use point attribs in volume

[Jesper Rahlff]

Hi guys.

I am trying to utilize my point attribs in a volume. how can I:

- set the volume color (shade the volume) using my point color?

- when volume is created, get it to read already set density values on the points. (volume rasterize).

 

attached is an example file.

 

cheers

colortovolume.hiplc

[Jesper Rahlff]

I solved the density problem, by simply bind the density inside the volume rasterize vop and multiplying it against incoming density.

now only thing left is to solve how to get my volume colorized according to my particles

[toadstorm]

easiest way is to use point cloud functions in your shader to read the points and get the average Cd in a radius, then use that as your volume color. if you need the colors in SOPs, it's more or less the same thing... pcopen() and pcfilter() in a volume wrangle to get the average P within a radius, then bind that to a Cd vector volume. just have to create the volume in advance, before the wrangle.

[Jesper Rahlff]

Thanks Henry. That did the trick. Exactly what I was looking for.

Appreciate you taking the time to reply.

 

Cheers

[Jesper Rahlff]

On 2018-07-19 at 3:57 PM, toadstorm said:

easiest way is to use point cloud functions in your shader to read the points and get the average Cd in a radius, then use that as your volume color. if you need the colors in SOPs, it's more or less the same thing... pcopen() and pcfilter() in a volume wrangle to get the average P within a radius, then bind that to a Cd vector volume. just have to create the volume in advance, before the wrangle.

@toadstorm any chance you can provide a simple example file? I thought I had it working but I was to quick on that one.

 

Thanks in advance

Edited July 24, 2018 by Jesper Rahlff

[adrianr]

@Jesper Rahlff Here you go. Sops and Shader versions inside.

volume_pc_colour_01.hip

[Jesper Rahlff]

On 2018-07-24 at 2:22 AM, adrianr said:

@Jesper Rahlff Here you go. Sops and Shader versions inside.

volume_pc_colour_01.hip

thanks so much man. appreciate the help

Interestingly enough I cannot get this to work with VDBs. Volumes work fine, but VDBs not so much

Edited July 25, 2018 by Jesper Rahlff

[adrianr]

@Jesper Rahlff Here is the file with VDBs, nothing really different. Is there a specific issue you're having with your scene you could share? 

I've popped in an example using the bunny from http://www.openvdb.org/download/ too so just download it from there if you want to see that. bunny_cloud.vdb is the file, top right.

volume_pc_colour_02.hip

[Jesper Rahlff]

I think the issue was that I was creating the Cd volume with the VDB node. using a volume node and converting that to VDB works fine.

anyhow, I ended up expanding on your shader approach and used that. Was perfect for what I needed to do.

Cheers for your time mate