JeremyR
Hey all,
Just for fun Im looking at a Bifrost liquid sim but rendering the particles as spheres. Anyone know how to pipe the current velocity colours into an Arnold Shader for render?
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ytsejam
I did the same thing yesterday. You need to use the combined nodes in the image.
 
Click image for larger version - Name: node_vector_bifrost.jpg, Views: 8, Size: 145.06 KB
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JeremyR
Awesome thanks, Ill try it out.
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JeremyR
Tried velocity in the channel part of the aiUserDataVector but Im getting a B/W render only also tried creating 2 other remap nodes for the X and Y outputs to plug back into the base colour but not happening, any ideas?
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ytsejam
did you created a ramp? aiUserdataVector.output>aiRange
aiRange.output_B> ramp_V
ramp_V.outputrgb to aiStandarVolume scatter or aiStandardMaterial
You need to increase the inpput max of airange or remapValue.
Anyway i wil create a scene for you. As soon as possible.
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besha1
[47whfC4]
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ytsejam
besha1 wrote:
[47whfC4]

Yes. but if you want control the color, to have a non vector standard color. You can add a aiRange\RemapValue  and Ramp.
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besha1
Yes but the question was specifically about the velocity color
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JeremyR
Cool thanks guys.
Couple of things: Firstly I wasnt sure the render channel on the liquid shape had to be set to velocity which I had done so anyway but I was still getting gray output.
So I plugged the aiUserDataVector straight into base color of the arnold shader and started getting RGB results based on velocity. Not quite there yet though, Im trying to emulate the default liquid bifrost colors blue and white.

So I added in the remap and ramp nodes and changed the ramp color to blue - things starting to look like what it is supposed to now except only the values facing the z direction are white obviously because Im only reading the z channel from the aiDataVector. I tried replicating this setup for x,y and z but not getting the proper desired look, see attachment. 

Cheersnodes.png
I know I have not hooked up x and y to the shader because if I do I end up with multi coloured velocity and I dont want this.
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besha1
Use aiUserDataVector->aiLength->remapValue out color not out value to diffuse color .
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JeremyR
aiLength thats what I was looking for! Thanks for you help guys 🙂
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