This variable (default 0.5) gives the minimum number of pixels that must
be covered by a z buffer shadow triangle for being rendered. With the default
value, triangles are not rendered if they are smaller than half a pixel. This
increases the frame rate, but can lead to "holes" in z buffer shadows
of high polygon models. When using high polygon models, clip_size
should be set to 0.
Range:0 .. 1 (default: 0.5)
clip_size = 0;