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- Date: Mon, 26 Apr 93 22:52:53 MDT
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- From: "Michael Schroeder (Inf4 - hiwi)" <immd4.informatik.uni-erlangen.de!mlschroe>
- To: "Rayshade Distribution List" <cs.Princeton.EDU!rayshade-users>
- Subject: blob and shadow bug
-
-
- Hello,
-
- there is a small bug in the blob intersection code that makes
- rayshade miss blob hits if mindist is not zero. This can happen
- if a ray to a light source hits a blob. Example:
-
- --------------------------------------------------
- screen 120 100
- light 1 directional -1 0 1
- eyep 2 -10 3
- lookp 0 0 0
-
- surface glass
- diffuse 0 0 .5
- transp 1
- extinct .8
-
- blob glass .2 1 1 0 2 0
- box glass -.5 -2.5 -.5 .5 -1.5 .5
-
- plane 0 0 -2 0 0 1
- plane transp 1 -500 0 0 1 0 0
- --------------------------------------------------
-
- Patch:
-
- *** blob.c.orig Mon Apr 26 22:10:52 1993
- --- blob.c Mon Apr 26 22:25:01 1993
- ***************
- *** 250,256 ****
- /*
- * only interested in stuff in front of ray origin
- */
- ! if (dmin < mindist) dmin = mindist;
- dmax = b + t;
- if (dmax > dmin) /* we have a valid Region */
- {
- --- 250,256 ----
- /*
- * only interested in stuff in front of ray origin
- */
- ! if (dmin < mindist + EPSILON) dmin = mindist + EPSILON;
- dmax = b + t;
- if (dmax > dmin) /* we have a valid Region */
- {
-
-
-
- Note that the fully transparent plane is necessary because rayshade
- doesn't handle a light source in a medium with nonzero extinction
- coefficient. (There is still the problem that the surfaces are not
- held on a stack, but that's another story...)
- What do you think?
-
- *** shadow.c.orig Mon Apr 26 22:30:52 1993
- --- shadow.c Mon Apr 26 22:32:01 1993
- ***************
- *** 233,238 ****
- --- 233,244 ----
- */
- hitlist.nodes = 0;
- } while (TraceRay(ray, &hitlist, totaldist, &s));
- + if (prevsurf) {
- + if (prevsurf->statten != 1.) {
- + statten = pow(prevsurf->statten, dist - totaldist);
- + ColorScale(statten, res, &res);
- + }
- + }
-
- *result = res;
- return FALSE;
-
- Michael.
-
- ---------------------------------------------------------------
- Michael Schroeder mlschroe@faui43.informatik.uni-erlangen.de
- main(a){while(a=~getchar())putchar(~a-1/(~(a|32)/13*2-11)*13);}
-
- ----------
- Administrivia: rayshade-request@cs.princeton.edu
- Mailing list: rayshade-users@cs.princeton.edu
-
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