engineer-thesis-WUT/Engine/engine/beforeRender.cpp

#ifndef BEFORE_RENDER_CPP
#define BEFORE_RENDER_CPP
#include <glad/glad.h>
#include <GLFW/glfw3.h>

#include <iostream>
#include "beforeRender.hpp"
#include "constants.hpp"
#include "misc.hpp"

void configureGLFW(const int GLFWMajorVersion, const int GLFWMinorVersion)
{
    // first argument tells us what option to configure
    // second is to what we set the value of this option
    // see: https://www.glfw.org/docs/latest/window.html#window_hints
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, GLFWMajorVersion);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, GLFWMinorVersion);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
// we set GLFW to 3.3 CORE
// core profile gives us access to smaller subset of OGL without backwards compatible features

// if we are on Mac OS X we need this for our code to work
#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
}

void instantiateGLFWwindow()
{
    // Initialize GLFW
    glfwInit();
    configureGLFW(constants::GLFW_MAJOR_VERSION, constants::GLFW_MINOR_VERSION);
}

GLFWwindow *createWindowObject()
{
    // First two arguments are width and height
    // Third is the name of the window
    // We ignore last two
    GLFWwindow *window = glfwCreateWindow(constants::MAIN_WINDOW_WIDTH, constants::MAIN_WINDOW_HEIGHT, constants::MAIN_WINDOW_NAME, NULL, NULL);
    return window;
}

int initializeGLAD()
{
    // we load address of OGL OS-specific function pointers
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        print("Failed to initialize GLAD");
        return -1;
    }
    return 0;
}

// resizes viewport when user resizes window
void framebuffer_size_callback(GLFWwindow *window, const int width, const int height)
{
    glViewport(0, 0, width, height);
}

void viewPort(GLFWwindow *window)
{
    // We tell OGL size of rendering window
    // First two define left corner of window
    // 3th and 4th width and height of rendering window
    // we could set them to be smaller than window dimension, ogl rendering will be then displayed in smaller window
    glViewport(0, 0, constants::MAIN_WINDOW_WIDTH, constants::MAIN_WINDOW_HEIGHT);
    // processed coordinates are between -1 and 1 so here we map:
    // (-1 to 1) to (0, constants::MAIN_WINDOW_WIDTH) and (0, constants::MAIN_WINDOW_HEIGHT)
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    // we call framebuffer_size_callback on every window resize
}

GLFWwindow *prepareForRender()
{
    instantiateGLFWwindow();

    GLFWwindow *window = createWindowObject();
    // function returns GLFWWindow object

    if (window == NULL)
    {
        print("Failed to create GLFW window");
        glfwTerminate();
        return window;
    }
    // we make context of this window main context of current thread
    glfwMakeContextCurrent(window);

    if (initializeGLAD() == -1)
        return NULL;
    viewPort(window);
    return window;
}

#endif