Viewing & Rendering

Visible Surface Determination--Back-Face Culling

Assumes objects defined as polyhedra
Use outward normal (ON) of polygon to test for rejection
LOS = Line of Sight, the projector from the center of projection to the polygon. (For parallel projections LOS = DOP = direction of projection).
Cosine of angle between LON and ON is used to determine if the polygon is back-facing or not:
- If LOS * ON < 0, then polygon may be visible
- If LOS * ON > 0, then polygon is invisible--discard
When displaying a single convex polyhedron, back-face culling is the only visible surface algorithm needed!

Generated with CERN WebMaker