Texture from attribute for use in COPS without baking

[eyfox]

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]

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]

Thanks i will try that!

[hughspeers]

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]

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]

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 

[cudarsjanis]

On 6/4/2019 at 4:19 PM, hughspeers said:

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

Thank you for this! Exactly what I was looking for.

Cheers

Janis

[CinnamonMetal]

Is this an issue with COPS; it's not working ?

copimport_sops.hipnc

[hughspeers]

Hi Chris 

Its behaving oddly for me to, could be cache not sure. I opened your project in 17.5 it didn't work I opened my own it didn't work. I then went to H17 and my project didn't work until I edited it a little. It then worked . 

I copied and pasted my vopnet into yours and then edited a little then undid back to the original and worked . I did the same between H17 and H17.5 

Anyway cache or H17.5 bug I'm not sure, but this one works now (on my machine!)

  

copimport_sops_JB.hipnc

[CinnamonMetal]

9 hours ago, hughspeers said:

I copied and pasted my vopnet into yours and then edited a little then undid back to the original and worked . I did the same between H17 and H17.5

What did you edit to get my scene to work ?

[hughspeers]

Hi Chris 

I copied and pasted nodes from your scene opened in version 17 into a copy of your scene openned in version 17.5.

I was trying to debug it by version.  

When I mentioned editing it I meant typing in the snippet then undoing it so that it might update the cache.

So no apparent user logic

Does the file I uploaded work for you now ? 

Edited March 16, 2020 by hughspeers

[CinnamonMetal]

The file you uploaded works, I'm trying to see if I can get it to work in my original scene. No matter what I type and erase in the COP VOP it doesn't work.

Edited March 17, 2020 by CinnamonMetal

[CinnamonMetal]

I got it working, I think it was the computer.

[CinnamonMetal]

How do I get the data from COPS back to the SOPS Color Object Level; is there a way to use the COP2Net within SOPS to retrieve this data ?

[Richard]

You can do similar attribtue import with the labs attribute import cop (it is doing similar to the code above). To get it back out to sops just drag your final null into the texture slot of a uv quick shade and put op: at the start.