Improved openGL and ImGUI implementation

imgui.ini

@@ -1,8 +0,0 @@
-[Window][Debug##Default]
-Pos=60,60
-Size=400,400
-
-[Window][Settings]
-Pos=60,60
-Size=170,48
-

include/io.h

@@ -6,7 +6,7 @@
 extern "C" {
 #endif
 
-char* readFile(const char* filePath);
+char* read_file(const char* filePath);
 
 #ifdef __cplusplus
 }

include/main.h

@@ -0,0 +1,8 @@
+#ifndef MAIN_H
+#define MAIN_H
+
+#include <glad/glad.h> // Include GLAD before GLFW
+#include <GLFW/glfw3.h>
+#include <iostream>
+
+#endif // MAIN_H

source/io.c

@@ -1,6 +1,6 @@
 #include "io.h"
 
-char* readFile(const char* filePath) {
+char* read_file(const char* filePath) {
     FILE* file = fopen(filePath, "rb");
     if (file == NULL) {
         fprintf(stderr, "Error: Could not open file %s\n", filePath);

source/main.cpp

@@ -1,7 +1,4 @@
-#include <glad/glad.h> // Include GLAD before GLFW
-#include <GLFW/glfw3.h>
-#include <iostream>
-
+#include "main.h"
 #include "io.h"
 
 // ImGui includes
@@ -9,103 +6,124 @@
 #include "imgui/imgui_impl_glfw.h"
 #include "imgui/imgui_impl_opengl3.h"
 
-char* fragmentShaderFile = "./source/shader/fragment.glsl";
-char* vertexShaderFile = "./source/shader/vertex.glsl";
+const char FRAGMENT_SHADER_SOURCE[] = "./source/shader/fragment.glsl";
+const char VERTEX_SHADER_SOURCE[] = "./source/shader/vertex.glsl";
+
+const char PROGRAM_NAME[] = "ImGui OpenGL Example";
 
 const unsigned int SCR_WIDTH = 1920;
 const unsigned int SCR_HEIGHT = 1080;
+const char *glsl_version;
 
-// Callback to resize the viewport when the window is resized
-void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
-	(void)window; // Unused parameter
-	glViewport(0, 0, width, height);
-}
+GLFWwindow *window;
+unsigned int VBO, VAO;
+unsigned int shader;
 
-int main() {
-	glfwInit();
+__attribute__((constructor)) static void init_glfw(void) {
+	if (!glfwInit()) {
+		fprintf(stderr, "GLFW initialization failed\n");
+		abort(); // program cannot continue
+	}
+#ifdef __APPLE__
+	glsl_version = "#version 330";
+	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Required on Mac
+#else
+	glsl_version = "#version 130";
+#endif
 	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
 	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
 	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
 
-#ifdef __APPLE__
-    const char* glsl_version = "#version 330";
-    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Required on Mac
-#endif
-
-	GLFWwindow *window = glfwCreateWindow( SCR_WIDTH, SCR_HEIGHT , "OpenGLTemplate", NULL, NULL);
+	window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, PROGRAM_NAME, NULL, NULL);
 	if (window == NULL) {
-		std::cout << "Failed to create GLFW window" << std::endl;
 		glfwTerminate();
-		return -1;
+		fprintf(stderr, "Failed to create GLFW window\n");
+		abort(); // program cannot continue
 	}
+
 	glfwMakeContextCurrent(window);
-	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
+	glfwSwapInterval(1); // Enable vsync
 
-	if (!gladLoadGLLoader(reinterpret_cast<GLADloadproc>(glfwGetProcAddress))) {
+	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
 		std::cout << "Failed to initialize GLAD" << std::endl;
-		return -1;
+		glfwTerminate();
 	}
+	glGenBuffers(1, &VBO);
+	glBindBuffer(GL_ARRAY_BUFFER, VBO);
 
-    // Compile shaders
-    char* vertexShaderSource = readFile(vertexShaderFile);
-    char* fragmentShaderSource = readFile(fragmentShaderFile);
+	glGenVertexArrays(1, &VAO);
+	glBindVertexArray(VAO);
+	glBindBuffer(GL_ARRAY_BUFFER, VBO);
 
-    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
-    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
-    glCompileShader(vertexShader);
+	glEnableVertexAttribArray(0);
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *)0);
 
-    unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
-    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
-    glCompileShader(fragmentShader);
+	char *vertex_shader_source = read_file(VERTEX_SHADER_SOURCE);
+	char *fragment_shader_source = read_file(FRAGMENT_SHADER_SOURCE);
 
-    unsigned int shaderProgram = glCreateProgram();
-    glAttachShader(shaderProgram, vertexShader);
-    glAttachShader(shaderProgram, fragmentShader);
-    glLinkProgram(shaderProgram);
+	unsigned int vertex_shader = glCreateShader(GL_VERTEX_SHADER);
+	glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);
+	glCompileShader(vertex_shader);
 
-    glDeleteShader(vertexShader);
-    glDeleteShader(fragmentShader);
+	unsigned int fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
+	glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);
+	glCompileShader(fragment_shader);
 
-    delete[] vertexShaderSource;
-    delete[] fragmentShaderSource;
+	shader = glCreateProgram();
+	glAttachShader(shader, vertex_shader);
+	glAttachShader(shader, fragment_shader);
+	glLinkProgram(shader);
 
-    // --- ImGui Setup Start ---
+	glDeleteShader(vertex_shader);
+	glDeleteShader(fragment_shader);
+
+	free(vertex_shader_source);
+	free(fragment_shader_source);
+}
+
+__attribute__((destructor)) static void shutdown_glfw(void) {
+	glDeleteVertexArrays(1, &VAO);
+	glDeleteBuffers(1, &VBO);
+	glfwDestroyWindow(window);
+	glfwTerminate();
+}
+
+static inline void init_imgui() {
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
-	ImGuiIO &io = ImGui::GetIO();
-	(void)io;
     ImGui::StyleColorsDark();
     ImGui_ImplGlfw_InitForOpenGL(window, true);
     ImGui_ImplOpenGL3_Init(glsl_version);
+}
+
+int main() {
+    init_imgui();
 
 	while (!glfwWindowShouldClose(window)) {
-		if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
-			glfwSetWindowShouldClose(window, true);
+		// Poll events
+		glfwPollEvents();
 
+		// Start ImGui frame
 		ImGui_ImplOpenGL3_NewFrame();
 		ImGui_ImplGlfw_NewFrame();
 		ImGui::NewFrame();
 
-        ImGui::Begin("Settings");
+		// Create ImGui window
+		ImGui::Begin("Debug");
 		ImGui::Text("FPS: %.1f", static_cast<double>(ImGui::GetIO().Framerate));
 		ImGui::End();
-        glUseProgram(shaderProgram);
-
-		glClearColor(0.01f, 0.01f, 0.01f, 1.0f); // Set clear color (Dark Gray)
-		glClear(GL_COLOR_BUFFER_BIT);         // Clear the screen
 
+		// Render
+		glClearColor(0.03f, 0.03f, 0.03f, 1.0f);
+		glClear(GL_COLOR_BUFFER_BIT);
 
+		// Render ImGui
 		ImGui::Render();
 		ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
 
+		// Swap buffers
 		glfwSwapBuffers(window);
-		glfwPollEvents();
 	}
 
-	// 5. Clean up
-    ImGui_ImplOpenGL3_Shutdown();
-    ImGui_ImplGlfw_Shutdown();
-    ImGui::DestroyContext();
-	glfwTerminate();
 	return 0;
 }