This seems an obviously stupid question. But I cannot see a way to make normal (texture image) based Mental Ray meterials in Houdini. VEX only has nodes for Mantra, and included MI shaders (SHOP menu) don't have any slots for texture maps. Can Mantra VEX material be used with Mental Ray?
Additionally I am getting crashes when I trie to render (with MI) geometry thats uses MI_DGS and MI_Dielectric shaders.

DR

This is continuation from previous post. But I just do not understand how Houdini and Mental Ray are integrated. Where is the connection, aside from mental Ray ROP? There is no way to make decent materials. And the connection is unstable, and not usable. The results make no sense to me. If I do region render, I get results that do not show results of applied shaders or lighting. When I output an RGB image to file, that file is all black? The tutorial at http://www.techimage.co.uk/pdfs/houdini_mental_ray.pdf [techimage.co.uk]
makes no sense whatsoever. It shows MI shader codes, but where are they typed in, (Text editor, Textport, where?).

As far as I know, Houdini does not offer a shader authoring environment for MentalRay shaders, as it does for Mantra (and RenderMan since 6.5). So you should author your shaders elsewhere (by writing and compiling C-code or by using some shader authoring tool).
In Houdini, as far as I can tell, you can have SHOPs for your mental ray shaders so you can use them as any other shader (at the object level or with the Shader SOP). In the Shading tab of objects there are also some MI specific SHOP fields.
I suppose that at this moment the render region does not work with Mental Ray (its ability to work with RMan is one of the advances of 6.5).
As for the black rendered file, there is probably something wrong with your environment setup, and MentalRay does not find its shaders.

Dragos

That's correct - Mental Ray is currently implemented the way Renderman used to be(and still sort of is, for that matter, apart from the shader network). You're required to manage things like paths to shaders and resources since MR is a separate program. It's also expected that you're going to code your shaders in the traditional manner, and you can import them into Houdini as SHOPs for the interface. What Houdini does offer is actually quite substantial, however - the interface to MR is “invisible”, inasmuch as you don't need to have pages and pages of special MR-specific stuff - Houdini does the best it can to translate mantra-style aspects into MR for you. That's actually preferable IMHO to having masses of popup tabs for doing this.

Cheers,

J.C.

I remember the shop I was working for getting the first cut of PRMan (about 9+ years ago) and the slight panic at realizing that $7,000 US (or was it more back then?… can't remember) basically got you a book (The Renderman Companion), a shader compiler, a command-line application….. and the mother of all learning curves!

The immediate question is: “What!?… So; like every one of those movies has been using paintedplastic.sl for all those effects!?!?”

Closely followed by “OMFG! look at that motion blur!…. and the SPEEEEEEEED!!” (back then it was more impressive, you see)

OK. so $7,000 got you a *really nice* command-line app. But there was still that learning curve thing…


So; I understand your frustration, but… well… it is what it is, so why not start loving it!?…
Just *think* of all the ray-traced trouble^H^H^H^H^H^H^Hgoodness you could get into!!


Cheers!

Jan has some mentalray shader tutorials using Houdini over at techimage:
http://www.techimage.co.uk/products/houdini/houdini_tutorials.html [techimage.co.uk]