Texture from attribute for use in COPS without baking

[eyfox 0]

Hallo everyone,

i am new here. I have searched for a solution to this problem, but cant find one. I want to transfer a point-attribute from a polysurface with uvs into COPS. Just like it works with heightfields and the "Sop Import"-node.

I read that the qLib "uvPointCloud ql" would be the solution for this, but the node does not work for me. There is a warning that the "ray_ql1"-node inside is using an incomplete asset definition?

UPDATE: Solved the issue with the "ray_ql1" node by importing the asset manually from the qLib-folder, but still could not get it to work unfortunately.

Also found out that i could convert the polySurface into a volume and then get the colors from there into cops with "Sop Import"-node i guess, but not sure how to go about making the volume with the inherited color-attribute?

thanks,

Marcus

Edited March 5, 2019 by eyfox

[symek 346]

Not sure if I understand correctly, but if you want to bake in COPs point attribute in uv space, then VEX works as usual: 

vector uv  = set(X, Y, 0);
vector clr = uvsample("op:/obj/geo/geometry", "Cd", "uv", uv);
R = clr.x; G = clr.y; B = clr.z;

Copy this (replacing path and attribute name) into Snippet VOP inside vopcop2filter and you should have the attribute baked into texture. 

[eyfox 0]

Thanks i will try that!

[hughspeers 1]

Hi Symek 

I'm trying out your snippet suggestion but failing to get it to work. I think I'm missing some basic piece of the knowledge puzzle. 

I've made a simple example but I'm not able to see my colour attribute spread out in the cops viewport as a flattened uv image. 

Any light shed would be most appreciated thanks 

John

Attribute_to_cops_by_UV.hip

[symek 346]

I literally haven't done anything except changing constant color to bounding box to emphasize the effect and it does work here (17.0.416 - OSX).

COPS have some issues with refreshing. They might not notice your changes and keep displaying old image. Maybe this is your problem?

[hughspeers 1]

Hi Symek thanks for checking the scene file.

You are absolutely right it must have been cops cache problem.  When I opened it this morning its working. 

I'm often caught out by a cache problem in houdini and chasing my tail for an hour before I open and close a scene !

I see the qlib tools mentioned above by eyfox have a flush cache in the shelf tools, I'll give that a go.

Thanks again Symek 

John