Culling, VRayMeshExport, PRT Reader

[TubeSmokeGuy]

Hi, I got some wishes

1. LiquidSimulator Mesh as animated VRayProxy with motionblur
When I do a VRayMesh export from a liquid simulator, the mesh saves out well.
But there are two things i noticed when exporing as animated proxy:
- it seems that no motion blur information is provided to the VRayProxy (when rendering the VRayProxy, there is no MotionBlur visible, but the original simulator mesh is blurred well)
- it seems that the frames are not in order (geometry is jumping during playback from earlier to later frames and so on (maybe an increment issue? when the frame increment rises from 0-9 (1 number) to 10-99 (two numbers) and 100 to 999 (thee numbers) and so on ... ))

My wish is that animated VRayProxies created from PHX LiquidSimulators work fine and with motion blur.

What I do for now is: I export the liquid particles as a PRT Sequence, load them in Krakatoa (apply some partice culling here if neccessary), feed them to Frost, try to achiev the closest matching mesh result compared to the liquid simulator mesh and then exporting the frost mesh as animated VRayProxy. That works. Even with motionbur and without frame jumps. But I need 2 more plugins and a lot of time ... which is bad.


2. Culling / cutting functionality for simulator particles (independent from PHX Foam Particle Shader in non-Geo-Mode) for use f.e. in VRayInstancer, PHX Foam Geomety Mode OR (maybe thats a wish for VRay) make VRayClipper work with VRayInstancer / PHX Foam in geomety mode.

Same here. If i want to cull particles i need to export them as PRT Sequence and do that in Krakatoa, but then i need another plugin ... which is bad.


3. I whish that you spend a little more love to the PRT reader ... maybe some time controls and culling options?

4. EDIT: Cryptomatte Support for PHX Foam Particle Shader ... independend from render mode.

5. EDIT 2: VRay GPU Support for PHX Particle Tex.

6. EDIT 2: VRay GPU Support for PHX Particle Shader.

7. EDIT 2: VRay GPU Support for all the other not supported PHX features.

Thank you!

[georgi.zhekov]

Hey,

Thanks for the suggestions - all them are in the to do list already so I have bumped up the priority on them.

For the VRayProxy - you could export the mesh to Alembic and load that in the Proxy, this way you can render with velocity. You can take a look at how this works here - https://docs.chaosgroup.com/display/...cachetoAlembic

Couldn't reproduce the jumping frames for the Proxy? Can you send us a scene for that?

Cheers,

[TubeSmokeGuy]

Oh super thank you for the alembic advice. I allways search for a direct connection to VRay, so the VRayMeshExport export just from the quad menue seemed very comfortable to me. Its very easy and intuitive and works without any warning or issue. The mesh was allways fine and I just wondered why the motion blur was missing. I know there is a special way how you produce the motion blur for the liquid mesh in phoenix (documented in the help), but I expected that during export the per-vertex-velocity will be calculated and stored in the proxy.

But with alembic i can spare the Krakatoa and Frost stuff, so thats a big relief. Thank you!

I will try to repro the frame jumping thing, unfortunaly I deleted allready the vrmesh File which was corrupt in that way.

[TubeSmokeGuy]

Okay I could reproduce it. But its described fast so i dont have to send you the big files i think.

My timeline was set to the framerange 64-181. I exported via quad menue vraymesh export, changed nothing in export dialog, just enabled the animation option and switched on "automatically create proxies".

But then (and i didn't noticed it), the proxy was on a different time position compared to the simulator, BECAUSE the exporter remapped frame 64 from the simulator to frame 0 of the proxy.

I didn't changed my timline and so what i saw was just the normal playback loop which was too early, caused by the frame shift (64 to 0). Hope that was clear .

[georgi.zhekov]

Ah I see, then you can just change the offset in the Proxy animation option and you should get the correct result or you can import the Proxy manually.

Looks like the offset range is not taken correctly only when using the "automatically create proxies" option.

Cheers,

[TubeSmokeGuy]

Okay, thank you!

In the description from the link you posted, of how I can export a simulators particle group to alembic, i noticed one little thing.
The particle groups of a simulator are exposed as hidden objects as standard. So when I just select the particle group from scene explorer and export as alembic (with particle export mode enabled in the simulator), then the alembic file becomes empty. I have to unhide the particle group object first before exporting and then the alembic file becomes written correctly.

Another point from the documentation I wonder about is: "3 You can assign V-Ray materials and Phoenix FD Particle shaders to the imported alembic files."

I can not pick a VRayProxy as source in the PhoenixFoam Particle Shader, or what do you mean with "Phoenix FD Particle shaders"?


BUUUUT

You can use VRay Clipper with VRayProxies .... so HURRAY culling / cutting of the phoenix particles is possible without any plugins. ... In the case when you direct render the particles from the VRayProxy. IT WORKS!

[georgi.zhekov]

For the invisible particle groups - make sure to get a more recent Phoenix build. With the latest builds the particle groups should be visible by default.

As for shading the alembic particles through VRayProxy with the Particle Shader - this is still in the to do list I'm afraid so the docs are fixed now.

I'm glad that you got the Clipper working If you have more questions, we'll be glad to help.

Cheers,

[TubeSmokeGuy]

Is there any reason why you flip the axis of the alembic at import and not already at export (in the export settings (from "Y is up" to "Z is up"))?

[georgi.zhekov]

In the Export dialog for the Alembic you can choose which axis is UP and on import you can choose to flip it if you wish - if you import files from Maya they need to be flipped for example.

Cheers,

[TubeSmokeGuy]

Ok thanks, just want to get shure if there could be any negative effect when switiching it already at export.

Another point from the doc thats not clear to me is:
" 2 When loading a sequence of Alembic files, you can use the '#' symbol as a hint to V-Ray that the file path is a sequence. 'C;\alembic_0001.abc' becomes 'C:\alembic_####.abc'."

When i write an alembic as shown in the documenation, I only get one file. Should I get a sequence?

EDIT:
Another point i noticed is, that when i export the particles like in the documentation, the particles will become no motion blur in rendering.

[georgi.zhekov]

The 3ds Max exporter automatically exports the whole animation as a single file so you don't have to worry about that - the message in the docs is in case you have a sequence exported and you need to load it.

In order to get motion blur for the particles you will need to have their velocity channel exported in the simulator's output rollout (note that you need to turn the checkbox separately for each particle group) and you need to export with the settings shown in the video.

Cheers,

[TubeSmokeGuy]

I did everything like in the video. The particles from the simulator got definately velocity information. When I export them as PRT Sequence, load them in Krakaoa and watch it with the Particle Data Viewer Utility i can read the velocity vectors for every particle.

Here I attached a rendering.

On the Rendering:
Left side: VRayProxy with Alembic Loaded
Right side: PHXFoam Particle Shader with the Particle Sequence directly loaded from the simulator

On the ViewportGrab:
Left side: PRT Sequece directly exported from the simulator and loaded with a Krakatoa PRT Loader, Display set to Velocities
Right side: VRayProxy with Alembic Loaded
Bottom: Krakatoa Particle Data Viewer Utility with velocity vectors present

[georgi.zhekov]

If you right-click on the VRayProxy - to to V-Ray Properties and enable the Velocity Channel checkbox, then set the Motion Blur Multiplier to 1000. As this is the Maximum value in the UI, but we need to increase it a bit more.
Close the V-Ray Properties window and right-click the Proxy again and go to Object Properties and from the User Defined tab set the VRay_MoBlur_Velocity_Multiplier to 4800.

This should give you proper motion blur. I will make sure to add the steps to the docs as well.

Cheers,

[TubeSmokeGuy]

Thank you! It works fine now.