example_beginend_shader_1.cpp

#include <stdafx.h>

// OpenGL
#include <GL/glew.h>
#include <GL/gl.h>
#include <GL/glu.h>

// glm
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

// glfw
#include <GLFW/glfw3.h>

// stl
#include <vector>
#include <stdexcept>
#include <array>
#include <map>
#include <tuple>
#include <algorithm>
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>

#define _USE_MATH_DEFINES
#include <math.h>

// project includes
#include <gl/gl_debug.h>
#include <gl/gl_shader.h>

// preprocessor definitions

#ifndef M_PI
#define M_PI 3.14159265358979323846 
#endif


std::string sh_vert = R"(
#version 120

varying vec2 texcoord;

void main(void)
{
  gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
  texcoord = gl_MultiTexCoord0.xy;
} 
)";

std::string sh_frag = R"(
#version 120

varying vec2 texcoord;

uniform sampler2D texture;

void main(void)
{
    vec4 texcolor = texture2D(texture, texcoord);
    gl_FragColor = texcolor.gbra;
}
)";


int main(void)
{
    if ( glfwInit() == 0 )
        throw std::runtime_error( "error initializing glfw" );

    GLFWwindow *wnd = glfwCreateWindow( 800, 600, "OGL window", nullptr, nullptr );
    if ( wnd == nullptr )
    {
        glfwTerminate();
        throw std::runtime_error( "error initializing window" ); 
    }

    glfwMakeContextCurrent(wnd);

    if ( glewInit() != GLEW_OK )
        throw std::runtime_error( "error initializing glew" );

    OpenGL::CContext::TDebugLevel debug_level = OpenGL::CContext::TDebugLevel::all;
    OpenGL::CContext context;
    context.Init( debug_level );

    OpenGL::ShaderProgramSimple prog(
    {
      { sh_vert, GL_VERTEX_SHADER },
      { sh_frag, GL_FRAGMENT_SHADER }
    } );

    GLint tex_loc = glGetUniformLocation( prog.Prog(), "texture" );
    prog.Use();
    glUniform1i(tex_loc, 0);

    GLuint tex_obj;
    glGenTextures( 1, &tex_obj );
    unsigned char tex_data[] = { 255, 0, 0, 255, 0, 255, 0, 255, 0, 0, 255, 255, 255, 255, 0, 255 };
    glBindTexture( GL_TEXTURE_2D, tex_obj );
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, tex_data);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();

    //glEnable( GL_TEXTURE_2D );

    while (!glfwWindowShouldClose(wnd))
    {
        glBegin( GL_QUADS );
        glTexCoord2d( 0.0, 0.0 );
        glVertex2d( -0.5, -0.5 );
        glTexCoord2d( 0.0, 1.0 );
        glVertex2d( -0.5, 0.5 );
        glTexCoord2d( 1.0, 1.0 );
        glVertex2d( 0.5, 0.5 );
        glTexCoord2d( 1.0, 0.0 );
        glVertex2d( 0.5, -0.5 );
        glEnd();

        glfwSwapBuffers(wnd);
        glfwPollEvents();
    }

    glfwDestroyWindow( wnd );
    wnd = nullptr;
    glfwTerminate();

    return 0;
}