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eyfox

Texture from attribute for use in COPS without baking

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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 by eyfox

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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. 

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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

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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?

Screen Shot 2019-06-04 at 11.23.43 PM.png

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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 

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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

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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

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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 ?

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Posted (edited)

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 by hughspeers

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Posted (edited)

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 by CinnamonMetal

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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 ?

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