Hi,
I m using tmesh2rad to generate smooth surfaces for rendering in radiance.
tmesh2rad allows to apply a colorpict pattern to the surface.
Now I want to have a transparency value (alpha channel) for each colorpict
RGB value.
In the workshop it was mentioned a few times that mixpict could be used for
this and
I know Carsten has written a patch that allows to load colorpictures with
alpha channel.
If I create a radiance file with tmesh2rad can I add transparency from an
additional grayscale
image (alpha values) using mixpict ?
Thanks
Bernhard
Bernhard Spanlang wrote:
I'm using tmesh2rad to generate smooth surfaces for rendering in
radiance. tmesh2rad allows to apply a colorpict pattern to the
surface. Now I want to have a transparency value (alpha channel)
for each colorpict RGB value. In the workshop it was mentioned a
few times that mixpict could be used for this and I know Carsten
has written a patch that allows to load colorpictures with alpha
channel.
If I create a radiance file with tmesh2rad can I add transparency
from an additional grayscale image (alpha values) using mixpict ?
Just put the transparency layer into a grayscale TIFF and covert to Radiance with ra_tiff -r, then use this picture in a mixpict. If you are mixing the surface material with nothing (as in a ghostly object), you would mix the material with the "void" placeholder. If you want to mix a pattern with nothing, then do the same but with the pattern rather than the material.
void mixpict alpha_mix
7 my_material void green alpha.pic picture.cal pic_u pic_v
0
I use the "green" function above rather than "grey" because it arrives at the same value with less computation for a grayscale picture. Obviously, you should replace the "picture.cal" and "pic_u" and "pic_v" file and variables with whatever matches your original pattern in order to get them to match.
Corrections to follow, no doubt.
-Greg