Add HelloWorld.java

modules/samples/src/main/java/overrungl/demo/opengl/HelloWorld.java

@@ -0,0 +1,134 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2024 Overrun Organization
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ */
+
+import overrun.marshal.Unmarshal;
+import overrungl.glfw.GLFW;
+import overrungl.glfw.GLFWCallbacks;
+import overrungl.glfw.GLFWErrorCallback;
+import overrungl.opengl.GL;
+import overrungl.opengl.GLLoader;
+
+import java.lang.foreign.MemorySegment;
+import java.util.Objects;
+
+final int INIT_WIDTH = 300;
+final int INIT_HEIGHT = 300;
+
+final GLFW glfw = GLFW.INSTANCE;
+// The window handle
+MemorySegment window = MemorySegment.NULL;
+// The OpenGL context
+GL gl = null;
+
+void start() {
+    // Set up an error callback. The default implementation
+    // will print the error message in System.err.
+    GLFWErrorCallback.createPrint().set();
+
+    // Initialize GLFW. Most GLFW functions will not work before doing this.
+    // If you are using Kotlin, you can use the builtin check function
+    if (!glfw.init()) {
+        throw new IllegalStateException("Failed to initialize GLFW");
+    }
+
+    // Configure GLFW
+    // optional, the current window hints are already the default
+    glfw.defaultWindowHints();
+    // the window will be resizable
+    glfw.windowHint(GLFW.RESIZABLE, true);
+
+    // Get the resolution of the primary monitor
+    var vidMode = glfw.getVideoMode(glfw.getPrimaryMonitor());
+    if (vidMode != null) {
+        // Center the window
+        glfw.windowHint(GLFW.POSITION_X, (vidMode.width() - INIT_WIDTH) / 2);
+        glfw.windowHint(GLFW.POSITION_Y, (vidMode.height() - INIT_HEIGHT) / 2);
+    }
+
+    // Create the window
+    window = glfw.createWindow(INIT_WIDTH, INIT_HEIGHT, "Hello World!", MemorySegment.NULL, MemorySegment.NULL);
+    if (Unmarshal.isNullPointer(window)) {
+        throw new IllegalStateException("Failed to create the GLFW window");
+    }
+
+    // Set up a key callback. It will be called every time a key is pressed, repeated or released.
+    glfw.setKeyCallback(window, (handle, key, _, action, _) -> {
+        if (key == GLFW.KEY_ESCAPE && action == GLFW.RELEASE) {
+            // We will detect this in the rendering loop
+            glfw.setWindowShouldClose(handle, true);
+        }
+    });
+    glfw.setFramebufferSizeCallback(window, (_, width, height) -> {
+        // Resize the viewport
+        if (gl != null) {
+            gl.viewport(0, 0, width, height);
+        }
+    });
+
+    // Make the OpenGL context current
+    glfw.makeContextCurrent(window);
+    // Enable v-sync
+    glfw.swapInterval(1);
+
+    // Load OpenGL capabilities with GLFW.
+    // The default loading function uses a forward compatible profile,
+    // which cannot access deprecated and removed functions.
+    gl = Objects.requireNonNull(GLLoader.load(GLLoader.loadFlags(glfw::getProcAddress)), "Failed to load OpenGL");
+    initGL(gl);
+
+    run();
+}
+
+void initGL(GL gl) {
+    // Set the clear color
+    gl.clearColor(0.4f, 0.6f, 0.9f, 1.0f);
+}
+
+void run() {
+    // Run the rendering loop until the user has attempted to close
+    // the window or has pressed the ESCAPE key.
+    while (!glfw.windowShouldClose(window)) {
+        // Poll for window events. The key callback above will only be
+        // invoked during this call.
+        glfw.pollEvents();
+        render(gl);
+    }
+}
+
+void render(GL gl) {
+    // clear the framebuffer
+    gl.clear(GL.COLOR_BUFFER_BIT | GL.DEPTH_BUFFER_BIT);
+    // swap the color buffers
+    glfw.swapBuffers(window);
+}
+
+void dispose() {
+    // Free the window callbacks and destroy the window
+    GLFWCallbacks.free(window);
+    glfw.destroyWindow(window);
+
+    // Terminate GLFW and remove the error callback
+    glfw.terminate();
+    glfw.setErrorCallback(null);
+}
+
+void main() {
+    try {
+        start();
+    } finally {
+        dispose();
+    }
+}