Hello Triangle in OpenGL

#include <iostream>

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

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow *window);

// Variables for checking compilation/linking correctness
int success;
char infoLog[512];

// Basic vertex shader in GLSL (OpenGL Shading Language)
const char *vertexShaderSource =
"#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"void main() {\n"
"	gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"}\0";

// Basic fragment shader
const char *fragmentShaderSource =
"#version 330 core\n"
"out vec4 FragColor;\n"
"void main() {\n"
"	FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
"}\0";

int main() {
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
	if (window == NULL) {
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}
	glViewport(0, 0, 800, 600);
	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

	// 1. Build and compile our shader programs

	// Create a vertex shader object
	unsigned int vertexShader;
	vertexShader = glCreateShader(GL_VERTEX_SHADER);

	// Attach the shader source code to the shader object
	glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);

	// Compile the vertex shader dynamically 
	glCompileShader(vertexShader);

	// Check if compilation was successful
	glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n";
		std::cout << infoLog << std::endl;
	}

	// Create a fragment shader object
	unsigned int fragmentShader;
	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);

	// Attach the shader source code to the shader object
	glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);

	// Compile the fragment shader dynamically
	glCompileShader(fragmentShader);
	glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n";
		std::cout << infoLog << std::endl;
	}


	// 2. Link shaders

	// Create a shader program
	unsigned int shaderProgram;
	shaderProgram = glCreateProgram();

	// Attach the compiled shaders to the shader program
	glAttachShader(shaderProgram, vertexShader);
	glAttachShader(shaderProgram, fragmentShader);
	glLinkProgram(shaderProgram);

	// Check if linking was successful
	glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
	if (!success) {
		glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
		std::cout << "ERROR::PROGRAM::LINKING_FAILED\n";
		std::cout << infoLog << std::endl;
	}

	// Delete shader objects if we no longer need them anymore
	glDeleteShader(vertexShader);
	glDeleteShader(fragmentShader);


	// 3. Set up vertex data and configure vertex attributes

	// Define three vertices with 3D positions
	float vertices[] = {
		-0.5f, -0.5f, 0.0f,
		0.5f, -0.5f, 0.0f,
		0.0f,  0.5f, 0.0f
	};

	// Generate vertex buffer object (VBO) and vertex array object (VAO)
	unsigned int VBO, VAO;
	glGenVertexArrays(1, &VAO);
	glGenBuffers(1, &VBO);

	// Bind VAO, then bind VBO
	glBindVertexArray(VAO);
	glBindBuffer(GL_ARRAY_BUFFER, VBO);

	// Copy the vertex data into the buffer's memory
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

	// Set attributes that describe how OpenGL should interpret the vertex data
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(0);


	// Unbind so other calls won't modify VBO and VAO
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindVertexArray(0);

	while (!glfwWindowShouldClose(window)) {
		processInput(window);

		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);

		glUseProgram(shaderProgram);
		glBindVertexArray(VAO);
		glDrawArrays(GL_TRIANGLES, 0, 3);

		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	glfwTerminate();

	return 0;
}

void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
	glViewport(0, 0, width, height);
}

void processInput(GLFWwindow *window) {
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);
}