c++ - Opengl 与 gluPerspective 的混淆

Question

大家好，我是 opengl 的初学者，正在尝试理解 gluPerspective() 函数的概念。我浏览了这篇文章 gluPerspective parameters- what do they mean?发布，我写了这段代码

glClearColor(1.0,1.0,1.0,1.0);
glClear(GL_DEPTH_BUFFER_BIT);
glViewport(0,0,500,500);
gluPerspective(45,16/9,1.0,3.0);
glColor3f(1.0,0.0,0.0);
glBegin(GL_QUADS);
    glVertex3f(100.0f,0.0f,2.0f);
    glVertex3f(0.0f,0.0f,2.0f);
    glVertex3f(0.0f,100.0f,2.0f);
    glVertex3f(100.0f,100.0f,2.0f);
glEnd();
glFlush();

这是显示功能，但呈现黑屏。我的代码有什么问题

Answer 1

在调用 gluPerspective 之前调用 glMatrixMode(GL_PROJECTION);。
之后使用 glMatrixMode(GL_MODELVIEW); 切换回来。