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fixxorion

Particle Color

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Hi all!

I'm learning particles in Houdini now, but have run into some problems...

I created a Particle SOP, appended a Point SOP to it to change the point color based on the distance from the origin, and it shows up great in the viewport. However, when I go to render it out, it shows up as white!?! Appending a Shop SOP with a different shader worked, but that has nothing to do with the point color. I'm really at my wit's end here...please help me. :(

Thanks,

fixxorion

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relax :), here's why:

Mantra, houdinis renderer, works with shaders, and not all of them are written with consideration. In order for an attribute (such as point color) to be passed over to the shader, the shader actually has to look for it. Some shaders will do this ( I belive the vex super material does) but others do not. However, if you find out what attribute it's using for color, you can actually rename your color attribute, so that it gets passed in correctly.

Take for example the Vex constant shader. If you render your points with it, they'll all be white. Now append an Attribute sop. In the first rename field, rename Cd to clr . Now try your render again. If all goes right, you should now see colored points :). The secret is knowing what attribute the shader looks for. If you go into shops, keyframe the color chanels and scope them. You'll see that they're named clrr clrg and clrb. From this you can gather that the color attribute is clr (and rgb is appended to that).

Hmn... I hope this was somewhat clear. This was actually discussed a few times in this forum, so maybe you can do some searching to find more info :)

Cheers,

Jens

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Hi,

Thanks for the excellent reply...that does clear it up, but I still can't seem to get it to work. I attached the file...do you see how to make it work?

Thanks,

fixxorion

test.zip

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Ok, check it out. I used the two shaders you had in there to demonstrate how to do it. The renaming of the attribute happens in the attribute sops.

Hope this helps :)

-Jens

color.hipnc.gz

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