glClearColor和混合

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>

void init() {
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f); // 设置清除颜色为深蓝色
    glEnable(GL_BLEND); // 启用混合
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); // 设置混合函数
}

void render() {
    glClear(GL_COLOR_BUFFER_BIT); // 清除颜色缓冲区

    // 绘制一个半透明的红色矩形
    glColor4f(1.0f, 0.0f, 0.0f, 0.5f);
    glBegin(GL_QUADS);
        glVertex2f(-0.5f, -0.5f);
        glVertex2f(0.5f, -0.5f);
        glVertex2f(0.5f, 0.5f);
        glVertex2f(-0.5f, 0.5f);
    glEnd();
}

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

    GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGL Example", nullptr, nullptr);
    if (!window) {
        std::cerr << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);
    glewExperimental = true;
    if (glewInit() != GLEW_OK) {
        std::cerr << "Failed to initialize GLEW" << std::endl;
        return -1;
    }

    init();

    while (!glfwWindowShouldClose(window)) {
        render();
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwTerminate();
    return 0;
}