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发布日期: 2022-08-10

使用glm数学库

数学知识参考3d数学部分 opengl glfwGetTime()时间函数

glm数学库 cpp #include <glm/glm.hpp> #include <glm/gtc/matrix_transform.hpp> #include <glm/gtc/type_ptr.hpp>
矩阵和向量初始化 cpp //矩阵初始化 glm::mat4 mat = glm::mat4(1.0f) //向量初始化 glm::vec4 vec(1.0f, 0.0f, 0.0f, 1.0f);
基础方法
1. 位移 glm::translate
2. 旋转 glm::rotate
3. 缩放 glm::scale
简单示例 使用transform
1. 顶点Shader cpp #version 330 core layout (location = 0) in vec3 aPos; layout (location = 1) in vec2 aTexCoord; out vec2 TexCoord; uniform mat4 transform; //传递tranform矩阵，包含旋转偏移缩放量 void main() { gl_Position = transform * vec4(aPos, 1.0f); TexCoord = vec2(aTexCoord.x, 1.0 - aTexCoord.y); }
2. 传递 transform值给Shader cpp unsigned int transformLoc = glGetUniformLocation(ourShader.ID, "transform"); glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(trans));

完整代码

    #include "glad/glad.h"
    #include "GLFW/glfw3.h"
    //图片库
    #define STB_IMAGE_IMPLEMENTATION
    #include "stb_image.h"
    //glm OpenGL Math库
    #include "glm/glm.hpp"
    #include "glm/gtc/matrix_transform.hpp"
    #include "glm/gtc/type_ptr.hpp"
    #include "shader.h"
    #include <iostream>
    using namespace std;
    const int wWidth = 800, wHeight = 600;
    const char* wName = "LearnOpenGL";
    float vertices[] = {
        //位置                    // 基础颜色          // 题图uv
            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, //  第一个三角形
        1, 2, 3  //  第二个三角形
    };
    void framebuffer_size_callback(GLFWwindow* window, int width, int height)
    {
        glViewport(0, 0, width, height);
    }
    void processInput(GLFWwindow *window)
    {
        if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
            glfwSetWindowShouldClose(window, true);
    }
    int main()
    {
        //1. 初始化
        if (glfwInit() == GLFW_FALSE)
        {
            cout << "init glfw fail";
            return 1;
        }
        //2. 基本设置
        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
        glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    #if __APPLE__
        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE);
    #endif
        //3. 创建窗口
        GLFWwindow *window = glfwCreateWindow(wWidth, wHeight, wName, nullptr, nullptr);
        if (window == nullptr)
        {
            cout << "Failed to create GLFW window";
            goto TERMINATE;
            //return 1;
        }
        //4. 当前主线程上下文窗口
        glfwMakeContextCurrent(window);
        //5. 使用glad管理OpenGL指针。
        if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
        {
            std::cout << "Failed to initialize GLAD" << std::endl;
            goto TERMINATE;
            //return 1;
        }
        //6. 设置视口
        glViewport(0, 0, wWidth, wHeight);
        //7. 设置resize回调，对应刷新视口
        glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
        Shader shader("res/shaders/sample_vertex_transoform.shader", "res/shaders/sample_fragment_transoform.shader");
        unsigned int VBO, VAO, EBO;
        glGenVertexArrays(1, &VAO);
        glBindVertexArray(VAO);
        glGenBuffers(1, &VBO);
        glBindBuffer(GL_ARRAY_BUFFER, VBO);
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
        glGenBuffers(1, &EBO);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
        //1. 指定顶点的顶点属性的结构，顶点 3个float，从0开始，整体每一组数据8个。
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
        glEnableVertexAttribArray(0);
        //2. 指定颜色的顶点属性的结构，三色 3个float，从3开始，整体每一组数据8个。
        glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
        glEnableVertexAttribArray(1);
        //3. 指定uv的顶点属性的结构，uv 2个float，从6开始，整体每一组数据8个。
        glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
        glEnableVertexAttribArray(2);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glBindVertexArray(0);
        unsigned int texture1, texture2;
        //加载贴图1
        glGenTextures(1, &texture1);
        glBindTexture(GL_TEXTURE_2D, texture1);
        // 设置 wrapping 参数
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        // 设置  filtering 参数
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        // 加载解析贴图文件
        int width, height, nrChannels;
        stbi_set_flip_vertically_on_load(true); // tell stb_image.h to flip loaded texture's on the y-axis.
        unsigned char* data = stbi_load("./res/textures/container.jpg", &width, &height, &nrChannels, 0);
        if (data)
        {
            //第一个 GL_RGB 将被转换的格式， 第二个GL_RGB原始文件的格式， 格式不匹配会报错。
            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);
        //加载贴图2
        glGenTextures(1, &texture2);
        glBindTexture(GL_TEXTURE_2D, texture2);
        //  设置 wrapping 参数
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        // 设置  filtering 参数
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        // l加载解析贴图文件
        data = stbi_load("./res/textures/awesomeface.png", &width, &height, &nrChannels, 0);
        if (data)
        {
            //第一个 GL_RGB 将被转换的格式， 第二个GL_RGB原始文件的格式， 格式不匹配会报错。
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 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);
        //指定采样器贴图储存的位置
        shader.use();
        shader.setInt("texture1", 0);
        shader.setInt("texture2", 1);
        while (!glfwWindowShouldClose(window))
        {
            processInput(window);
            glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
            glClear(GL_COLOR_BUFFER_BIT);
            // bind Texture1
            glActiveTexture(GL_TEXTURE0);
            glBindTexture(GL_TEXTURE_2D, texture1);
            // bind Texture2
            glActiveTexture(GL_TEXTURE1);
            glBindTexture(GL_TEXTURE_2D, texture2);
            glm::mat4 transform = glm::mat4(1.0f); 
            transform = glm::translate(transform, glm::vec3(0.5f, -0.5f, 0.0f));
            transform = glm::rotate(transform, (float)glfwGetTime(), glm::vec3(0.0f, 0.0f, 1.0f));
            shader.use();
            unsigned int transformLoc = glGetUniformLocation(shader.ID, "transform");
            glUniformMatrix4fv(transformLoc, (float)glfwGetTime(), GL_FALSE, glm::value_ptr(transform));
            glBindVertexArray(VAO);
            glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
            glfwSwapBuffers(window);
            glfwPollEvents();
        }
        glDeleteVertexArrays(1, &VAO);
        glDeleteBuffers(1, &VBO);
        glDeleteBuffers(1, &EBO);
    TERMINATE:
        glfwTerminate();
        return 0;
    }

Yonggang Long

https://one2world.github.io/2022/08/10/opengl/01-ji-chu-bu-fen/5.shi-yong-glm-shu-xue-ku/

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2022-08-10 Yonggang Long

使用glm数学库

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