Hi,
I'm writing a matte shader that (among other things) catches indirect light from surrounding objects. Since I want the resulting composite to be purely additive, I've got the shader outputting the indirect color, opacity of 1, but alpha of zero.
It seems that Mantra renders no color in this case, although if I bump the alpha up a tiny amount (say to 0.00001), the color shows up fine.
I made a quick test shader, shown in the screenshot. This renders black in Mantra, though if I bump the constant “ZERO” node up to a nominal amount it shows up fine.
What am I missing?
Thanks
Found 183 posts.
Search results Show results as topic list.
Technical Discussion » Zero Alpha leads to no color from Mantra?
- johner
- 809 posts
- Offline
Technical Discussion » CHOPnet cook within ForEach problem
- johner
- 809 posts
- Offline
So I went through Peter's cool tutorial at:
http://www.sidefx.com/images/stories/tutorials/spring_sop/4.chops_animation_curve.mov [sidefx.com]
which extracts a curve from a NURBs surface and uses CHOPs to animate a sphere along it.
I figured this would be an interesting thing to expand to an arbitrary number of curves and spheres using the ForEach SOP, but it doesn't seem to work. Basically when I put the CHOPnet into the ForEach SOP it only seems to cook the CHOPnet for the first iteration, meaning all the spheres are moved along the first curve only.
If I do the exact same setup but use a “point” expression in the subnet to animate the spheres, rather than an exported CHOPs channel, it works great. See attached file.
Am I doing something wrong? Should this work?
Thanks
http://www.sidefx.com/images/stories/tutorials/spring_sop/4.chops_animation_curve.mov [sidefx.com]
which extracts a curve from a NURBs surface and uses CHOPs to animate a sphere along it.
I figured this would be an interesting thing to expand to an arbitrary number of curves and spheres using the ForEach SOP, but it doesn't seem to work. Basically when I put the CHOPnet into the ForEach SOP it only seems to cook the CHOPnet for the first iteration, meaning all the spheres are moved along the first curve only.
If I do the exact same setup but use a “point” expression in the subnet to animate the spheres, rather than an exported CHOPs channel, it works great. See attached file.
Am I doing something wrong? Should this work?
Thanks
Technical Discussion » occlusion Vop
- johner
- 809 posts
- Offline
I'm using apprentice version 8.1.655, and I believe I just ran into the same bug with the irradiance VOP. It's just a typo, but the generated vex code should be providing a value for the “environment” parameter, not “envmap”.
-
- Quick Links