo->swapchainImageCount, swapchainImages);
    assert(!err);

    demo->swapchain_image_resources =
        (SwapchainImageResources*)malloc(sizeof(SwapchainImageResources) * demo->swapchainImageCount);
    assert(demo->swapchain_image_resources);

    for (i = 0; i < demo->swapchainImageCount; i++) {
        VkImageViewCreateInfo color_image_view = {
            .sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO,
            .pNext = NULL,
            .format = demo->format,
            .components =
                {
                    .r = VK_COMPONENT_SWIZZLE_R,
                    .g = VK_COMPONENT_SWIZZLE_G,
                    .b = VK_COMPONENT_SWIZZLE_B,
                    .a = VK_COMPONENT_SWIZZLE_A,
                },
            .subresourceRange = { .aspectMask = VK_IMAGE_ASPECT_COLOR_BIT,
                                  .baseMipLevel = 0,
                                  .levelCount = 1,
                                  .baseArrayLayer = 0,
                                  .layerCount = 1 },
            .viewType = VK_IMAGE_VIEW_TYPE_2D,
            .flags = 0,
        };

        demo->swapchain_image_resources[i].image = swapchainImages[i];

        color_image_view.image = demo->swapchain_image_resources[i].image;

        err = vkCreateImageView(demo->device, &color_image_view, NULL,
                                &demo->swapchain_image_resources[i].view);
        assert(!err);
    }

    if (NULL != swapchainImages) {
        free(swapchainImages);
    }

    if (NULL != presentModes) {
        free(presentModes);
    }
}

static void
demo_prepare_depth(struct demo* demo)
{
    const VkFormat depth_format = VK_FORMAT_D16_UNORM;
    const VkImageCreateInfo image = {
        .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
        .pNext = NULL,
        .imageType = VK_IMAGE_TYPE_2D,
        .format = depth_format,
        .extent = { demo->width, demo->height, 1 },
        .mipLevels = 1,
        .arrayLayers = 1,
        .samples = VK_SAMPLE_COUNT_1_BIT,
        .tiling = VK_IMAGE_TILING_OPTIMAL,
        .usage = VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT,
        .flags = 0,
    };

    VkImageViewCreateInfo view = {
        .sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO,
        .pNext = NULL,
        .image = VK_NULL_HANDLE,
        .format = depth_format,
        .subresourceRange = { .aspectMask = VK_IMAGE_ASPECT_DEPTH_BIT,
                              .baseMipLevel = 0,
                              .levelCount = 1,
                              .baseArrayLayer = 0,
                              .layerCount = 1 },
        .flags = 0,
        .viewType = VK_IMAGE_VIEW_TYPE_2D,
    };

    VkMemoryRequirements mem_reqs;
    VkResult U_ASSERT_ONLY err;
    bool U_ASSERT_ONLY pass;

    demo->depth.format = depth_format;

    /* create image */
    err = vkCreateImage(demo->device, &image, NULL, &demo->depth.image);
    assert(!err);

    vkGetImageMemoryRequirements(demo->device, demo->depth.image, &mem_reqs);
    assert(!err);

    demo->depth.mem_alloc.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
    demo->depth.mem_alloc.pNext = NULL;
    demo->depth.mem_alloc.allocationSize = mem_reqs.size;
    demo->depth.mem_alloc.memoryTypeIndex = 0;

    pass = memory_type_from_properties(demo, mem_reqs.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT,
                                       &demo->depth.mem_alloc.memoryTypeIndex);
    assert(pass);

    /* allocate memory */
    err = vkAllocateMemory(demo->device, &demo->depth.mem_alloc, NULL, &demo->depth.mem);
    assert(!err);

    /* bind memory */
    err = vkBindImageMemory(demo->device, demo->depth.image, demo->depth.mem, 0);
    assert(!err);

    /* create image view */
    view.image = demo->depth.image;
    err = vkCreateImageView(demo->device, &view, NULL, &demo->depth.view);
    assert(!err);
}

/* Convert ppm image data from header file into RGBA texture image */
#include "lunarg.ppm.h"
bool
loadTexture(const char* filename, uint8_t* rgba_data, VkSubresourceLayout* layout, int32_t* width,
            int32_t* height)
{
    (void)filename;
    char* cPtr;
    cPtr = (char*)lunarg_ppm;
    if ((unsigned char*)cPtr >= (lunarg_ppm + lunarg_ppm_len) || strncmp(cPtr, "P6\n", 3)) {
        return false;
    }
    while (strncmp(cPtr++, "\n", 1))
        ;
    sscanf(cPtr, "%u %u", width, height);
    if (rgba_data == NULL) {
        return true;
    }
    while (strncmp(cPtr++, "\n", 1))
        ;
    if ((unsigned char*)cPtr >= (lunarg_ppm + lunarg_ppm_len) || strncmp(cPtr, "255\n", 4)) {
        return false;
    }
    while (strncmp(cPtr++, "\n", 1))
        ;
    for (int y = 0; y < *height; y++) {
        uint8_t* rowPtr = rgba_data;
        for (int x = 0; x < *width; x++) {
            memcpy(rowPtr, cPtr, 3);
            rowPtr[3] = 255; /* Alpha of 1 */
            rowPtr += 4;
            cPtr += 3;
        }
        rgba_data += layout->rowPitch;
    }
    return true;
}

static void
demo_prepare_texture_buffer(struct demo* demo, const char* filename, struct texture_object* tex_obj)
{
    int32_t tex_width;
    int32_t tex_height;
    VkResult U_ASSERT_ONLY err;
    bool U_ASSERT_ONLY pass;

    if (!loadTexture(filename, NULL, NULL, &tex_width, &tex_height)) {
        ERR_EXIT("Failed to load textures", "Load Texture Failure");
    }

    tex_obj->tex_width = tex_width;
    tex_obj->tex_height = tex_height;

    const VkBufferCreateInfo buffer_create_info = { .sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO,
                                                    .pNext = NULL,
                                                    .flags = 0,
                                                    .size = tex_width * tex_height * 4,
                                                    .usage = VK_BUFFER_USAGE_TRANSFER_SRC_BIT,
                                                    .sharingMode = VK_SHARING_MODE_EXCLUSIVE,
                                                    .queueFamilyIndexCount = 0,
                                                    .pQueueFamilyIndices = NULL };

    err = vkCreateBuffer(demo->device, &buffer_create_info, NULL, &tex_obj->buffer);
    assert(!err);

    VkMemoryRequirements mem_reqs;
    vkGetBufferMemoryRequirements(demo->device, tex_obj->buffer, &mem_reqs);

    tex_obj->mem_alloc.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
    tex_obj->mem_alloc.pNext = NULL;
    tex_obj->mem_alloc.allocationSize = mem_reqs.size;
    tex_obj->mem_alloc.memoryTypeIndex = 0;

    VkFlags requirements = VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT;
    pass = memory_type_from_properties(demo, mem_reqs.memoryTypeBits, requirements,
                                       &tex_obj->mem_alloc.memoryTypeIndex);
    assert(pass);

    err = vkAllocateMemory(demo->device, &tex_obj->mem_alloc, NULL, &(tex_obj->mem));
    assert(!err);

    /* bind memory */
    err = vkBindBufferMemory(demo->device, tex_obj->buffer, tex_obj->mem, 0);
    assert(!err);

    VkSubresourceLayout layout;
    memset(&layout, 0, sizeof(layout));
    layout.rowPitch = tex_width * 4;

    void* data;
    err = vkMapMemory(demo->device, tex_obj->mem, 0, tex_obj->mem_alloc.allocationSize, 0, &data);
    assert(!err);

    if (!loadTexture(filename, data, &layout, &tex_width, &tex_height)) {
        fprintf(stderr, "Error loading texture: %s\n", filename);
    }

    vkUnmapMemory(demo->device, tex_obj->mem);
}

static void
demo_prepare_texture_image(struct demo* demo, const char* filename, struct texture_object* tex_obj,
                           VkImageTiling tiling, VkImageUsageFlags usage, VkFlags required_props)
{
    const VkFormat tex_format = VK_FORMAT_R8G8B8A8_UNORM;
    int32_t tex_width;
    int32_t tex_height;
    VkResult U_ASSERT_ONLY err;
    bool U_ASSERT_ONLY pass;

    if (!loadTexture(filename, NULL, NULL, &tex_width, &tex_height)) {
        ERR_EXIT("Failed to load textures", "Load Texture Failure");
    }

    tex_obj->tex_width = tex_width;
    tex_obj->tex_height = tex_height;

    const VkImageCreateInfo image_create_info = {
        .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
        .pNext = NULL,
        .imageType = VK_IMAGE_TYPE_2D,
        .format = tex_format,
        .extent = { tex_width, tex_height, 1 },
        .mipLevels = 1,
        .arrayLayers = 1,
        .samples = VK_SAMPLE_COUNT_1_BIT,
        .tiling = tiling,
        .usage = usage,
        .flags = 0,
        .initialLayout = VK_IMAGE_LAYOUT_PREINITIALIZED,
    };

    VkMemoryRequirements mem_reqs;

    err = vkCreateImage(demo->device, &image_create_info, NULL, &tex_obj->image);
    assert(!err);

    vkGetImageMemoryRequirements(demo->device, tex_obj->image, &mem_reqs);

    tex_obj->mem_alloc.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
    tex_obj->mem_alloc.pNext = NULL;
    tex_obj->mem_alloc.allocationSize = mem_reqs.size;
    tex_obj->mem_alloc.memoryTypeIndex = 0;

    pass = memory_type_from_properties(demo, mem_reqs.memoryTypeBits, required_props,
                                       &tex_obj->mem_alloc.memoryTypeIndex);
    assert(pass);

    /* allocate memory */
    err = vkAllocateMemory(demo->device, &tex_obj->mem_alloc, NULL, &(tex_obj->mem));
    assert(!err);

    /* bind memory */
    err = vkBindImageMemory(demo->device, tex_obj->image, tex_obj->mem, 0);
    assert(!err);

    if (required_props & VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT) {
        const VkImageSubresource subres = {
            .aspectMask = VK_IMAGE_ASPECT_COLOR_BIT,
            .mipLevel = 0,
            .arrayLayer = 0,
        };
        VkSubresourceLayout layout;
        void* data;

        vkGetImageSubresourceLayout(demo->device, tex_obj->image, &subres, &layout);

        err = vkMapMemory(demo->device, tex_obj->mem, 0, tex_obj->mem_alloc.allocationSize, 0, &data);
        assert(!err);

        if (!loadTexture(filename, data, &layout, &tex_width, &tex_height)) {
            fprintf(stderr, "Error loading texture: %s\n", filename);
        }

        vkUnmapMemory(demo->device, tex_obj->mem);
    }

    tex_obj->imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
}

static void
demo_destroy_texture(struct demo* demo, struct texture_object* tex_objs)
{
    /* clean up staging resources */
    vkFreeMemory(demo->device, tex_objs->mem, NULL);
    if (tex_objs->image)
        vkDestroyImage(demo->device, tex_objs->image, NULL);
    if (tex_objs->buffer)
        vkDestroyBuffer(demo->device, tex_objs->buffer, NULL);
}

static void
demo_prepare_textures(struct demo* demo)
{
    const VkFormat tex_format = VK_FORMAT_R8G8B8A8_UNORM;
    VkFormatProperties props;
    uint32_t i;

    vkGetPhysicalDeviceFormatProperties(demo->gpu, tex_format, &props);

    for (i = 0; i < DEMO_TEXTURE_COUNT; i++) {
        VkResult U_ASSERT_ONLY err;

        if ((props.linearTilingFeatures & VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT) && !demo->use_staging_buffer) {
            /* Device can texture using linear textures */
            demo_prepare_texture_image(
                demo, tex_files[i], &demo->textures[i], VK_IMAGE_TILING_LINEAR, VK_IMAGE_USAGE_SAMPLED_BIT,
                VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
            // Nothing in the pipeline needs to be complete to start, and don't allow fragment
            // shader to run until layout transition completes
            demo_set_image_layout(demo, demo->textures[i].image, VK_IMAGE_ASPECT_COLOR_BIT,
                                  VK_IMAGE_LAYOUT_PREINITIALIZED, demo->textures[i].imageLayout, 0,
                                  VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT);
            demo->staging_texture.image = 0;
        } else if (props.optimalTilingFeatures & VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT) {
            /* Must use staging buffer to copy linear texture to optimized */

            memset(&demo->staging_texture, 0, sizeof(demo->staging_texture));
            demo_prepare_texture_buffer(demo, tex_files[i], &demo->staging_texture);

            demo_prepare_texture_image(demo, tex_files[i], &demo->textures[i], VK_IMAGE_TILING_OPTIMAL,
                                       (VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_SAMPLED_BIT),
                                       VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);

            demo_set_image_layout(demo, demo->textures[i].image, VK_IMAGE_ASPECT_COLOR_BIT,
                                  VK_IMAGE_LAYOUT_PREINITIALIZED, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 0,
                                  VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_TRANSFER_BIT);

            VkBufferImageCopy copy_region = {
                .bufferOffset = 0,
                .bufferRowLength = demo->staging_texture.tex_width,
                .bufferImageHeight = demo->staging_texture.tex_height,
                .imageSubresource = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 0, 1 },
                .imageOffset = { 0, 0, 0 },
                .imageExtent = { demo->staging_texture.tex_width, demo->staging_texture.tex_height, 1 },
            };

            vkCmdCopyBufferToImage(demo->cmd, demo->staging_texture.buffer, demo->textures[i].image,
                                   VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, &copy_region);

            demo_set_image_layout(demo, demo->textures[i].image, VK_IMAGE_ASPECT_COLOR_BIT,
                                  VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, demo->textures[i].imageLayout,
                                  VK_ACCESS_TRANSFER_WRITE_BIT, VK_PIPELINE_STAGE_TRANSFER_BIT,
                                  VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT);

        } else {
            /* Can't support VK_FORMAT_R8G8B8A8_UNORM !? */
            assert(!"No support for R8G8B8A8_UNORM as texture image format");
        }

        const VkSamplerCreateInfo sampler = {
            .sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO,
            .pNext = NULL,
            .magFilter = VK_FILTER_NEAREST,
            .minFilter = VK_FILTER_NEAREST,
            .mipmapMode = VK_SAMPLER_MIPMAP_MODE_NEAREST,
            .addressModeU = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE,
            .addressModeV = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE,
            .addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE,
            .mipLodBias = 0.0f,
            .anisotropyEnable = VK_FALSE,
            .maxAnisotropy = 1,
            .compareOp = VK_COMPARE_OP_NEVER,
            .minLod = 0.0f,
            .maxLod = 0.0f,
            .borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE,
            .unnormalizedCoordinates = VK_FALSE,
        };

        VkImageViewCreateInfo view = {
            .sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO,
            .pNext = NULL,
            .image = VK_NULL_HANDLE,
            .viewType = VK_IMAGE_VIEW_TYPE_2D,
            .format = tex_format,
            .components =
                {
                    VK_COMPONENT_SWIZZLE_R,
                    VK_COMPONENT_SWIZZLE_G,
                    VK_COMPONENT_SWIZZLE_B,
                    VK_COMPONENT_SWIZZLE_A,
                },
            .subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 },
            .flags = 0,
        };

        /* create sampler */
        err = vkCreateSampler(demo->device, &sampler, NULL, &demo->textures[i].sampler);
        assert(!err);

        /* create image view */
        view.image = demo->textures[i].image;
        err = vkCreateImageView(demo->device, &view, NULL, &demo->textures[i].view);
        assert(!err);
    }
}

void
demo_prepare_cube_data_buffers(struct demo* demo)
{
    VkBufferCreateInfo buf_info;
    VkMemoryRequirements mem_reqs;
    VkMemoryAllocateInfo mem_alloc;
    uint8_t* pData;
    mat4x4 MVP, VP;
    VkResult U_ASSERT_ONLY err;
    bool U_ASSERT_ONLY pass;
    struct vktexcube_vs_uniform data;

    mat4x4_mul(VP, demo->projection_matrix, demo->view_matrix);
    mat4x4_mul(MVP, VP, demo->model_matrix);
    memcpy(data.mvp, MVP, sizeof(MVP));
    //    dumpMatrix("MVP", MVP);

    for (unsigned int i = 0; i < 12 * 3; i++) {
        data.position[i][0] = g_vertex_buffer_data[i * 3];
        data.position[i][1] = g_vertex_buffer_data[i * 3 + 1];
        data.position[i][2] = g_vertex_buffer_data[i * 3 + 2];
        data.position[i][3] = 1.0f;
        data.attr[i][0] = g_uv_buffer_data[2 * i];
        data.attr[i][1] = g_uv_buffer_data[2 * i + 1];
        data.attr[i][2] = 0;
        data.attr[i][3] = 0;
    }

    memset(&buf_info, 0, sizeof(buf_info));
    buf_info.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
    buf_info.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT;
    buf_info.size = sizeof(data);

    for (unsigned int i = 0; i < demo->swapchainImageCount; i++) {
        err =
            vkCreateBuffer(demo->device, &buf_info, NULL, &demo->swapchain_image_resources[i].uniform_buffer);
        assert(!err);

        vkGetBufferMemoryRequirements(demo->device, demo->swapchain_image_resources[i].uniform_buffer,
                                      &mem_reqs);

        mem_alloc.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
        mem_alloc.pNext = NULL;
        mem_alloc.allocationSize = mem_reqs.size;
        mem_alloc.memoryTypeIndex = 0;

        pass = memory_type_from_properties(demo, mem_reqs.memoryTypeBits,
                                           VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT |
                                               VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
                                           &mem_alloc.memoryTypeIndex);
        assert(pass);

        err = vkAllocateMemory(demo->device, &mem_alloc, NULL,
                               &demo->swapchain_image_resources[i].uniform_memory);
        assert(!err);

        err = vkMapMemory(demo->device, demo->swapchain_image_resources[i].uniform_memory, 0, VK_WHOLE_SIZE,
                          0, (void**)&pData);
        assert(!err);

        memcpy(pData, &data, sizeof data);

        vkUnmapMemory(demo->device, demo->swapchain_image_resources[i].uniform_memory);

        err = vkBindBufferMemory(demo->device, demo->swapchain_image_resources[i].uniform_buffer,
                                 demo->swapchain_image_resources[i].uniform_memory, 0);
        assert(!err);
    }
}

static void
demo_prepare_descriptor_layout(struct demo* demo)
{
    const VkDescriptorSetLayoutBinding layout_bindings[2] = {
        [0] =
            {
                .binding = 0,
                .descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER,
                .descriptorCount = 1,
                .stageFlags = VK_SHADER_STAGE_VERTEX_BIT,
                .pImmutableSamplers = NULL,
            },
        [1] =
            {
                .binding = 1,
                .descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER,
                .descriptorCount = DEMO_TEXTURE_COUNT,
                .stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT,
                .pImmutableSamplers = NULL,
            },
    };
    const VkDescriptorSetLayoutCreateInfo descriptor_layout = {
        .sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO,
        .pNext = NULL,
        .bindingCount = 2,
        .pBindings = layout_bindings,
    };
    VkResult U_ASSERT_ONLY err;

    err = vkCreateDescriptorSetLayout(demo->device, &descriptor_layout, NULL, &demo->desc_layout);
    assert(!err);

    const VkPipelineLayoutCreateInfo pPipelineLayoutCreateInfo = {
        .sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO,
        .pNext = NULL,
        .setLayoutCount = 1,
        .pSetLayouts = &demo->desc_layout,
    };

    err = vkCreatePipelineLayout(demo->device, &pPipelineLayoutCreateInfo, NULL, &demo->pipeline_layout);
    assert(!err);
}

static void
demo_prepare_render_pass(struct demo* demo)
{
    // The initial layout for the color and depth attachments will be LAYOUT_UNDEFINED
    // because at the start of the renderpass, we don't care about their contents.
    // At the start of the subpass, the color attachment's layout will be transitioned
    // to LAYOUT_COLOR_ATTACHMENT_OPTIMAL and the depth stencil attachment's layout
    // will be transitioned to LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL.  At the end of
    // the renderpass, the color attachment's layout will be transitioned to
    // LAYOUT_PRESENT_SRC_KHR to be ready to present.  This is all done as part of
    // the renderpass, no barriers are necessary.
    const VkAttachmentDescription attachments[2] = {
        [0] =
            {
                .format = demo->format,
                .flags = 0,
                .samples = VK_SAMPLE_COUNT_1_BIT,
                .loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR,
                .storeOp = VK_ATTACHMENT_STORE_OP_STORE,
                .stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE,
                .stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE,
                .initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
                .finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
            },
        [1] =
            {
                .format = demo->depth.format,
                .flags = 0,
                .samples = VK_SAMPLE_COUNT_1_BIT,
                .loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR,
                .storeOp = VK_ATTACHMENT_STORE_OP_DONT_CARE,
                .stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE,
                .stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE,
                .initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
                .finalLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL,
            },
    };
    const VkAttachmentReference color_reference = {
        .attachment = 0,
        .layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL,
    };
    const VkAttachmentReference depth_reference = {
        .attachment = 1,
        .layout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL,
    };
    const VkSubpassDescription subpass = {
        .pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS,
        .flags = 0,
        .inputAttachmentCount = 0,
        .pInputAttachments = NULL,
        .colorAttachmentCount = 1,
        .pColorAttachments = &color_reference,
        .pResolveAttachments = NULL,
        .pDepthStencilAttachment = &depth_reference,
        .preserveAttachmentCount = 0,
        .pPreserveAttachments = NULL,
    };
    const VkRenderPassCreateInfo rp_info = {
        .sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO,
        .pNext = NULL,
        .flags = 0,
        .attachmentCount = 2,
        .pAttachments = attachments,
        .subpassCount = 1,
        .pSubpasses = &subpass,
        .dependencyCount = 0,
        .pDependencies = NULL,
    };
    VkResult U_ASSERT_ONLY err;

    err = vkCreateRenderPass(demo->device, &rp_info, NULL, &demo->render_pass);
    assert(!err);
}

static VkShaderModule
demo_prepare_shader_module(struct demo* demo, const uint32_t* code, size_t size)
{
    VkShaderModule module;
    VkShaderModuleCreateInfo moduleCreateInfo;
    VkResult U_ASSERT_ONLY err;

    moduleCreateInfo.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
    moduleCreateInfo.pNext = NULL;
    moduleCreateInfo.flags = 0;
    moduleCreateInfo.codeSize = size;
    moduleCreateInfo.pCode = code;

    err = vkCreateShaderModule(demo->device, &moduleCreateInfo, NULL, &module);
    assert(!err);

    return module;
}

static void
demo_prepare_vs(struct demo* demo)
{
    const uint32_t vs_code[] = {
#include "cube.vert.inc"
    };
    demo->vert_shader_module = demo_prepare_shader_module(demo, vs_code, sizeof(vs_code));
}

static void
demo_prepare_fs(struct demo* demo)
{
    const uint32_t fs_code[] = {
#include "cube.frag.inc"
    };
    demo->frag_shader_module = demo_prepare_shader_module(demo, fs_code, sizeof(fs_code));
}

static void
demo_prepare_pipeline(struct demo* demo)
{
    VkGraphicsPipelineCreateInfo pipeline;
    VkPipelineCacheCreateInfo pipelineCache;
    VkPipelineVertexInputStateCreateInfo vi;
    VkPipelineInputAssemblyStateCreateInfo ia;
    VkPipelineRasterizationStateCreateInfo rs;
    VkPipelineColorBlendStateCreateInfo cb;
    VkPipelineDepthStencilStateCreateInfo ds;
    VkPipelineViewportStateCreateInfo vp;
    VkPipelineMultisampleStateCreateInfo ms;
    VkDynamicState dynamicStateEnables[VK_DYNAMIC_STATE_RANGE_SIZE];
    VkPipelineDynamicStateCreateInfo dynamicState;
    VkResult U_ASSERT_ONLY err;

    memset(dynamicStateEnables, 0, sizeof dynamicStateEnables);
    memset(&dynamicState, 0, sizeof dynamicState);
    dynamicState.sType = VK_STRUCTURE_TYPE_PIPELINE_DYNAMIC_STATE_CREATE_INFO;
    dynamicState.pDynamicStates = dynamicStateEnables;

    memset(&pipeline, 0, sizeof(pipeline));
    pipeline.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
    pipeline.layout = demo->pipeline_layout;

    memset(&vi, 0, sizeof(vi));
    vi.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;

    memset(&ia, 0, sizeof(ia));
    ia.sType = VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO;
    ia.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;

    memset(&rs, 0, sizeof(rs));
    rs.sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO;
    rs.polygonMode = VK_POLYGON_MODE_FILL;
    rs.cullMode = VK_CULL_MODE_BACK_BIT;
    rs.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE;
    rs.depthClampEnable = VK_FALSE;
    rs.rasterizerDiscardEnable = VK_FALSE;
    rs.depthBiasEnable = VK_FALSE;
    rs.lineWidth = 1.0f;

    memset(&cb, 0, sizeof(cb));
    cb.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
    VkPipelineColorBlendAttachmentState att_state[1];
    memset(att_state, 0, sizeof(att_state));
    att_state[0].colorWriteMask = 0xf;
    att_state[0].blendEnable = VK_FALSE;
    cb.attachmentCount = 1;
    cb.pAttachments = att_state;

    memset(&vp, 0, sizeof(vp));
    vp.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
    vp.viewportCount = 1;
    dynamicStateEnables[dynamicState.dynamicStateCount++] = VK_DYNAMIC_STATE_VIEWPORT;
    vp.scissorCount = 1;
    dynamicStateEnables[dynamicState.dynamicStateCount++] = VK_DYNAMIC_STATE_SCISSOR;

    memset(&ds, 0, sizeof(ds));
    ds.sType = VK_STRUCTURE_TYPE_PIPELINE_DEPTH_STENCIL_STATE_CREATE_INFO;
    ds.depthTestEnable = VK_TRUE;
    ds.depthWriteEnable = VK_TRUE;
    ds.depthCompareOp = VK_COMPARE_OP_LESS_OR_EQUAL;
    ds.depthBoundsTestEnable = VK_FALSE;
    ds.back.failOp = VK_STENCIL_OP_KEEP;
    ds.back.passOp = VK_STENCIL_OP_KEEP;
    ds.back.compareOp = VK_COMPARE_OP_ALWAYS;
    ds.stencilTestEnable = VK_FALSE;
    ds.front = ds.back;

    memset(&ms, 0, sizeof(ms));
    ms.sType = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO;
    ms.pSampleMask = NULL;
    ms.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;

    demo_prepare_vs(demo);
    demo_prepare_fs(demo);

    // Two stages: vs and fs
    VkPipelineShaderStageCreateInfo shaderStages[2];
    memset(&shaderStages, 0, 2 * sizeof(VkPipelineShaderStageCreateInfo));

    shaderStages[0].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
    shaderStages[0].stage = VK_SHADER_STAGE_VERTEX_BIT;
    shaderStages[0].module = demo->vert_shader_module;
    shaderStages[0].pName = "main";

    shaderStages[1].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
    shaderStages[1].stage = VK_SHADER_STAGE_FRAGMENT_BIT;
    shaderStages[1].module = demo->frag_shader_module;
    shaderStages[1].pName = "main";

    memset(&pipelineCache, 0, sizeof(pipelineCache));
    pipelineCache.sType = VK_STRUCTURE_TYPE_PIPELINE_CACHE_CREATE_INFO;

    err = vkCreatePipelineCache(demo->device, &pipelineCache, NULL, &demo->pipelineCache);
    assert(!err);

    pipeline.pVertexInputState = &vi;
    pipeline.pInputAssemblyState = &ia;
    pipeline.pRasterizationState = &rs;
    pipeline.pColorBlendState = &cb;
    pipeline.pMultisampleState = &ms;
    pipeline.pViewportState = &vp;
    pipeline.pDepthStencilState = &ds;
    pipeline.stageCount = ARRAY_SIZE(shaderStages);
    pipeline.pStages = shaderStages;
    pipeline.renderPass = demo->render_pass;
    pipeline.pDynamicState = &dynamicState;

    pipeline.renderPass = demo->render_pass;

    err = vkCreateGraphicsPipelines(demo->device, demo->pipelineCache, 1, &pipeline, NULL, &demo->pipeline);
    assert(!err);

    vkDestroyShaderModule(demo->device, demo->frag_shader_module, NULL);
    vkDestroyShaderModule(demo->device, demo->vert_shader_module, NULL);
}

static void
demo_prepare_descriptor_pool(struct demo* demo)
{
    const VkDescriptorPoolSize type_counts[2] = {
        [0] =
            {
                .type = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER,
                .descriptorCount = demo->swapchainImageCount,
            },
        [1] =
            {
                .type = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER,
                .descriptorCount = demo->swapchainImageCount * DEMO_TEXTURE_COUNT,
            },
    };
    const VkDescriptorPoolCreateInfo descriptor_pool = {
        .sType = VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO,
        .pNext = NULL,
        .maxSets = demo->swapchainImageCount,
        .poolSizeCount = 2,
        .pPoolSizes = type_counts,
    };
    VkResult U_ASSERT_ONLY err;

    err = vkCreateDescriptorPool(demo->device, &descriptor_pool, NULL, &demo->desc_pool);
    assert(!err);
}

static void
demo_prepare_descriptor_set(struct demo* demo)
{
    VkDescriptorImageInfo tex_descs[DEMO_TEXTURE_COUNT];
    VkWriteDescriptorSet writes[2];
    VkResult U_ASSERT_ONLY err;

    VkDescriptorSetAllocateInfo alloc_info = { .sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO,
                                               .pNext = NULL,
                                               .descriptorPool = demo->desc_pool,
                                               .descriptorSetCount = 1,
                                               .pSetLayouts = &demo->desc_layout };

    VkDescriptorBufferInfo buffer_info;
    buffer_info.offset = 0;
    buffer_info.range = sizeof(struct vktexcube_vs_uniform);

    memset(&tex_descs, 0, sizeof(tex_descs));
    for (unsigned int i = 0; i < DEMO_TEXTURE_COUNT; i++) {
        tex_descs[i].sampler = demo->textures[i].sampler;
        tex_descs[i].imageView = demo->textures[i].view;
        tex_descs[i].imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
    }

    memset(&writes, 0, sizeof(writes));

    writes[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
    writes[0].descriptorCount = 1;
    writes[0].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
    writes[0].pBufferInfo = &buffer_info;

    writes[1].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
    writes[1].dstBinding = 1;
    writes[1].descriptorCount = DEMO_TEXTURE_COUNT;
    writes[1].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
    writes[1].pImageInfo = tex_descs;

    for (unsigned int i = 0; i < demo->swapchainImageCount; i++) {
        err = vkAllocateDescriptorSets(demo->device, &alloc_info,
                                       &demo->swapchain_image_resources[i].descriptor_set);
        assert(!err);
        buffer_info.buffer = demo->swapchain_image_resources[i].uniform_buffer;
        writes[0].dstSet = demo->swapchain_image_resources[i].descriptor_set;
        writes[1].dstSet = demo->swapchain_image_resources[i].descriptor_set;
        vkUpdateDescriptorSets(demo->device, 2, writes, 0, NULL);
    }
}

static void
demo_prepare_framebuffers(struct demo* demo)
{
    VkImageView attachments[2];
    attachments[1] = demo->depth.view;

    const VkFramebufferCreateInfo fb_info = {
        .sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO,
        .pNext = NULL,
        .renderPass = demo->render_pass,
        .attachmentCount = 2,
        .pAttachments = attachments,
        .width = demo->width,
        .height = demo->height,
        .layers = 1,
    };
    VkResult U_ASSERT_ONLY err;
    uint32_t i;

    for (i = 0; i < demo->swapchainImageCount; i++) {
        attachments[0] = demo->swapchain_image_resources[i].view;
        err = vkCreateFramebuffer(demo->device, &fb_info, NULL,
                                  &demo->swapchain_image_resources[i].framebuffer);
        assert(!err);
    }
}

static void
demo_prepare(struct demo* demo)
{
    VkResult U_ASSERT_ONLY err;
    if (demo->cmd_pool == VK_NULL_HANDLE) {
        const VkCommandPoolCreateInfo cmd_pool_info = {
            .sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO,
            .pNext = NULL,
            .queueFamilyIndex = demo->graphics_queue_family_index,
            .flags = 0,
        };
        err = vkCreateCommandPool(demo->device, &cmd_pool_info, NULL, &demo->cmd_pool);
        assert(!err);
    }

    const VkCommandBufferAllocateInfo cmd = {
        .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
        .pNext = NULL,
        .commandPool = demo->cmd_pool,
        .level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
        .commandBufferCount = 1,
    };
    err = vkAllocateCommandBuffers(demo->device, &cmd, &demo->cmd);
    assert(!err);
    VkCommandBufferBeginInfo cmd_buf_info = {
        .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
        .pNext = NULL,
        .flags = 0,
        .pInheritanceInfo = NULL,
    };
    err = vkBeginCommandBuffer(demo->cmd, &cmd_buf_info);
    assert(!err);

    demo_prepare_buffers(demo);

    if (demo->is_minimized) {
        demo->prepared = false;
        return;
    }

    demo_prepare_depth(demo);
    demo_prepare_textures(demo);
    demo_prepare_cube_data_buffers(demo);

    demo_prepare_descriptor_layout(demo);
    demo_prepare_render_pass(demo);
    demo_prepare_pipeline(demo);

    for (uint32_t i = 0; i < demo->swapchainImageCount; i++) {
        err = vkAllocateCommandBuffers(demo->device, &cmd, &demo->swapchain_image_resources[i].cmd);
        assert(!err);
    }

    if (demo->separate_present_queue) {
        const VkCommandPoolCreateInfo present_cmd_pool_info = {
            .sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO,
            .pNext = NULL,
            .queueFamilyIndex = demo->present_queue_family_index,
            .flags = 0,
        };
        err = vkCreateCommandPool(demo->device, &present_cmd_pool_info, NULL, &demo->present_cmd_pool);
        assert(!err);
        const VkCommandBufferAllocateInfo present_cmd_info = {
            .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
            .pNext = NULL,
            .commandPool = demo->present_cmd_pool,
            .level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
            .commandBufferCount = 1,
        };
        for (uint32_t i = 0; i < demo->swapchainImageCount; i++) {
            err = vkAllocateCommandBuffers(demo->device, &present_cmd_info,
                                           &demo->swapchain_image_resources[i].graphics_to_present_cmd);
            assert(!err);
            demo_build_image_ownership_cmd(demo, i);
        }
    }

    demo_prepare_descriptor_pool(demo);
    demo_prepare_descriptor_set(demo);

    demo_prepare_framebuffers(demo);

    for (uint32_t i = 0; i < demo->swapchainImageCount; i++) {
        demo->current_buffer = i;
        demo_draw_build_cmd(demo, demo->swapchain_image_resources[i].cmd);
    }

    /*
     * Prepare functions above may generate pipeline commands
     * that need to be flushed before beginning the render loop.
     */
    demo_flush_init_cmd(demo);
    if (demo->staging_texture.buffer) {
        demo_destroy_texture(demo, &demo->staging_texture);
    }

    demo->current_buffer = 0;
    demo->prepared = true;
}

static void
demo_cleanup(struct demo* demo)
{
    uint32_t i;

    demo->prepared = false;
    vkDeviceWaitIdle(demo->device);

    // Wait for fences from present operations
    for (i = 0; i < FRAME_LAG; i++) {
        vkWaitForFences(demo->device, 1, &demo->fences[i], VK_TRUE, UINT64_MAX);
        vkDestroyFence(demo->device, demo->fences[i], NULL);
        vkDestroySemaphore(demo->device, demo->image_acquired_semaphores[i], NULL);
        vkDestroySemaphore(demo->device, demo->draw_complete_semaphores[i], NULL);
        if (demo->separate_present_queue) {
            vkDestroySemaphore(demo->device, demo->image_ownership_semaphores[i], NULL);
        }
    }

    // If the window is currently minimized, demo_resize has already done some cleanup for us.
    if (!demo->is_minimized) {
        for (i = 0; i < demo->swapchainImageCount; i++) {
            vkDestroyFramebuffer(demo->device, demo->swapchain_image_resources[i].framebuffer, NULL);
        }
        vkDestroyDescriptorPool(demo->device, demo->desc_pool, NULL);

        vkDestroyPipeline(demo->device, demo->pipeline, NULL);
        vkDestroyPipelineCache(demo->device, demo->pipelineCache, NULL);
        vkDestroyRenderPass(demo->device, demo->render_pass, NULL);
        vkDestroyPipelineLayout(demo->device, demo->pipeline_layout, NULL);
        vkDestroyDescriptorSetLayout(demo->device, demo->desc_layout, NULL);

        for (i = 0; i < DEMO_TEXTURE_COUNT; i++) {
            vkDestroyImageView(demo->device, demo->textures[i].view, NULL);
            vkDestroyImage(demo->device, demo->textures[i].image, NULL);
            vkFreeMemory(demo->device, demo->textures[i].mem, NULL);
            vkDestroySampler(demo->device, demo->textures[i].sampler, NULL);
        }
        vkDestroySwapchainKHR(demo->device, demo->swapchain, NULL);

        vkDestroyImageView(demo->device, demo->depth.view, NULL);
        vkDestroyImage(demo->device, demo->depth.image, NULL);
        vkFreeMemory(demo->device, demo->depth.mem, NULL);

        for (i = 0; i < demo->swapchainImageCount; i++) {
            vkDestroyImageView(demo->device, demo->swapchain_image_resources[i].view, NULL);
            vkFreeCommandBuffers(demo->device, demo->cmd_pool, 1, &demo->swapchain_image_resources[i].cmd);
            vkDestroyBuffer(demo->device, demo->swapchain_image_resources[i].uniform_buffer, NULL);
            vkFreeMemory(demo->device, demo->swapchain_image_resources[i].uniform_memory, NULL);
        }
        free(demo->swapchain_image_resources);
        free(demo->queue_props);
        vkDestroyCommandPool(demo->device, demo->cmd_pool, NULL);

        if (demo->separate_present_queue) {
            vkDestroyCommandPool(demo->device, demo->present_cmd_pool, NULL);
        }
    }
    vkDeviceWaitIdle(demo->device);
    vkDestroyDevice(demo->device, NULL);
    if (demo->validate) {
        demo->DestroyDebugUtilsMessengerEXT(demo->inst, demo->dbg_messenger, NULL);
    }

    vkDestroySurfaceKHR(demo->inst, demo->surface, NULL);
    vkDestroyInstance(demo->inst, NULL);
}

static void
demo_resize(struct demo* demo)
{
    uint32_t i;

    // Don't react to resize until after first initialization.
    if (!demo->prepared) {
        if (demo->is_minimized) {
            demo_prepare(demo);
        }
        return;
    }
    // In order to properly resize the window, we must re-create the swapchain
    // AND redo the command buffers, etc.
    //
    // First, perform part of the demo_cleanup() function:
    demo->prepared = false;
    vkDeviceWaitIdle(demo->device);

    for (i = 0; i < demo->swapchainImageCount; i++) {
        vkDestroyFramebuffer(demo->device, demo->swapchain_image_resources[i].framebuffer, NULL);
    }
    vkDestroyDescriptorPool(demo->device, demo->desc_pool, NULL);

    vkDestroyPipeline(demo->device, demo->pipeline, NULL);
    vkDestroyPipelineCache(demo->device, demo->pipelineCache, NULL);
    vkDestroyRenderPass(demo->device, demo->render_pass, NULL);
    vkDestroyPipelineLayout(demo->device, demo->pipeline_layout, NULL);
    vkDestroyDescriptorSetLayout(demo->device, demo->desc_layout, NULL);

    for (i = 0; i < DEMO_TEXTURE_COUNT; i++) {
        vkDestroyImageView(demo->device, demo->textures[i].view, NULL);
        vkDestroyImage(demo->device, demo->textures[i].image, NULL);
        vkFreeMemory(demo->device, demo->textures[i].mem, NULL);
        vkDestroySampler(demo->device, demo->textures[i].sampler, NULL);
    }

    vkDestroyImageView(demo->device, demo->depth.view, NULL);
    vkDestroyImage(demo->device, demo->depth.image, NULL);
    vkFreeMemory(demo->device, demo->depth.mem, NULL);

    for (i = 0; i < demo->swapchainImageCount; i++) {
        vkDestroyImageView(demo->device, demo->swapchain_image_resources[i].view, NULL);
        vkFreeCommandBuffers(demo->device, demo->cmd_pool, 1, &demo->swapchain_image_resources[i].cmd);
        vkDestroyBuffer(demo->device, demo->swapchain_image_resources[i].uniform_buffer, NULL);
        vkFreeMemory(demo->device, demo->swapchain_image_resources[i].uniform_memory, NULL);
    }
    vkDestroyCommandPool(demo->device, demo->cmd_pool, NULL);
    demo->cmd_pool = VK_NULL_HANDLE;
    if (demo->separate_present_queue) {
        vkDestroyCommandPool(demo->device, demo->present_cmd_pool, NULL);
    }
    free(demo->swapchain_image_resources);

    // Second, re-perform the demo_prepare() function, which will re-create the
    // swapchain:
    demo_prepare(demo);
}

/*
 * Return 1 (true) if all layer names specified in check_names
 * can be found in given layer properties.
 */
static VkBool32
demo_check_layers(uint32_t check_count, char** check_names, uint32_t layer_count, VkLayerProperties* layers)
{
    for (uint32_t i = 0; i < check_count; i++) {
        VkBool32 found = 0;
        for (uint32_t j = 0; j < layer_count; j++) {
            if (!strcmp(check_names[i], layers[j].layerName)) {
                found = 1;
                break;
            }
        }
        if (!found) {
            fprintf(stderr, "Cannot find layer: %s\n", check_names[i]);
            return 0;
        }
    }
    return 1;
}

static void
demo_init_vk(struct demo* demo)
{
    VkResult err;
    uint32_t instance_extension_count = 0;
    uint32_t instance_layer_count = 0;
    char* instance_validation_layers[] = { "VK_LAYER_KHRONOS_validation" };
    demo->enabled_extension_count = 0;
    demo->enabled_layer_count = 0;
    demo->is_minimized = false;
    demo->cmd_pool = VK_NULL_HANDLE;

    // Look for validation layers
    VkBool32 validation_found = 0;
    if (demo->validate) {
        err = vkEnumerateInstanceLayerProperties(&instance_layer_count, NULL);
        assert(!err);

        if (instance_layer_count > 0) {
            VkLayerProperties* instance_layers = malloc(sizeof(VkLayerProperties) * instance_layer_count);
            err = vkEnumerateInstanceLayerProperties(&instance_layer_count, instance_layers);
            assert(!err);

            validation_found =
                demo_check_layers(ARRAY_SIZE(instance_validation_layers), instance_validation_layers,
                                  instance_layer_count, instance_layers);
            if (validation_found) {
                demo->enabled_layer_count = ARRAY_SIZE(instance_validation_layers);
                demo->enabled_layers[0] = "VK_LAYER_KHRONOS_validation";
            }
            free(instance_layers);
        }
    }

    /* Look for instance extensions */
    VkBool32 surfaceExtFound = 0;
    VkBool32 platformSurfaceExtFound = 0;
    memset(demo->extension_names, 0, sizeof(demo->extension_names));

    err = vkEnumerateInstanceExtensionProperties(NULL, &instance_extension_count, NULL);
    assert(!err);

    if (instance_extension_count > 0) {
        VkExtensionProperties* instance_extensions =
            malloc(sizeof(VkExtensionProperties) * instance_extension_count);
        err = vkEnumerateInstanceExtensionProperties(NULL, &instance_extension_count, instance_extensions);
        assert(!err);
        for (uint32_t i = 0; i < instance_extension_count; i++) {
            if (!strcmp(VK_KHR_SURFACE_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                surfaceExtFound = 1;
                demo->extension_names[demo->enabled_extension_count++] = VK_KHR_SURFACE_EXTENSION_NAME;
            }
            if (!strcmp(VK_KHR_WIN32_SURFACE_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                platformSurfaceExtFound = 1;
                demo->extension_names[demo->enabled_extension_count++] = VK_KHR_WIN32_SURFACE_EXTENSION_NAME;
            }
            if (!strcmp(VK_EXT_DEBUG_UTILS_EXTENSION_NAME, instance_extensions[i].extensionName)) {
                if (demo->validate) {
                    demo->extension_names[demo->enabled_extension_count++] =
                        VK_EXT_DEBUG_UTILS_EXTENSION_NAME;
                }
            }
            assert(demo->enabled_extension_count < 64);
        }

        free(instance_extensions);
    }

    const VkApplicationInfo app = {
        .sType = VK_STRUCTURE_TYPE_APPLICATION_INFO,
        .pNext = NULL,
        .pApplicationName = APP_SHORT_NAME,
        .applicationVersion = 0,
        .pEngineName = APP_SHORT_NAME,
        .engineVersion = 0,
        .apiVersion = VK_API_VERSION_1_0,
    };
    VkInstanceCreateInfo inst_info = {
        .sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO,
        .pNext = NULL,
        .pApplicationInfo = &app,
        .enabledLayerCount = demo->enabled_layer_count,
        .ppEnabledLayerNames = (const char* const*)instance_validation_layers,
        .enabledExtensionCount = demo->enabled_extension_count,
        .ppEnabledExtensionNames = (const char* const*)demo->extension_names,
    };

    /*
     * This is info for a temp callback to use during CreateInstance.
     * After the instance is created, we use the instance-based
     * function to register the final callback.
     */
    VkDebugUtilsMessengerCreateInfoEXT dbg_messenger_create_info;
    if (demo->validate) {
        // VK_EXT_debug_utils style
        dbg_messenger_create_info.sType = VK_STRUCTURE_TYPE_DEBUG_UTILS_MESSENGER_CREATE_INFO_EXT;
        dbg_messenger_create_info.pNext = NULL;
        dbg_messenger_create_info.flags = 0;
        dbg_messenger_create_info.messageSeverity =
            VK_DEBUG_UTILS_MESSAGE_SEVERITY_WARNING_BIT_EXT | VK_DEBUG_UTILS_MESSAGE_SEVERITY_ERROR_BIT_EXT;
        dbg_messenger_create_info.messageType = VK_DEBUG_UTILS_MESSAGE_TYPE_GENERAL_BIT_EXT |
                                                VK_DEBUG_UTILS_MESSAGE_TYPE_VALIDATION_BIT_EXT |
                                                VK_DEBUG_UTILS_MESSAGE_TYPE_PERFORMANCE_BIT_EXT;
        dbg_messenger_create_info.pfnUserCallback = debug_messenger_callback;
        dbg_messenger_create_info.pUserData = demo;
        inst_info.pNext = &dbg_messenger_create_info;
    }

    uint32_t gpu_count;

    err = vkCreateInstance(&inst_info, NULL, &demo->inst);

    /* Make initial call to query gpu_count, then second call for gpu info*/
    err = vkEnumeratePhysicalDevices(demo->inst, &gpu_count, NULL);

    if (gpu_count > 0) {
        VkPhysicalDevice* physical_devices = malloc(sizeof(VkPhysicalDevice) * gpu_count);
        err = vkEnumeratePhysicalDevices(demo->inst, &gpu_count, physical_devices);

        /* For cube demo we just grab the first physical device */
        demo->gpu = physical_devices[0];
        free(physical_devices);
    }

    /* Look for device extensions */
    uint32_t device_extension_count = 0;
    VkBool32 swapchainExtFound = 0;
    demo->enabled_extension_count = 0;
    memset(demo->extension_names, 0, sizeof(demo->extension_names));

    err = vkEnumerateDeviceExtensionProperties(demo->gpu, NULL, &device_extension_count, NULL);
    assert(!err);

    if (device_extension_count > 0) {
        VkExtensionProperties* device_extensions =
            malloc(sizeof(VkExtensionProperties) * device_extension_count);
        err =
            vkEnumerateDeviceExtensionProperties(demo->gpu, NULL, &device_extension_count, device_extensions);
        assert(!err);

        for (uint32_t i = 0; i < device_extension_count; i++) {
            if (!strcmp(VK_KHR_SWAPCHAIN_EXTENSION_NAME, device_extensions[i].extensionName)) {
                swapchainExtFound = 1;
                demo->extension_names[demo->enabled_extension_count++] = VK_KHR_SWAPCHAIN_EXTENSION_NAME;
            }
            assert(demo->enabled_extension_count < 64);
        }

        free(device_extensions);
    }

    vkGetPhysicalDeviceProperties(demo->gpu, &demo->gpu_props);

    /* Call with NULL data to get count */
    vkGetPhysicalDeviceQueueFamilyProperties(demo->gpu, &demo->queue_family_count, NULL);
    assert(demo->queue_family_count >= 1);

    demo->queue_props =
        (VkQueueFamilyProperties*)malloc(demo->queue_family_count * sizeof(VkQueueFamilyProperties));
    vkGetPhysicalDeviceQueueFamilyProperties(demo->gpu, &demo->queue_family_count, demo->queue_props);
}

static void
demo_create_device(struct demo* demo)
{
    VkResult U_ASSERT_ONLY err;
    float queue_priorities[1] = { 0.0 };
    VkDeviceQueueCreateInfo queues[2];
    queues[0].sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
    queues[0].pNext = NULL;
    queues[0].queueFamilyIndex = demo->graphics_queue_family_index;
    queues[0].queueCount = 1;
    queues[0].pQueuePriorities = queue_priorities;
    queues[0].flags = 0;

    VkDeviceCreateInfo device = {
        .sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO,
        .pNext = NULL,
        .queueCreateInfoCount = 1,
        .pQueueCreateInfos = queues,
        .enabledLayerCount = 0,
        .ppEnabledLayerNames = NULL,
        .enabledExtensionCount = demo->enabled_extension_count,
        .ppEnabledExtensionNames = (const char* const*)demo->extension_names,
        .pEnabledFeatures = NULL, // If specific features are required, pass them in here
    };
    if (demo->separate_present_queue) {
        queues[1].sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
        queues[1].pNext = NULL;
        queues[1].queueFamilyIndex = demo->present_queue_family_index;
        queues[1].queueCount = 1;
        queues[1].pQueuePriorities = queue_priorities;
        queues[1].flags = 0;
        device.queueCreateInfoCount = 2;
    }
    err = vkCreateDevice(demo->gpu, &device, NULL, &demo->device);
    assert(!err);
}

static void
demo_init_vk_swapchain(struct demo* demo)
{
    VkResult U_ASSERT_ONLY err;

    // Create a WSI surface for the window:
    assert(!err);

    // Iterate over each queue to learn whether it supports presenting:
    VkBool32* supportsPresent = (VkBool32*)malloc(demo->queue_family_count * sizeof(VkBool32));
    for (uint32_t i = 0; i < demo->queue_family_count; i++) {
        vkGetPhysicalDeviceSurfaceSupportKHR(demo->gpu, i, demo->surface, &supportsPresent[i]);
    }

    // Search for a graphics and a present queue in the array of queue
    // families, try to find one that supports both
    uint32_t graphicsQueueFamilyIndex = UINT32_MAX;
    uint32_t presentQueueFamilyIndex = UINT32_MAX;
    for (uint32_t i = 0; i < demo->queue_family_count; i++) {
        if ((demo->queue_props[i].queueFlags & VK_QUEUE_GRAPHICS_BIT) != 0) {
            if (graphicsQueueFamilyIndex == UINT32_MAX) {
                graphicsQueueFamilyIndex = i;
            }

            if (supportsPresent[i] == VK_TRUE) {
                graphicsQueueFamilyIndex = i;
                presentQueueFamilyIndex = i;
                break;
            }
        }
    }

    if (presentQueueFamilyIndex == UINT32_MAX) {
        // If didn't find a queue that supports both graphics and present, then
        // find a separate present queue.
        for (uint32_t i = 0; i < demo->queue_family_count; ++i) {
            if (supportsPresent[i] == VK_TRUE) {
                presentQueueFamilyIndex = i;
                break;
            }
        }
    }

    // Generate error if could not find both a graphics and a present queue
    if (graphicsQueueFamilyIndex == UINT32_MAX || presentQueueFamilyIndex == UINT32_MAX) {
        ERR_EXIT("Could not find both graphics and present queues\n", "Swapchain Initialization Failure");
    }

    demo->graphics_queue_family_index = graphicsQueueFamilyIndex;
    demo->present_queue_family_index = presentQueueFamilyIndex;
    demo->separate_present_queue = (demo->graphics_queue_family_index != demo->present_queue_family_index);
    free(supportsPresent);

    demo_create_device(demo);

    vkGetDeviceQueue(demo->device, demo->graphics_queue_family_index, 0, &demo->graphics_queue);

    if (!demo->separate_present_queue) {
        demo->present_queue = demo->graphics_queue;
    } else {
        vkGetDeviceQueue(demo->device, demo->present_queue_family_index, 0, &demo->present_queue);
    }

    // Get the list of VkFormat's that are supported:
    uint32_t formatCount;
    err = vkGetPhysicalDeviceSurfaceFormatsKHR(demo->gpu, demo->surface, &formatCount, NULL);
    assert(!err);
    VkSurfaceFormatKHR* surfFormats = (VkSurfaceFormatKHR*)malloc(formatCount * sizeof(VkSurfaceFormatKHR));
    err = vkGetPhysicalDeviceSurfaceFormatsKHR(demo->gpu, demo->surface, &formatCount, surfFormats);
    assert(!err);
    // If the format list includes just one entry of VK_FORMAT_UNDEFINED,
    // the surface has no preferred format.  Otherwise, at least one
    // supported format will be returned.
    if (formatCount == 1 && surfFormats[0].format == VK_FORMAT_UNDEFINED) {
        demo->format = VK_FORMAT_B8G8R8A8_UNORM;
    } else {
        assert(formatCount >= 1);
        demo->format = surfFormats[0].format;
    }
    demo->color_space = surfFormats[0].colorSpace;
    free(surfFormats);

    demo->quit = false;

    // Create semaphores to synchronize acquiring presentable buffers before
    // rendering and waiting for drawing to be complete before presenting
    VkSemaphoreCreateInfo semaphoreCreateInfo = {
        .sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO,
        .pNext = NULL,
        .flags = 0,
    };

    // Create fences that we can use to throttle if we get too far
    // ahead of the image presents
    VkFenceCreateInfo fence_ci = { .sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO,
                                   .pNext = NULL,
                                   .flags = VK_FENCE_CREATE_SIGNALED_BIT };
    for (uint32_t i = 0; i < FRAME_LAG; i++) {
        err = vkCreateFence(demo->device, &fence_ci, NULL, &demo->fences[i]);
        assert(!err);

        err =
            vkCreateSemaphore(demo->device, &semaphoreCreateInfo, NULL, &demo->image_acquired_semaphores[i]);
        assert(!err);

        err = vkCreateSemaphore(demo->device, &semaphoreCreateInfo, NULL, &demo->draw_complete_semaphores[i]);
        assert(!err);

        if (demo->separate_present_queue) {
            err = vkCreateSemaphore(demo->device, &semaphoreCreateInfo, NULL,
                                    &demo->image_ownership_semaphores[i]);
            assert(!err);
        }
    }
    demo->frame_index = 0;

    // Get Memory information and properties
    vkGetPhysicalDeviceMemoryProperties(demo->gpu, &demo->memory_properties);
}

static void
demo_init(struct demo* demo, int argc, char** argv)
{
    vec3 eye = { 0.0f, 3.0f, 5.0f };
    vec3 origin = { 0, 0, 0 };
    vec3 up = { 0.0f, 1.0f, 0.0 };

    memset(demo, 0, sizeof(*demo));
    demo->presentMode = VK_PRESENT_MODE_FIFO_KHR;

    demo_init_vk(demo);

    demo->width = 500;
    demo->height = 500;

    demo->spin_angle = 4.0f;
    demo->spin_increment = 0.2f;
    demo->pause = false;

    mat4x4_perspective(demo->projection_matrix, (float)degreesToRadians(45.0f), 1.0f, 0.1f, 100.0f);
    mat4x4_look_at(demo->view_matrix, eye, origin, up);
    mat4x4_identity(demo->model_matrix);

    demo->projection_matrix[1][1] *= -1; // Flip projection matrix from GL to Vulkan orientation.
}

int
main(int argc, char** argv)
{
    struct demo demo;

    demo_init(&demo, argc, argv);
    demo_init_vk_swapchain(&demo);
    demo_prepare(&demo);

    demo_run();

    demo_cleanup(&demo);

    return validation_error;
}