OpenGL 2. 着色器

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

// 函数声明
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
void checkShaderCompileStatus(unsigned int shader, const std::string& type);
void checkProgramLinkStatus(unsigned int program);

// 着色器源代码
const char* vertexShaderSource = R"(
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
out vec3 ourColor;
void main()
{
    gl_Position = vec4(aPos, 1.0);
    ourColor = aColor;
    gl_PointSize = 20.0f;
}
)";

const char* fragmentShaderSource = R"(
#version 330 core
out vec4 FragColor;
in vec3 ourColor;
void main()
{
    FragColor = vec4(ourColor, 1.0f);
}
)";

int main()
{
    // 初始化 GLFW
    if (!glfwInit()) {
        std::cerr << "Failed to initialize GLFW" << std::endl;
        return -1;
    }

    // 配置 GLFW
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    // 创建窗口
    GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", nullptr, nullptr);
    if (!window) {
        std::cerr << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

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

    // 配置全局 OpenGL 状态
    glViewport(0, 0, 800, 600);
    glEnable(GL_PROGRAM_POINT_SIZE);
    glClearColor(0.1f, 0.1f, 0.1f, 1.0f); // 深灰色背景

    // 定义顶点数据
    float vertices[] = {
        // 位置              // 颜色
         0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f,  // 右下 - 红色
        -0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f,  // 左下 - 绿色
         0.0f,  0.5f, 0.0f, 0.0f, 0.0f, 1.0f   // 顶部 - 蓝色
    };

    // 创建并配置 VAO 和 VBO
    unsigned int VAO, VBO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);

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

    // 位置属性
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    
    // 颜色属性
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    // 解绑 VAO (不是必须的，但良好的习惯)
    glBindVertexArray(0);

    // 创建并编译着色器
    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, nullptr);
    glCompileShader(vertexShader);
    checkShaderCompileStatus(vertexShader, "VERTEX");

    unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, nullptr);
    glCompileShader(fragmentShader);
    checkShaderCompileStatus(fragmentShader, "FRAGMENT");

    // 创建着色器程序并链接
    unsigned int shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);
    checkProgramLinkStatus(shaderProgram);

    // 删除着色器对象 (已链接到程序中，不再需要)
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

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

        // 渲染
        glClear(GL_COLOR_BUFFER_BIT);
        
        // 绘制三角形
        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 3);

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

    // 清理资源
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteProgram(shaderProgram);

    glfwTerminate();
    return 0;
}

// 回调函数定义
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);
}

// 着色器编译错误检查
void checkShaderCompileStatus(unsigned int shader, const std::string& type)
{
    int success;
    char infoLog[512];
    glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
    if (!success) {
        glGetShaderInfoLog(shader, 512, nullptr, infoLog);
        std::cerr << "ERROR::SHADER::" << type << "::COMPILATION_FAILED\n" 
                  << infoLog << std::endl;
    }
}

// 程序链接错误检查
void checkProgramLinkStatus(unsigned int program)
{
    int success;
    char infoLog[512];
    glGetProgramiv(program, GL_LINK_STATUS, &success);
    if (!success) {
        glGetProgramInfoLog(program, 512, nullptr, infoLog);
        std::cerr << "ERROR::PROGRAM::LINKING_FAILED\n" 
                  << infoLog << std::endl;
    }
}

着色器 - LearnOpenGL CN