opengl:关于glutMainLoop()的问题 [英] opengl: question about glutMainLoop()

问题描述

有人可以解释glutMainLoop的工作方式吗? 第二个问题，为什么定义glClearColor(0.0f, 0.0f, 1.0f, 1.0f); 在glutDisplayFunc(RenderScene);原因之后，我们首先调用glClear(GL_COLOR_BUFFER_BIT); 然后定义glClearColor(0.0f, 0.0f, 1.0f, 1.0f);

can somebody explain how does glutMainLoop work? and second question, why glClearColor(0.0f, 0.0f, 1.0f, 1.0f); defined after glutDisplayFunc(RenderScene); cause firstly we call glClear(GL_COLOR_BUFFER_BIT); and only then define glClearColor(0.0f, 0.0f, 1.0f, 1.0f);

int main(int argc, char* argv[])
    {
        glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
        glutInitWindowSize(800, 00);
        glutInitWindowPosition(300,50);
    glutCreateWindow("GLRect");
    glutDisplayFunc(RenderScene);
        glutReshapeFunc(ChangeSize);
    glClearColor(0.0f, 0.0f, 1.0f, 1.0f);  <--
    glutMainLoop();

        return 0;
    }

void RenderScene(void)
    {
    // Clear the window with current clearing color
    glClear(GL_COLOR_BUFFER_BIT);

    // Set current drawing color to red
    //         R     G     B
    glColor3f(1.0f, 0.0f, 1.0f);

    // Draw a filled rectangle with current color
    glRectf(0.0f, 0.0f, 50.0f, -50.0f);

    // Flush drawing commands
    glFlush();
    }

推荐答案

glutMainLoop()仅运行特定于平台的事件循环，并根据需要调用任何已注册的glut*Func()回调.

glutMainLoop() just runs a platform-specific event loop and calls any registered glut*Func() callbacks as needed.

RenderScene().因此实际上glClearColor()首先被调用，而不是glClear().

RenderScene() won't be called by GLUT until you call glutMainLoop(). So in reality glClearColor() gets called first, not glClear().

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