main.cpp

#include <iostream>
#include <cmath>

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

// GLEW
#define GLEW_STATIC

#include <GL/glew.h>

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

#include "shader.h"
#include "camera.h"


#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);

// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

// camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX = SCR_WIDTH / 2.0f;
float lastY = SCR_HEIGHT / 2.0f;
bool firstMouse = true;

// timing
float deltaTime = 0.0f;
float lastFrame = 0.0f;

// lighting
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);

GLFWwindow* createWindow () {
    std::cout << "Starting GLFW context, OpenGL 3.3" << std::endl;
    // Init GLFW
    glfwInit();
    // Set all the required options for GLFW
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_RESIZABLE, GL_TRUE);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);


    // Create a GLFW window object that we can use for GLFW's functions
    GLFWwindow *window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "Window the great", nullptr, nullptr);
    if (window == nullptr) {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        exit(-1);
    }
    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    glfwSetCursorPosCallback(window, mouse_callback);
    glfwSetScrollCallback(window, scroll_callback);

    // tell GLFW to capture our mouse
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    // configure global opengl state
    // -----------------------------
    glEnable(GL_DEPTH_TEST);

    // Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
    glewExperimental = GL_TRUE;
    // Initialize GLEW to setup the OpenGL Function pointers
    if (glewInit() != GLEW_OK) {
        std::cout << "Failed to initialize GLEW" << std::endl;
        exit(-1);
    }

    return window;
}

int main() {
    GLFWwindow* window = createWindow();

    // build and compile our shader zprogram
    // ------------------------------------
    Shader lightingShader("../shaders/1.colors.vs", "../shaders/1.colors.fs");
    Shader lampShader("../shaders/1.lamp.vs", "../shaders/1.lamp.fs");

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------
    float vertices[] = {
            -0.5f, -0.5f, -0.5f,
            0.5f, -0.5f, -0.5f,
            0.5f,  0.5f, -0.5f,
            0.5f,  0.5f, -0.5f,
            -0.5f,  0.5f, -0.5f,
            -0.5f, -0.5f, -0.5f,

            -0.5f, -0.5f,  0.5f,
            0.5f, -0.5f,  0.5f,
            0.5f,  0.5f,  0.5f,
            0.5f,  0.5f,  0.5f,
            -0.5f,  0.5f,  0.5f,
            -0.5f, -0.5f,  0.5f,

            -0.5f,  0.5f,  0.5f,
            -0.5f,  0.5f, -0.5f,
            -0.5f, -0.5f, -0.5f,
            -0.5f, -0.5f, -0.5f,
            -0.5f, -0.5f,  0.5f,
            -0.5f,  0.5f,  0.5f,

            0.5f,  0.5f,  0.5f,
            0.5f,  0.5f, -0.5f,
            0.5f, -0.5f, -0.5f,
            0.5f, -0.5f, -0.5f,
            0.5f, -0.5f,  0.5f,
            0.5f,  0.5f,  0.5f,

            -0.5f, -0.5f, -0.5f,
            0.5f, -0.5f, -0.5f,
            0.5f, -0.5f,  0.5f,
            0.5f, -0.5f,  0.5f,
            -0.5f, -0.5f,  0.5f,
            -0.5f, -0.5f, -0.5f,

            -0.5f,  0.5f, -0.5f,
            0.5f,  0.5f, -0.5f,
            0.5f,  0.5f,  0.5f,
            0.5f,  0.5f,  0.5f,
            -0.5f,  0.5f,  0.5f,
            -0.5f,  0.5f, -0.5f,
    };
    // first, configure the cube's VAO (and VBO)
    unsigned int VBO, cubeVAO;
    glGenVertexArrays(1, &cubeVAO);
    glGenBuffers(1, &VBO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glBindVertexArray(cubeVAO);

    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    // second, configure the light's VAO (VBO stays the same; the vertices are the same for the light object which is also a 3D cube)
    unsigned int lightVAO;
    glGenVertexArrays(1, &lightVAO);
    glBindVertexArray(lightVAO);

    // we only need to bind to the VBO (to link it with glVertexAttribPointer), no need to fill it; the VBO's data already contains all we need (it's already bound, but we do it again for educational purposes)
    glBindBuffer(GL_ARRAY_BUFFER, VBO);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);


    // render loop
    // -----------
    while (!glfwWindowShouldClose(window))
    {
        // per-frame time logic
        // --------------------
        float currentFrame = glfwGetTime();
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;

        // input
        // -----
        processInput(window);

        // render
        // ------
        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        // be sure to activate shader when setting uniforms/drawing objects
        lightingShader.use();
        lightingShader.setVec3("objectColor", 1.0f, 0.5f, 0.31f);
        lightingShader.setVec3("lightColor",  1.0f, 1.0f, 1.0f);

        // view/projection transformations
        glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
        glm::mat4 view = camera.GetViewMatrix();
        lightingShader.setMat4("projection", projection);
        lightingShader.setMat4("view", view);

        // world transformation
        glm::mat4 model;
        lightingShader.setMat4("model", model);

        // render the cube
        glBindVertexArray(cubeVAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);


        // also draw the lamp object
        lampShader.use();
        lampShader.setMat4("projection", projection);
        lampShader.setMat4("view", view);
        model = glm::mat4();
        model = glm::translate(model, lightPos);
        model = glm::scale(model, glm::vec3(0.2f)); // a smaller cube
        lampShader.setMat4("model", model);

        glBindVertexArray(lightVAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);


        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
        // -------------------------------------------------------------------------------
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // optional: de-allocate all resources once they've outlived their purpose:
    // ------------------------------------------------------------------------
    glDeleteVertexArrays(1, &cubeVAO);
    glDeleteVertexArrays(1, &lightVAO);
    glDeleteBuffers(1, &VBO);

    // glfw: terminate, clearing all previously allocated GLFW resources.
    // ------------------------------------------------------------------
    glfwTerminate();
    return 0;
}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);

    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
        camera.ProcessKeyboard(FORWARD, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
        camera.ProcessKeyboard(BACKWARD, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
        camera.ProcessKeyboard(LEFT, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
        camera.ProcessKeyboard(RIGHT, deltaTime);
}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    // make sure the viewport matches the new window dimensions; note that width and
    // height will be significantly larger than specified on retina displays.
    glViewport(0, 0, width, height);
}


// glfw: whenever the mouse moves, this callback is called
// -------------------------------------------------------
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
    if (firstMouse)
    {
        lastX = xpos;
        lastY = ypos;
        firstMouse = false;
    }

    float xoffset = xpos - lastX;
    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top

    lastX = xpos;
    lastY = ypos;

    camera.ProcessMouseMovement(xoffset, yoffset);
}

// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
    camera.ProcessMouseScroll(yoffset);
}