Triplanar mapping in an alembic workflow?

[NigelDerivco]

Hi there. I'm a senior lighting artist at a game studio, currently doing the shading and lighting of assets for a game trailer.

I'm at a bit of a loss here, but is it just not possible to use triplanar mapping in an alembic workflow? I'm pretty new to Vray, I'm currently in the middle of my first production with it. Prior to Vray, I was a Renderman user for two years, on a tv series and a feature film. I ran into the same issue using their 3d manifold (their version of Triplanar) but they offered a solution where you could freeze the vertex information in a Pref attribute on the geometry, and then point the 3d manifold node to that attribute so that the projected texture stuck to the deforming geometry, rather than swim through it.

Is there any such workflow for Vray? I've used the triplanar mapping node extensively on the assets I'm look developing. For example, one is an off road vehicle, where triplanar was used to add surface imperfections across the object, as well as drive the scale of the dirt material. It's worked brilliantly thus far, and the asset is approved and ready for production. It saved us having to perfectly unwrap every nut, bolt and other arbitrary geometry, and send it to our texture artist to hand paint all of this. But it's all for nothing if the method falls apart when the shader is applied to an alembic.

I've only ever worked in production environments where alembic's are handed over to the lighting/shading/rendering department, so I'm really hoping that I've simply missed something, and that ChaosGroup has indeed made provisions to use the triplanar node and procedurals textures in an alembic workflow.

Thanks for your time.
Nigel.

[yolov]

This should be working with VRay actually. How are you importing the alembic? Through a VRay proxy or with the maya alembic import options (cache > alembic cache > import)?

[NigelDerivco]

Hi there Alex.
Thanks for taking the time to reply.

I'm currently importing it through cache>alembic cache>import. As part of my automated pipeline, it's scripted to use that method. If I should be doing it via a Vray Proxy, I can look at implementing that.

I did a test where I imported an array of cubes falling down in a dynamic simulation from another package. I imported that into Maya (via cache>alembic cache>import), applied a shader with a noise procedural running through a Triplanar node connected to a VrayMtl, and attached to the alembic, but the array of cubes simply moved through the texture, it wasn't sticking to the individual cubes. So that leads me to believe that the same thing will happen to our assets once I get the alembics.

[NigelDerivco]

I just ran a test with one of our assets, a bug character. I randomly animated its controllers over 25 frames. Exported the geo as alembic (automated script, but using cache>alembic>export selected). I import that alembic (via cache>alembic>import alembic, and apply a noise procedural, piped through a Triplanar node, and did a quick render, but the bug moves through the texture, it doesn't stick to the geo.

If it's meant to work, then there's a problem with my workflow that I need to identify.

[yolov]

Could you share the scene with us?

[vlado]

You would still need both the Pref and Nref attributes stored with the Alembic asset in any case. We will have to check how to hook them up to the triplanar texture. (For other procedural textures this is usually done by adding V-Ray attributes to 3d placement node.)

Best regards,
Vlado

[NigelDerivco]

It works if I create a simple rig with geo parented under joints, then when I alembic the geo out, they inherit the translations/rotations etc, and the triplanar works. But if I create an alembic from one of our assets (unable to send that, unfortunately), which is a skinned character, then the imported alembic has no translation data, as it's just a point cache, and since the Triplanar node works in local object space, it obviously wont stick to the points. As Vlado rightfully says, we need a way of getting the Pref data frozen to an attribute on the geo, and plug that data into the Triplanar node, or the entire procedural pipeline we currently have falls apart.

I am on a deadline at the moment, and I think it's best for me to abandon the triplanar node and kick the asset back to the texturing department to hand paint dirt masks etc. It's clear that it's not going to work for us.

Thanks for your time. I hope this get's a solution in the near future, as it's an incredibly powerful tool to have in my workflow.