GlOrtho and glFrustum
It was recently explained to me that while we typically do our thinking in a right-handed coordinate system, the screen is a left-handed coordinate system. One of the consequences of this
is that if you use
glOrtho (-1, 1, -1, 1, 1, 3)
and keep your drawing in the negative range (-3 < z < -1), then it works perfectly and you never get a near/far clip. The same thing applies to
glFrustum (-1, 1, -1, 1, 1, 3)
but it causes a problem. The resulting dimensions in the "perspective" view appear to increase with distance rather than decrease.
Can anybody explain this without a camera analogy? Can anybody explain how to do this (control z clipping and obtain correct perspective) without GLUT?