Jul 18, 2012
Post id: 310344 Report Item

I have a volume emitter set to cloud s/w for the particle type. I have an opacityPP attribute set to use a ramp for the opacity which is using a value of 0 at birth, 1 somewhere in the middle, and 0 at death. When playing my simulation in the timeline, the opacity appears to be working properly in a shaded viewport.

I have a fluid texture applied to the particles.

When I render in mental ray, the opacityPP seems to be ignored and the texture is rendering from birth even though the particle opacity is at 0 at that point.

Can anyone shed some light on this problem?


Jul 18, 2012
Post id: 310346 Report Item

an update: After much searching, I found that other people have found a solution to this and that solution is the particleSamplerInfo node.

after all my reading, it seems all I need to do is input the opacityPP into the particleSamplerInfo node, possibly add a reverse node, then output the p.s.i. node to the transparency of the fluid texture.

For all my efforts, I can attach the p.s.i. node to the transparency, but I can't hook up the opacityPP to it for some reason. Can anyone help?

Jul 19, 2012
Post id: 310357 Report Item

got it figured out. I had little knowledge of the particleSampler node and didn't realize it takes no input, it just samples the scene. After that it was just a matter of connecting the sampler to the proper spot on the reverse node. Hours of internet searching, forum trolling, and it just took a friend of mine who had a better knowledge of the sampler to explain it...sigh. Now my fluid is rendering properly. Hope this post can help someone out in the future.