17blending_discard.cpp

#define STB_IMAGE_IMPLEMENTATION
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <glad/glad.h> 
#include <GLFW/glfw3.h>

#include "shader_m.h"
#include "camera.h"
#include "model.h"

#include<iostream>
#include <glm/gtx/string_cast.hpp>
using namespace std;


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

unsigned int loadTexture(char const* path);
// 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);
//glm::vec3 lightDirection(0.2f, 1.0f, 0.3f);
void framebuffer_size_callback(GLFWwindow* window, int width, int height);//屏幕缩放事件
void mouse_callback(GLFWwindow* window, double xpos, double ypos);//鼠标移动事件
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);//滚轮事件
void processInput(GLFWwindow* window);//按键输入事件
void mouse_callback(GLFWwindow* window, double xposIn, double yposIn)
{
    float xpos = static_cast<float>(xposIn);
    float ypos = static_cast<float>(yposIn);

    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);
}
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
    camera.ProcessMouseScroll(static_cast<float>(yoffset));
}
/*
使用GLFW的glfwGetKey函数，它需要一个窗口以及一个按键作为输入。
这个函数将会返回这个按键是否正在被按下。
我们将创建一个processInput函数来让所有的输入代码保持整洁
返回键(Esc)（如果没有按下，glfwGetKey将会返回GLFW_RELEASE。
如果用户的确按下了返回键，我们将通过glfwSetwindowShouldClose使用把WindowShouldClose属性设置为 true的方法关闭GLFW。
下一次while循环的条件检测将会失败，程序将会关闭。
*/
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);
}
//当用户改变窗口的大小的时候，视口也应该被调整。我们可以对窗口注册一个回调函数(Callback Function)，
//它会在每次窗口大小被调整的时候被调用。这个回调函数的原型如下
//需要一个GLFWwindow作为它的第一个参数，以及两个整数表示窗口的新维度。每当窗口改变大小，
//GLFW会调用这个函数并填充相应的参数供你处理。
//还需要注册这个函数，告诉GLFW我们希望每当窗口调整大小的时候调用这个函数：
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    glViewport(0, 0, width, height);
}

int main()
{


    glfwInit();//初始化glfw
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    //glfwWindowHint函数的第一个参数代表选项的名称，我们可以从很多以GLFW_开头的枚举值中选择；
    //第二个参数接受一个整型，用来设置这个选项的值
    // GLFW_CONTEXT_VERSION_MAJOR表示所选客户端 API 的任何有效主版本号（OpenGL的版本为3.3 所以主版本号 为3）
    //该函数的所有的选项以及对应的值都可以在 GLFW’s window handling(https://www.glfw.org/docs/latest/window.html#window_hints) 这篇文档中找到
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    // GLFW_CONTEXT_VERSION_MINOR表示所选客户端 API 的任何有效次版本号（OpenGL的版本为3.3 所以次版本号 为3）
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    //GLFW_OPENGL_PROFILE表示上下文使用的 OpenGL 配置文件,值为GLFW_OPENGL_CORE_PROFILE，即告诉GLFW我们使用的是核心模式(Core-profile)
    //glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);//如果使用的是Mac OS X系统，你还需要加这行代码到你的初始化代码中这些配置才能起作用

    GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);//通知GLFW将我们窗口的上下文设置为当前线程的主上下文了
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);//注册回调函数
    glfwSetCursorPosCallback(window, mouse_callback);//注册回调函数
    glfwSetScrollCallback(window, scroll_callback);//注册回调函数
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);//告诉GLFW捕获我们的鼠标
    //GLAD是用来管理OpenGL的函数指针的，
    //所以在调用任何OpenGL的函数之前我们需要初始化GLAD
    //给GLAD传入了用来加载系统相关的OpenGL函数指针地址的函数。GLFW给我们的是glfwGetProcAddress
    //，它根据我们编译的系统定义了正确的函数
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    //OpenGL渲染窗口的尺寸大小，即视口(Viewport)
    //glViewport函数前两个参数控制窗口左下角的位置。第三个和第四个参数控制渲染窗口的宽度和高度
    //际上也可以将视口的维度设置为比GLFW的维度小，这样子之后所有的OpenGL渲染将会在一个更小的窗口中显示，
    //这样子的话我们也可以将一些其它元素显示在OpenGL视口之外
    //OpenGL坐标范围只为-1到1，将(-1到1)范围内的坐标映射到(0, 800)和(0, 600)
    glViewport(0, 0, 800, 600);

    //窗口被第一次显示的时候framebuffer_size_callback也会被调用。
    //对于视网膜(Retina)显示屏，width和height都会明显比原输入值更高一点
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

    // 告诉stb_image.h在y轴上翻转加载的纹理(在加载模型之前)。
    stbi_set_flip_vertically_on_load(true);

    //配置全局OpenGL状态
    glEnable(GL_DEPTH_TEST);//开启深度测试
    //glDepthFunc(GL_ALWAYS);//总是通过深度测试，功能与glDisable(GL_DEPTH_TEST);一样

    Shader shader("17.blending.vs", "17.blending.fs");//用于绘制边框

    float cubeVertices[] = {
        // positions          // texture Coords
        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
         0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,

        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
        -0.5f,  0.5f,  0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,

        -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
         0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
         0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
         0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
         0.5f, -0.5f, -0.5f,  1.0f, 1.0f,
         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
         0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,

        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
         0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
         0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f
    };
    float planeVertices[] = {
        // positions          // texture Coords (note we set these higher than 1 (together with GL_REPEAT as texture wrapping mode). this will cause the floor texture to repeat)
         5.0f, -0.5f,  5.0f,  2.0f, 0.0f,
        -5.0f, -0.5f,  5.0f,  0.0f, 0.0f,
        -5.0f, -0.5f, -5.0f,  0.0f, 2.0f,

         5.0f, -0.5f,  5.0f,  2.0f, 0.0f,
        -5.0f, -0.5f, -5.0f,  0.0f, 2.0f,
         5.0f, -0.5f, -5.0f,  2.0f, 2.0f
    };
    float transparentVertices[] = {
        // positions         
        0.0f,  -0.5f,  0.0f,  0.0f,  0.0f,
        0.0f, 0.5f,  0.0f,  0.0f,  1.0f,
        1.0f, 0.5f,  0.0f,  1.0f,  1.0f,

        0.0f,  -0.5f,  0.0f,  0.0f,  0.0f,
        1.0f, 0.5f,  0.0f,  1.0f,  1.0f,
        1.0f,  -0.5f,  0.0f,  1.0f,  0.0f
    };

    unsigned int cubeVAO, cubeVBO;
    glGenVertexArrays(1, &cubeVAO);
    glGenBuffers(1, &cubeVBO);
    glBindVertexArray(cubeVAO);
    glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(cubeVertices), &cubeVertices, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
    glBindVertexArray(0);



    unsigned int planeVAO, planeVBO;
    glGenVertexArrays(1, &planeVAO);
    glGenBuffers(1, &planeVBO);
    glBindVertexArray(planeVAO);
    glBindBuffer(GL_ARRAY_BUFFER, planeVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(planeVertices), &planeVertices, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
    glBindVertexArray(0);


    unsigned int transparentVAO, transparentVBO;
    glGenVertexArrays(1, &transparentVAO);
    glGenBuffers(1, &transparentVBO);
    glBindVertexArray(transparentVAO);
    glBindBuffer(GL_ARRAY_BUFFER, transparentVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(transparentVertices), transparentVertices, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
    glBindVertexArray(0);

    unsigned int cubeTexture = loadTexture("marble.jpg");
    unsigned int floorTexture = loadTexture("metal.png");
    unsigned int transparentTexture = loadTexture("window.png");

    vector<glm::vec3> windows
    {
        glm::vec3(-1.5f, 0.0f, -0.48f),
        glm::vec3(1.5f, 0.0f, 0.51f),
        glm::vec3(0.0f, 0.0f, 0.7f),
        glm::vec3(-0.3f, 0.0f, -2.3f),
        glm::vec3(0.5f, 0.0f, -0.6f)
    };

    shader.use();
    shader.setInt("texture1", 0);

    while (!glfwWindowShouldClose(window))
    {

        //输入
        processInput(window);//循环时监控是否按下键
        //渲染
        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);//设置屏幕颜色
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //颜色清空屏幕|清楚深度缓冲|清除模板缓冲
        //glActiveTexture(GL_TEXTURE0);
        //glBindTexture(GL_TEXTURE_2D, texture);
        //glActiveTexture(GL_TEXTURE1);
        //glBindTexture(GL_TEXTURE_2D, texture1);
        float currentFrame = static_cast<float>(glfwGetTime());
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;
        //对窗户远近进行排序。渲染时从远向近渲染
        std::map<float, glm::vec3> sorted;
        for (unsigned int i = 0; i < windows.size(); i++)
        {
            float distance = glm::length(camera.Position - windows[i]);
            sorted[distance] = windows[i];
        }

        // draw objects
        shader.use();
        glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
        glm::mat4 view = camera.GetViewMatrix();
        glm::mat4 model = glm::mat4(1.0f);
        shader.setMat4("projection", projection);
        shader.setMat4("view", view);
        // cubes
        glBindVertexArray(cubeVAO);
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, cubeTexture);
        model = glm::translate(model, glm::vec3(-1.0f, 0.0f, -1.0f));
        shader.setMat4("model", model);
        glDrawArrays(GL_TRIANGLES, 0, 36);
        model = glm::mat4(1.0f);
        model = glm::translate(model, glm::vec3(2.0f, 0.0f, 0.0f));
        shader.setMat4("model", model);
        glDrawArrays(GL_TRIANGLES, 0, 36);
        // floor
        glBindVertexArray(planeVAO);
        glBindTexture(GL_TEXTURE_2D, floorTexture);
        model = glm::mat4(1.0f);
        shader.setMat4("model", model);
        glDrawArrays(GL_TRIANGLES, 0, 6);
        // vegetation
        glBindVertexArray(transparentVAO);
        glBindTexture(GL_TEXTURE_2D, transparentTexture);
        for (std::map<float, glm::vec3>::reverse_iterator it = sorted.rbegin(); it != sorted.rend(); ++it)
        {
            model = glm::mat4(1.0f);
            model = glm::translate(model, it->second);
            shader.setMat4("model", model);
            glDrawArrays(GL_TRIANGLES, 0, 6);
        }



        glfwSwapBuffers(window);
        glfwPollEvents();
    }
    //渲染循环后释放所有资源
    glDeleteVertexArrays(1, &cubeVAO);
    glDeleteVertexArrays(1, &planeVAO);
    glDeleteBuffers(1, &cubeVBO);
    glDeleteBuffers(1, &planeVBO);

    glfwTerminate();
    return 0;
}
unsigned int loadTexture(char const* path)
{
    unsigned int textureID;
    glGenTextures(1, &textureID);

    int width, height, nrComponents;
    unsigned char* data = stbi_load(path, &width, &height, &nrComponents, 0);
    if (data)
    {
        GLenum format;
        if (nrComponents == 1)
            format = GL_RED;
        else if (nrComponents == 3)
            format = GL_RGB;
        else if (nrComponents == 4)
            format = GL_RGBA;

        glBindTexture(GL_TEXTURE_2D, textureID);
        glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, format == GL_RGBA ? GL_CLAMP_TO_EDGE : GL_REPEAT); // for this tutorial: use GL_CLAMP_TO_EDGE to prevent semi-transparent borders. Due to interpolation it takes texels from next repeat 
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, format == GL_RGBA ? GL_CLAMP_TO_EDGE : GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

        stbi_image_free(data);
    }
    else
    {
        std::cout << "Texture failed to load at path: " << path << std::endl;
        stbi_image_free(data);
    }

    return textureID;
}