OpenGL 3D旋转的木箱

学习自：

https://learnopengl-cn.github.io/01%20Getting%20started/08%20Coordinate%20Systems/#3d

0，首先添加glm库文件

相关方法可以参照我指定的那篇随便

1，顶点着色器shader.vs

#version  core
layout (location = ) in vec3 aPos;
layout (location = ) in vec2 aTexCoord;

out vec2 TexCoord;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
    gl_Position = projection * view * model * vec4(aPos, 1.0f);
    TexCoord = vec2(aTexCoord.x, aTexCoord.y);
}

2，片段着色器shader.fs

#version  core
out vec4 FragColor;

in vec2 TexCoord;

// texture samplers
uniform sampler2D texture1;
uniform sampler2D texture2;

void main()
{
    // linearly interpolate between both textures (80% container, 20% awesomeface)
    FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 0.2);
}

3，主程序

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

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

 #include "stb_image.h"
 #include "shader_s.h"
 #include <iostream>

 void framebuffer_size_callback(GLFWwindow* window, int width, int height);
 void processInput(GLFWwindow *window);

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

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

 #ifdef __APPLE__
     glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
 #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 -;
     }
     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 -;
     }

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

     // build and compile our shader zprogram
     // ------------------------------------
     Shader ourShader("../res/textures/texture.vs", "../res/textures/texture.fs");

     // set up vertex data (and buffer(s)) and configure vertex attributes
     // ------------------------------------------------------------------
     /*
     float vertices[] = {
         // 位置信息          // 颜色信息           // 纹理 coords
          0.5f,  0.5f, 0.0f,   1.0f, 0.0f, 0.0f,   1.0f, 1.0f, // 右上
          0.5f, -0.5f, 0.0f,   0.0f, 1.0f, 0.0f,   1.0f, 0.0f, // 右下
         -0.5f, -0.5f, 0.0f,   0.0f, 0.0f, 1.0f,   0.0f, 0.0f, // 左下
         -0.5f,  0.5f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f  // 左上
     };
     unsigned int indices[] = {
         0, 1, 3, // 第一个三角形
         1, 2, 3  // 第二个三角形
     };
     */
     float vertices[] = {
     -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
     };

     unsigned int VBO, VAO;
     glGenVertexArrays(, &VAO);
     glGenBuffers(, &VBO);

     glBindVertexArray(VAO);

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

     // position attribute
     glVertexAttribPointer(, , GL_FLOAT, GL_FALSE,  * sizeof(float), (void*));
     glEnableVertexAttribArray();
     // texture coord attribute
     glVertexAttribPointer(, , GL_FLOAT, GL_FALSE,  * sizeof(float), (void*)( * sizeof(float)));
     glEnableVertexAttribArray();

     //    加载并创建纹理
     // -------------------------
     unsigned int texture1, texture2;
     //    第一张纹理

     glGenTextures(, &texture1);
     glBindTexture(GL_TEXTURE_2D, texture1);
     //    为当前绑定的纹理对象设置环绕、过滤方式
     //    将纹理包装设置为GL_REPEAT（默认包装方法）
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
     //    设置纹理过滤参数
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     // 加载并生成纹理
     int width, height, nrChannels;
     stbi_set_flip_vertically_on_load(true); //告诉stb_image.h在y轴上翻转加载的纹理。

     unsigned char *data = stbi_load("../res/textures/container.jpg", &width, &height, &nrChannels, );
     if (data)
     {
         glTexImage2D(GL_TEXTURE_2D, , GL_RGB, width, height, , GL_RGB, GL_UNSIGNED_BYTE, data);
         glGenerateMipmap(GL_TEXTURE_2D);
     }
     else
     {
         std::cout << "Failed to load texture" << std::endl;
     }
     stbi_image_free(data);

     // texture 2
     glGenTextures(, &texture2);
     glBindTexture(GL_TEXTURE_2D, texture2);
     // set the texture wrapping parameters
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);    // set texture wrapping to GL_REPEAT (default wrapping method)
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
     // set texture filtering parameters
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     // load image, create texture and generate mipmaps
     data = stbi_load("../res/textures/awesomeface.png", &width, &height, &nrChannels, );
     if (data)
     {
         //请注意，awesomeface.png具有透明度，因此具有alpha通道，
         //因此请务必告诉OpenGL数据类型为GL_RGBA
         glTexImage2D(GL_TEXTURE_2D, , GL_RGBA, width, height, , GL_RGBA, GL_UNSIGNED_BYTE, data);
         glGenerateMipmap(GL_TEXTURE_2D);
     }
     else
     {
         std::cout << "Failed to load texture" << std::endl;
     }
     stbi_image_free(data);

     //告诉每个采样器的opengl它属于哪个纹理单元（只需要做一次）
     ourShader.use(); //激活着色器
     // either set it manually like so:
     glUniform1i(glGetUniformLocation(ourShader.ID, "texture1"), );
     // or set it via the texture class
     ourShader.setInt("texture2", );

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

         // render
         // ------
         glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // also clear the depth buffer now!

         // bind textures on corresponding texture units
         glActiveTexture(GL_TEXTURE0);
         glBindTexture(GL_TEXTURE_2D, texture1);
         glActiveTexture(GL_TEXTURE1);
         glBindTexture(GL_TEXTURE_2D, texture2);

         // activate shader
         ourShader.use();

         // create transformations
         glm::mat4 model = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
         glm::mat4 view = glm::mat4(1.0f);
         glm::mat4 projection = glm::mat4(1.0f);
         model = glm::rotate(model, (float)glfwGetTime(), glm::vec3(0.5f, 1.0f, 0.0f));
         view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
         projection = glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
         // retrieve the matrix uniform locations
         unsigned int modelLoc = glGetUniformLocation(ourShader.ID, "model");
         unsigned int viewLoc = glGetUniformLocation(ourShader.ID, "view");
         // pass them to the shaders (3 different ways)
         glUniformMatrix4fv(modelLoc, , GL_FALSE, glm::value_ptr(model));
         glUniformMatrix4fv(viewLoc, , GL_FALSE, &view[][]);
         // note: currently we set the projection matrix each frame, but since the projection matrix rarely changes it's often best practice to set it outside the main loop only once.
         ourShader.setMat4("projection", projection);

         // render box
         glBindVertexArray(VAO);
         glDrawArrays(GL_TRIANGLES, , );

         // 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(, &VAO);
     glDeleteBuffers(, &VBO);
     //glDeleteBuffers(1, &EBO);

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

 // 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);
 }

 // 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(, , width, height);
 }

TestShader.cpp

注意一点的是，我们的着色器类，在这里要添加几个方法，我去百度了一下，找到了常用的一些方法，把各个类型的的set函数都加进来了。

 #include "shader_s.h"

 Shader::Shader(const GLchar * vertexPath, const GLchar * fragmentPath)
 {
     // 1. 从文件路径中获取顶点/片段着色器
     std::string vertexCode;
     std::string fragmentCode;
     std::ifstream vShaderFile;
     std::ifstream fShaderFile;
     // 保证ifstream对象可以抛出异常：
     vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
     fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
     try
     {
         // 打开文件
         vShaderFile.open(vertexPath);
         fShaderFile.open(fragmentPath);
         std::stringstream vShaderStream, fShaderStream;
         // 读取文件的缓冲内容到数据流中
         vShaderStream << vShaderFile.rdbuf();
         fShaderStream << fShaderFile.rdbuf();
         // 关闭文件处理器
         vShaderFile.close();
         fShaderFile.close();
         // 转换数据流到string
         vertexCode = vShaderStream.str();
         fragmentCode = fShaderStream.str();
     }
     catch (std::ifstream::failure e)
     {
         std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
     }
     const char* vShaderCode = vertexCode.c_str();
     const char * fShaderCode = fragmentCode.c_str();
     // 2. 编译着色器
     unsigned int vertex, fragment;
     // 顶点着色器    vs
     vertex = glCreateShader(GL_VERTEX_SHADER);
     glShaderSource(vertex, , &vShaderCode, NULL);
     glCompileShader(vertex);
     checkCompileErrors(vertex, "VERTEX");
     // 片段着色器    fs
     fragment = glCreateShader(GL_FRAGMENT_SHADER);
     glShaderSource(fragment, , &fShaderCode, NULL);
     glCompileShader(fragment);
     checkCompileErrors(fragment, "FRAGMENT");
     // 着色器程序
     ID = glCreateProgram();
     glAttachShader(ID, vertex);
     glAttachShader(ID, fragment);
     glLinkProgram(ID);
     checkCompileErrors(ID, "PROGRAM");
     // 删除着色器，它们已经链接到我们的程序中了，已经不再需要了    glDeleteShader(vertex);
     glDeleteShader(fragment);
 }

 void Shader::use()
 {
     glUseProgram(ID);
 }

 void Shader::setBool(const std::string & name, bool value) const
 {
     glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
 }

 void Shader::setInt(const std::string & name, int value) const
 {
     glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
 }

 void Shader::setFloat(const std::string & name, float value) const
 {
     glUniform1f(glGetUniformLocation(ID, name.c_str()), value);
 }

 void Shader::setVec2(const std::string & name, const glm::vec2 & value) const
 {
     glUniform2fv(glGetUniformLocation(ID, name.c_str()), , &value[]);
 }

 void Shader::setVec2(const std::string & name, float x, float y) const
 {
     glUniform2f(glGetUniformLocation(ID, name.c_str()), x, y);
 }

 void Shader::setVec3(const std::string & name, const glm::vec3 & value) const
 {
     glUniform3fv(glGetUniformLocation(ID, name.c_str()), , &value[]);
 }

 void Shader::setVec3(const std::string & name, float x, float y, float z) const
 {
     glUniform3f(glGetUniformLocation(ID, name.c_str()), x, y, z);
 }

 void Shader::setVec4(const std::string & name, const glm::vec4 & value) const
 {
     glUniform4fv(glGetUniformLocation(ID, name.c_str()), , &value[]);
 }

 void Shader::setVec4(const std::string & name, float x, float y, float z, float w)
 {
     glUniform4f(glGetUniformLocation(ID, name.c_str()), x, y, z, w);
 }

 void Shader::setMat2(const std::string & name, const glm::mat2 & mat) const
 {
     glUniformMatrix2fv(glGetUniformLocation(ID, name.c_str()), , GL_FALSE, &mat[][]);
 }

 void Shader::setMat3(const std::string & name, const glm::mat3 & mat) const
 {
     glUniformMatrix3fv(glGetUniformLocation(ID, name.c_str()), , GL_FALSE, &mat[][]);
 }

 void Shader::setMat4(const std::string & name, const glm::mat4 & mat) const
 {
     glUniformMatrix4fv(glGetUniformLocation(ID, name.c_str()), , GL_FALSE, &mat[][]);
 }

 void Shader::checkCompileErrors(unsigned int shader, std::string type)
 {
     int success;
     char infoLog[];
     if (type != "PROGRAM")
     {
         glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
         if (!success)
         {
             glGetShaderInfoLog(shader, , NULL, infoLog);
             std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
         }
     }
     else
     {
         glGetProgramiv(shader, GL_LINK_STATUS, &success);
         if (!success)
         {
             glGetProgramInfoLog(shader, , NULL, infoLog);
             std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
         }
     }
 }

shader_s.cpp

自己把相关的类定义写道头文件中就可以了。

4，运行结果