VRayLightMtl applied to tyFlow particles not rendering.

[ThomasMiller]

Am I doing something wrong or does V-Ray GPU not render tyFlow particles with VRayLightMtl? I'm using V-Ray 6 1.1, 3Ds Max 2024, latest version of tyFlow... Neither CUDA nor RTX seem to work

[hermit.crab]

How are you instancing the geometry and is the VRayLightMtl's Direct Illumination option active? What surely works (and can even instance VRayLights to tyFlow particles) is using the VRayInstancer. Choose the tyFlow particle system (the tyFlow Particle interface must be active) and instance your geometry, which has a VRayLightMtl applied.

[ThomasMiller]

I neglected to mention that I was trying to render from a tyCache as opposed to an active flow, since that's the only way I could get motion blur to work with GPU rendering.


Yes, the intention is to have direct illumination active. The only way I got direct illumination to work so far was by using the CPU to render, and having the mesh operand in tyFlow set to "triangle mesh," if I set it to "render instances" which I assume is tyFlow's native VRayInstancer, it works but I lose the direct illumination. I tried using the VRayInstancer object but it doesn't allow me to select tyFlow particles.


The geometry was a generic 3D sphere created by tyFlow's shape operant. I tried referencing an object from the scene instead, but the same problems persist.

Let me know if you'd like me to send the scene file

[hermit.crab]

...if I set it to "render instances" which I assume is tyFlow's native VRayInstancer, it works but I lose the direct illumination.

This is a known thing. Check this thread.

I tried using the VRayInstancer object but it doesn't allow me to select tyFlow particles.

As I mentioned earlier, you need to activate the Particle Interface (tyFlow object > Interfaces > Enable Particle Interface).

Otherwise, I can't seem to find a way to make tyCache files render with DI on GPU. Your best bet would be to use an active flow with VRayInstancer. Both motion blur and DI work fine like this.

[ThomasMiller]

Thanks hermit.crab. Active flow with VRayInstancer worked (with tyFlow object > Interfaces > Enable Particle Interface on). The only challenge that I ran into now is that the motion blur on GPU production rendering looks completely different than what it looks like in GPU IPR, and CPU PR and IPR.

[hermit.crab]

Thanks hermit.crab. Active flow with VRayInstancer worked (with tyFlow object > Interfaces > Enable Particle Interface on). The only challenge that I ran into now is that the motion blur on GPU production rendering looks completely different than what it looks like in GPU IPR, and CPU PR and IPR.

It seems that CPU rendering in 3ds max produces the wrong motion blur result since rendering in standalone produces identical to the V-Ray GPU results. I'll investigate further.

EDIT: Logged an issue (internal bug-tracker id: VMAX-13311) for it.

[ThomasMiller]

Thanks for looking into it hermit.crab. Just my two cents... the CPU motion blur is the one that looks correct to me, but that might be because that's the motion blur that I'm used to.