transform.cpp

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

#include "Shader.h"
#include "stb_image.h"

#include<iostream>
#include<algorithm>
#include<cstdint>

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

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
float clamp(float up, float down, float val);

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

float mixParam = 1.0;



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

    #ifdef __APPLE__
        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    #endif

    

    // glfw window creation
    // --------------------
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", 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: load all OpenGL function pointers
    // ---------------------------------------
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // build and compile our shader program
    // ------------------------------------
    Shader shader("transform_shader.vert", "texture_shader.frag"); // you can name your shader files however you like

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------
    float vertices[] = {
        // positions          // colors           // texture coords
        0.5f,  0.5f, 0.0f,   1.0f, 0.0f, 0.0f,   1.0f, 1.0f, // top right
        0.5f, -0.5f, 0.0f,   0.0f, 1.0f, 0.0f,   1.0f, 0.0f, // bottom right
        -0.5f, -0.5f, 0.0f,   0.0f, 0.0f, 1.0f,   0.0f, 0.0f, // bottom left
        -0.5f,  0.5f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f  // top left 
    };

    unsigned int indices[] = {
        0, 1, 3,
        1, 2, 3
    };

    unsigned int VBO, VAO, EBO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);
    glBindVertexArray(VAO);

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

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    // set attributes for vertex shader
    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // color attribute
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    // texture attribute
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);


    // initialize texture object
    unsigned int texture0;
    glGenTextures(1, &texture0);
    glBindTexture(GL_TEXTURE_2D, texture0);     // all upcoming GL_TEXTURE_2D operations have effect on this object
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // texture filtering
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    // load image, create texture, generate mipmap
    stbi_set_flip_vertically_on_load(true);

    int width, height, nrChannels;
    unsigned char* data = stbi_load("container.jpg", &width, &height, &nrChannels, 0);
    if (data) {
        // create texture with level0-mipmap, RGB format
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else {
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);


    unsigned int texture1;
    glGenTextures(1, &texture1);
    glBindTexture(GL_TEXTURE_2D, texture1);     // all upcoming GL_TEXTURE_2D operations have effect on this object
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // texture filtering
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    data = stbi_load("awesomeface.png", &width, &height, &nrChannels, 0);
    if (data) {
        // create texture with level0-mipmap, RGBA format
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else {
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);
    shader.use();
    shader.setInt("texture0", 0);
    shader.setInt("texture1", 1);

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

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

        // bind texture
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, texture0);
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, texture1);

        // render the triangle
        // shader.use();
        glm::mat4 trans = glm::mat4(1.0f);  // identity matrix
        trans = glm::rotate(trans, glm::radians(45.0f), glm::vec3(0.0f, 0.0f, 1.0f));
        trans = glm::translate(trans, glm::vec3(0.5f, -0.5f, 0.0f));


        shader.setFloat("mixParam", mixParam);
        shader.setMat4("transform", trans);
        glBindVertexArray(VAO);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

        // 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, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);
    // 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_UP) == GLFW_PRESS)
        mixParam += 0.001f;
    if (glfwGetKey(window, GLFW_KEY_DOWN) == GLFW_PRESS)
        mixParam -= 0.001f;
    mixParam = clamp(1.0, 0.0, mixParam);
}

// 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);
}

float clamp(float up, float down, float val) {
    if (val > up) return up;
    if (val < down) return down;
    return val;
}