Hi……

When writing Mantra Vray Procedural, how to change the transparency ???
There is a “changeSetting” function available in Vray procedural, but don't know if there is any option for transparency.
Don't know if it can be controlled through Vray procedural.
Basically, I want to use it to implement LOD in mantra. As projection size will decrease, blending will happen over two
detail models using Transparency.
Is there any other method to do this???

Hi…..

When I was browsing thru Rederman Docs, found that, there is a RiOpacity method available to control the opacity.
What is the parallel method in Mantra???

Hi………

I have controlled the transparency using a trick. I applied a material to the procedural object and by overriding the “alpha” attribute in the Vray Procedural, I can control the transparency.
But I am facing a new problem.
What my previous idea was, while implementing LOD, to blend two objects,
we can add both the objects to the scene at same place and reduce the alpha of one object while increase the alpha of the other object gradually.

But If I add two objects say A with Green Color and B with Red color, and both of them have alpha = 0.5, the result is not a Yellow color, but some polygons renderd as red and some as green.
How to blend both objects?? How is it done in Renderman???

If you have multiple transparent objects at the same location in space, mantra has no way to know which is in front of the other, which can cause artifacts in the render. You might want to try offsetting the objects a little bit and see if the problem goes away.

Andrew

Is there any chance to modify alpha by such code from procedural?:
const char *name = “Af”;
const char *value = “0.3”;
int test = changeSetting(name, value);

Thanks!

? :arrow:

Wish
Is there any chance to modify alpha by such code from procedural?:
const char *name = “Af”;
const char *value = “0.3”;
int test = changeSetting(name, value);

Thanks!

No, these variables are solely defined by the shader.

So what changeSetting(name, value) for?

Wish
So what changeSetting(name, value) for?

Any of the properties which you can set on objects: Reflection mask, shading rate, surface shader (but not parameters inside the shader), motion factor, render sub-d, displacement bounds, etc. Basically, any of the properties defined in the IFD for the object (not the shader).

Oh, nice! Thanks, Mark

Hey guys
I noticed you have been mentioning a vray procedural, can i ask exactly what does the vray procedural do?
Below is an email from out render manager and it seems that the libvray.dll is failing when we try to render specfic frames. We arent sure whats causing the problem… Any help identifing the issue would be great.

We were recently trying to render a character pass which quite a number of frames. On our test sequence we're experiencing some crashes that occur on the same frame each time. So it's a reproducible error. We are using the win64 build 9.1.293 since we started the project using that build and to update at this point could alter some key assets etc.

In a bid to resolve these mantra crashes can you maybe shed some light on what is causing Mantra to crash giving this error report.

Faulting application mantra.exe, version 9.1.0.293, faulting module libvray.dll, version 9.1.0.293, fault address 0x00000000000b1e5b.

Thanks
Nick

VRAY procedural is a houdini class which methods is used for creating geometry on the fly during render