Full_Name: Bill Simpson
Submission from: (NULL) (126.96.36.199)
Bug in persp() bounding box:
If the surface being plotted extends below the lower z-axis boundary, the box
drawn with the wrong occlusion. The box is shown as being occluded by the
even though it should be in front of the surface.
The box is correct for surface extending above the box. Problem is only for
surface extending below the box.
This exhibits the bug:
std<-rep(seq(-32,32,8),9)/1000 * 60
persp(std,cf,dp, xlim=c(-2,2), ylim=c(-2,2), zlim=c(0,5),theta=-40,
The persp algorithm does not apply the occlusion rules to the frame,
which is always plotted first.
A bug, but not very simple to fix.
Audit (from Jitterbug):
Wed Jun 30 19:31:18 1999 pd moved from incoming to Graphics
Thu Jul 01 18:19:48 1999 pd changed notes
Sun Feb 20 10:07:11 2000 ripley changed notes
Mon Feb 28 17:17:51 2000 pd changed notes
Mon Feb 28 17:18:28 2000 pd changed notes
Mon Feb 28 17:19:35 2000 pd changed notes
Mon Feb 28 17:20:17 2000 pd changed notes
In fact the box is plotted twice, but edges of faces facing backwards
are plotted first.
The problem is that the *lim were chosen so that the surface was not
entirely within the box. The help page now warns about that.