如何在OpenGL正交模式下用矩形填充屏幕？

glViewport(0, 0, display->w, display->h);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

double aspectRatio = (double)display->w / (double)display->h;

if (display->w <= display->h)
    glOrtho(-1, 1, -1 / aspectRatio, 1 / aspectRatio, -1, 1);
else
    glOrtho(-1 * aspectRatio, 1 * aspectRatio, -1, 1, -1, 1);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();