main.cpp

#include <iostream>

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

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

// screen configs
const unsigned int SCR_WIDTH=800;
const unsigned int SCR_HEIGHT=600;

// vertex shader source
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";

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

int main()
{
    // glfw: init and config
    // ------------------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    // setting up forward compatibility for mac
    #ifdef __APPLE__
        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    #endif

    // glfw: creating window
    // ------------------------
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "OpenGLSandbox", NULL, NULL);

    if (window == NULL) {
        std::cout<<"Failed to create GLFW window"<<std::endl;
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

    // glad: loading fuunction pointers
    // -----------------------------------
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }   

    // building and compiling shaders
    // ------------------------------

    // vector shader
    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    // checking for shader compile error
    int success; char infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if(!success){
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout<<"ERROR::SHADER::VECTOR::COMPILATION_FAILED\n"<<infoLog<<std::endl;
    }

    // fragment shader
    unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    // checking for shader compile error
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
    if(!success){
        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
        std::cout<<"ERROR::SHADER::FRAGMENT::COMPILATION_ERROR\n"<<infoLog<<std::endl;
    }

    // render loop
    // ---------------------------------
    while(!glfwWindowShouldClose(window)) {
        // processing inputs
        processInput(window);

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

        // glfw; swap buffers and listen to IO events
        glfwSwapBuffers(window);
        glfwPollEvents();
    }  

    // glfw: terminate and clear all allocated resources
    // -------------------------------------------------
    glfwTerminate();
  
    return 0;
}

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

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