计算机图形学入门（七）-着色（着色频率、图形管线、纹理映射）代码

这里提供一个简单的OpenGL代码示例，演示如何进行着色、纹理映射等基本图形渲染操作。

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

// 窗口大小
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

// 顶点着色器代码
const char *vertexShaderSource = "#version 330 core\n"
    "layout (location = 0) in vec3 aPos;\n"
    "layout (location = 1) in vec3 aColor;\n"
    "layout (location = 2) in vec2 aTexCoord;\n"
    "out vec3 ourColor;\n"
    "out vec2 TexCoord;\n"
    "void main()\n"
    "{\n"
    "   gl_Position = vec4(aPos, 1.0);\n"
    "   ourColor = aColor;\n"
    "   TexCoord = vec2(aTexCoord.x, aTexCoord.y);\n"
    "}\0";

// 片段着色器代码
const char *fragmentShaderSource = "#version 330 core\n"
    "out vec4 FragColor;\n"
    "in vec3 ourColor;\n"
    "in vec2 TexCoord;\n"
    "uniform sampler2D ourTexture;\n"
    "void main()\n"
    "{\n"
    "   FragColor = texture(ourTexture, TexCoord) * vec4(ourColor, 1.0f);\n"
    "}\n\0";

int main()
{
    // 初始化GLFW
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    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);

    // 初始化GLAD
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // 编译顶点着色器
    int success;
    char infoLog[512];
    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }

    // 编译片段着色器
    unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    }

    // 创建着色器程序
    unsigned int shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);
    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
    if (!success)
    {
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    // 设置顶点数据
    float vertices[] = {
        // 位置              // 颜色              // 纹理坐标
         0.5f,  0.5f, 0.0f,  1.0f, 0.0f, 0.0f,   1.0f, 1.0f, // 右上角
         0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,   1.0f, 0.0f, // 右下角
        -0.5f, -0.5f, 0.0f,  0.0f, 0.0f, 1.0f,   0.0f, 0.0f, // 左下角
        -0.5f,  0.5f, 0.0f,  1.0f, 1.0f, 0.0f,   0.0f, 1.0f  // 左上角
    };
    unsigned int indices[] = {
        0, 1, 3, // 第一个三角形
        1, 2, 3  // 第二个三角形
    };
    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);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);

    // 创建纹理
    unsigned int texture;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    // 设置纹理参数
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    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);
    unsigned char *data = stbi_load("container.jpg", &width, &height, &nrChannels, 0);
    if (data)
    {
        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);

    // 渲染循环
    while (!glfwWindowShouldClose(window))
    {
        // 输入处理
        processInput(window);

        // 渲染指令
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        // 绑定纹理
        glBindTexture(GL_TEXTURE_2D, texture);

        // 设置uniform
        glUseProgram(shaderProgram);
        int textureLocation = glGetUniformLocation(shaderProgram, "ourTexture");
        glUniform1i(textureLocation, 0);

        // 绘制矩形
        glBindVertexArray(VAO);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

        // 交换缓冲区和轮询IO事件
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // 释放资源
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);
    glfwTerminate();
    return 0;
}

void processInput(GLFWwindow *window)
{
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

这段代码实现了一个简单的矩形渲染，并将颜色和纹理信息传递到顶点和片段着色器中进行处理。在渲染循环中，先绑定纹理，设置uniform，然后绘制矩形。注意，这里使用了stb_image库来加载纹理图片。