#bitmap shadows?
Phil, Ya gotta help me. I'm doing something I thought would be a snap and it's
turning out to be an impossibility. On the first page of "Colorplate Samples"
in the r3 Reference Manual (right after page 8-152), image 8 shows opacity
mapping.
What I see there is a bitmap image (concen.tga) projected onto the solid
geometry of an umbrella, with a shadow-casting spotlight shining on the
geometry. The way the bitmap image drapes over the geometry determines the
appearance of the shadow, not the geometry itself.
I'm trying to do something that I think is very similar if not identical. I'm
trying to show trees on a site plan by mapping .TGA images of trees onto
rectangles and using ray-tracing spotlights to cast shadows of the trees, not
the rectangles. It's not working. I can remove the shadow of the rectangle OK,
and the image of the tree shows up OK, but I can't get the image of the tree to
cast a shadow. The only shadow I can get is of the rectangle. Yes, my light is
ray-traced. I've tried about a hundred possible combinations, but not the
right one.
I'm e-mailing you the very small .PRJ file I used for testing. When I started
trying to do this, I was using a 24-bit .TGA scanned tree and a 1-bit .TIF
conversion of the same tree as an opacity map. I replaced the tree .TGA and
.TIF w/ CONCEN.TGA off the WCT CD-ROM, so I'm not sending that.
I'll buy your R4 book if you can solve this <bg>. I've got the R3 edition, but
can't find the answer there.
Thanks very much for all your recent help. Joe Miller