3D Clipping

• When do we clip in 3D? We should clip to the near plane before we project. Otherwise, we might map z to 0 and then x/z and y/z are undefined.
• We could clip to all 6 sides of the truncated viewing pyramid. But the plane equations are simpler if we clip after projection, because all sides of volume are parallel to coordinate plane.
• Clipping to a plane in 3D is identical to clipping to a line in 2D.
• We can also clip in homogenous coordinates.

Readings: Red Book, 6.6.4; White book, 6.5.4.