myStack.cpp

#include <glew.h>
#include <glfw3.h>
#include <string>
#include <iostream>
#include <fstream>
#include <cmath>
#include <stack>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp> // glm::value_ptr
#include <glm/gtc/matrix_transform.hpp> // glm::translate, glm::rotate, glm::scale, glm::perspective
#include "Utils.h"
using namespace std;

#define numVAOs 1
#define numVBOs 2

float cameraX, cameraY, cameraZ;
GLuint renderingProgram;
GLuint vao[numVAOs];
GLuint vbo[numVBOs];

// variable allocation for display
GLuint mvLoc, projLoc;
int width, height;
float aspect;
glm::mat4 pMat, vMat, mMat, mvMat;

/**
 * mvStack
 * push()：在堆栈顶部创建一个新的条目。我们通常会把目前在堆栈顶部的矩阵复制一份，并和其他的变换结合，然后再利用这个命令把新的矩阵副本推入堆栈中。
 * pop()：移除（并返回）最顶部的矩阵。
 * top()：在不移除的情况下，返回堆栈最顶部矩阵的引用。
 * <stack>.top() *= rotate（构建旋转矩阵的参数）。
 * <stack>.top() *= scale（构建缩放矩阵的参数）。　　←---　直接对堆栈顶部的矩阵应用变换。
 * <stack>.top() *= translate（构建平移矩阵的参数）。　　←---　直接对堆栈顶部的矩阵应用变换。
 */
stack<glm::mat4> mvStack;

void setupVertices(void) {
    float vertexPositions[108] =
            { -1.0f,  1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f,
              1.0f, -1.0f, -1.0f, 1.0f,  1.0f, -1.0f, -1.0f,  1.0f, -1.0f,
              1.0f, -1.0f, -1.0f, 1.0f, -1.0f,  1.0f, 1.0f,  1.0f, -1.0f,
              1.0f, -1.0f,  1.0f, 1.0f,  1.0f,  1.0f, 1.0f,  1.0f, -1.0f,
              1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f, 1.0f,  1.0f,  1.0f,
              -1.0f, -1.0f,  1.0f, -1.0f,  1.0f,  1.0f, 1.0f,  1.0f,  1.0f,
              -1.0f, -1.0f,  1.0f, -1.0f, -1.0f, -1.0f, -1.0f,  1.0f,  1.0f,
              -1.0f, -1.0f, -1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f,  1.0f,
              -1.0f, -1.0f,  1.0f,  1.0f, -1.0f,  1.0f,  1.0f, -1.0f, -1.0f,
              1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f,  1.0f,
              -1.0f,  1.0f, -1.0f, 1.0f,  1.0f, -1.0f, 1.0f,  1.0f,  1.0f,
              1.0f,  1.0f,  1.0f, -1.0f,  1.0f,  1.0f, -1.0f,  1.0f, -1.0f
            };
    float pyramidPositions[54] =
            { -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 0.0f, 1.0f, 0.0f,    //front
              1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 0.0f, 1.0f, 0.0f,    //right
              1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 0.0f, 1.0f, 0.0f,  //back
              -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, 0.0f, 1.0f, 0.0f,  //left
              -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, //LF
              1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f  //RR
            };
    glGenVertexArrays(1, vao);
    glBindVertexArray(vao[0]);
    glGenBuffers(numVBOs, vbo);

    glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexPositions), vertexPositions, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
    glBufferData(GL_ARRAY_BUFFER, sizeof(pyramidPositions), pyramidPositions, GL_STATIC_DRAW);
}

void init(GLFWwindow* window) {
    cout << "init window" << endl;
    renderingProgram = Utils::createShaderProgram(
            "/Users/apple/Desktop/vscode/gl/glsl/4-4/vertShader.glsl",
            "/Users/apple/Desktop/vscode/gl/glsl/4-4/fragShader.glsl"
            );

    glfwGetFramebufferSize(window, &width, &height);
    aspect = (float)width / (float)height;
    pMat = glm::perspective(1.0472f, aspect, 0.1f, 1000.0f);

    cameraX = 0.0f; cameraY = 0.0f; cameraZ = 12.0f;
    setupVertices();
}
/**
 * 配置
    •　实例化矩阵堆栈
    摄像机
    •　将新矩阵推入堆栈（这将实例化一个空的视图矩阵）
    •　将变换应用于堆栈顶部的视图矩阵
    父对象
    •　将新矩阵推入堆栈（这将是父MV矩阵——对第一个父对象来说，它直接复制一份视图矩阵）
    •　应用变换，将父对象的模型矩阵和复制的视图矩阵结合
    •　发送最顶层的矩阵（即对顶点着色器中的MV矩阵统一变量使用"glm::value_ptr()"）
    •　绘制父对象
    子对象
    •　将新矩阵推入堆栈。这将是子对象的MV矩阵，最初直接复制一份父对象的MV矩阵
    •　应用变换，将子对象的模型矩阵和复制的父MV矩阵结合
    •　发送最顶层的矩阵（即对顶点着色器中的MV矩阵统一变量使用"glm:: value_ptr()"）
    •　绘制子对象
    清理
    •　将新矩阵推入堆栈。这将是子对象的MV矩阵，最初直接复制一份父对象的MV矩阵
    •　应用变换，将子对象的模型矩阵和复制的父MV矩阵结合
    •　发送最顶层的矩阵（即对顶点着色器中的MV矩阵统一变量使用"glm:: value_ptr()"）
    •　绘制子对象
 * @param window
 * @param currentTime
 */
void display(GLFWwindow* window, double currentTime) {
    glClear(GL_DEPTH_BUFFER_BIT);
    glClearColor(0.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);

    glUseProgram(renderingProgram);

    mvLoc = glGetUniformLocation(renderingProgram, "mv_matrix");
    projLoc = glGetUniformLocation(renderingProgram, "proj_matrix");

    vMat = glm::translate(glm::mat4(1.0f), glm::vec3(-cameraX, -cameraY, -cameraZ));
    mvStack.push(vMat);

    glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(pMat));

    // ----------------------  pyramid == sun
    mvStack.push(mvStack.top());
    mvStack.top() *= glm::translate(glm::mat4(1.0f), glm::vec3(0.0f, 0.0f, 0.0f));
    mvStack.push(mvStack.top());
    mvStack.top() *= rotate(glm::mat4(1.0f), (float)currentTime, glm::vec3(1.0, 0.0, 0.0));
    glUniformMatrix4fv(mvLoc, 1, GL_FALSE, glm::value_ptr(mvStack.top()));
    glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
    glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
    glEnableVertexAttribArray(0);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glDrawArrays(GL_TRIANGLES, 0, 18);
    mvStack.pop();

    //-----------------------  cube == planet
    mvStack.push(mvStack.top());
    mvStack.top() *= glm::translate(glm::mat4(1.0f), glm::vec3(sin((float)currentTime)*4.0, 0.0f, cos((float)currentTime)*4.0));
    mvStack.push(mvStack.top());
    mvStack.top() *= rotate(glm::mat4(1.0f), (float)currentTime, glm::vec3(0.0, 1.0, 0.0));
    glUniformMatrix4fv(mvLoc, 1, GL_FALSE, glm::value_ptr(mvStack.top()));
    glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
    glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
    glEnableVertexAttribArray(0);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glDrawArrays(GL_TRIANGLES, 0, 36);
    mvStack.pop();

    //-----------------------  smaller cube == moon
    mvStack.push(mvStack.top());
    mvStack.top() *= glm::translate(glm::mat4(1.0f), glm::vec3(0.0f, sin((float)currentTime)*2.0, cos((float)currentTime)*2.0));
    mvStack.top() *= rotate(glm::mat4(1.0f), (float)currentTime, glm::vec3(0.0, 0.0, 1.0));
    mvStack.top() *= scale(glm::mat4(1.0f), glm::vec3(0.25f, 0.25f, 0.25f));
    glUniformMatrix4fv(mvLoc, 1, GL_FALSE, glm::value_ptr(mvStack.top()));
    glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
    glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
    glEnableVertexAttribArray(0);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glDrawArrays(GL_TRIANGLES, 0, 36);
    mvStack.pop(); mvStack.pop(); mvStack.pop();
    mvStack.pop();  // the final pop is for the view matrix
}

void window_size_callback(GLFWwindow* win, int newWidth, int newHeight) {
    aspect = (float)newWidth / (float)newHeight;
    glViewport(0, 0, newWidth, newHeight);
    pMat = glm::perspective(1.0472f, aspect, 0.1f, 1000.0f);
}

int main(void) {
    GLFWwindow *window;
    if (!glfwInit()) { exit(EXIT_FAILURE); }
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    window = glfwCreateWindow(600, 600, "Chapter 4 - program 4", NULL, NULL);
    #ifdef __APPLE__
        cout << "I'm apple machine" << endl;
        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    #endif
    glfwMakeContextCurrent(window);
    if (glewInit() != GLEW_OK) { exit(EXIT_FAILURE); }
    glfwSwapInterval(1);

    glfwSetWindowSizeCallback(window, window_size_callback);

    init(window);

    while (!glfwWindowShouldClose(window)) {
        display(window, glfwGetTime());
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwDestroyWindow(window);
    glfwTerminate();
    exit(EXIT_SUCCESS);
}