orient3d_fast
orient3d_fast(points, a, b, c, d) ⇒ number
Non-robust
Return a positive value if the point pd lies below the plane passing through pa, pb, and pc; "below" is defined so that pa, pb, and pc appear in counterclockwise order when viewed from above the plane. Returns a negative value if pd lies above the plane. Returns zero if the points are coplanar. The result is also a rough approximation of six times the signed volume of the tetrahedron defined by the four points.
NOTE: ported from http://www.cs.cmu.edu/afs/cs/project/quake/public/code/predicates.c
Kind: global function
| Param | Type | Description |
|---|---|---|
| points | Array.<number> | |
| a | number | index of point a |
| b | number | index of point b |
| c | number | index of point c |
| d | number | index of point d |