Geometry Procedural for Mantra

[Graeme]

Hi everyone!

I have posted this on SideFX forums also..

I'm hoping some of you procedural shader genius's might be able to shed some light on the topic of creating Geometry Procedurals for rendering in Mantra. 

I've spent some time researching online, particularly reading through the HDK documentation, and what I can ascertain thus far is that the process would be: 

code the proc shader in C -> Compile via Houdini terminal(Mac) -> get the .dylib(Mac) files into the houdini/dso/mantra folder -> create a new operator type, of type SHOP-Geometry/Procedural Shader and in the Node tab change the Shader Name to be the same as your Shader Name in your shader -> apply the shader to the geometry's render/geo tabs Procedural Shader parameter.

This is the basics of what I did with the VRAY_DemoBox and it seemed to work fine. I am wondering if this is the most efficient process…? Is it correct?

My end goal is to try and create a procedural that will render a surface blobby at render time by scattering points on my mesh (like the mesh in my video below) in Houdini, feed mantra the points from Houdini and have Mantra surface it via my procedural shader. 
Perhaps there might be a method to do this using Metaballs or VDB..? Maybe even isosurface..?

Thanks heaps for any input, comments and insight into this process!

Cheers

G

 

Edited August 4, 2016 by Graeme

[symek]

Although render-time procedural is great idea and all shiny and sexy, practically speaking Houdini/Mantra flexibility and interoperability makes difficult to justify efforts of creating really helpful plugin. The only true reason to go that path IMHO is production scale optimization, that is when you have to do some heavy task for hundreds of shots. Other then that, using usual work with sending geometry from Houdini to Mantra turns to be the best approach - at least from my experience. 

When you say blobby surface, you mean metaballs like? Why not to use metaballs or render time surfacing of SDF? What is the reason of not meshing  or instancing and meshing in Houdini where you can post process geometry whatever you want? 

Shortly put, Houdini allows you to go crazy with packet primitives, volumes, hand-tuned VDB surfacing, point replication, so custom C++ is really the last option IMHO unless you see a good reason or just want to learn new things. 

[Graeme]

Hi there Szymon!

Thanks heaps for the response and insight!

I did mean metaball like or vdb.

I am literally only trying to accomplish this as a means to learning new things in Houdini and grow my understanding of how this could work in a big pipeline and I find this kind of optimisation quite interesting. 

Render time surfacing of SDF sounds promising, would you just accomplish this through the VEX volume procedural?

thanks!

G