[Sidefx-houdini-list] houdini -> mental ray user datas
Guy Rabiller
guy at alamaison.fr
Wed Mar 22 18:41:22 EST 2006
Thanks Colin,
that's a start for me, very interresting. I'll investigate.
On a scene basis I can surely feed my custom datas through this
inclusion mechanism.
Now I have to figure out how to make the link between those datas and a
specific object instance.
By any chance, do you know if this mechanism is available on a per
object basis ?
Looking at the Shading tab of a model, there is a mental ray sub-tab,
where we can set mental ray shaders.
Idealy, I'm looking for the same idea but for the object description
itself, or mental ray 'attributes', may be a SOP node in wich we could
set mental ray attribute for this object ( or light, or camera, etc.. )
For instance a mental ray object Instance has attribute such as 'hide'
(on/off), 'shadow' (mode) and even 'data' ( data name ), the one I'm
interrested in.
May be I'm just overcomplicating things ? If I put an Attribute SOP and
use 'hide'/'on' it will be transmitted as this to the mental ray
instance description ?
Could it be that simple ?
I didnt try real exemple yet, I'm just trying to globaly figure out the
right way(s) to reproduce ( and extend ) the type of workflow we
currently have with XSI / mental ray.
( still very new to Houdini )
--
guy rabiller | 3d technical director @ LaMaison
Colin Doncaster a écrit :
>
> hey guy -
>
> each model has the pre and post include script which does get written
> out to the .mi file. You could write a pre-frame script ( in the
> mental ray ROP ) that runs a script to generates an .mi file for that
> frame and then set the pre/post include to that output.
>
> You can open a command port or stuff all the relevant object
> information onto the command line to get scene data.
>
> It's ugly ( ish ) but it should work.
>
> Oh, the other thing that occured to me, if you put a unix sop at the
> end of your sop network you could then pipe all the geometry data to a
> script that formats it into the per frame .mi you want which means you
> won't have to worry about the pre frame script in the output ROP.
>
> Just some thoughts.
>
> Cheers - colin.
>
> On 23-Mar-06, at 1:52 AM, Guy Rabiller wrote:
>
>> Hi,
>>
>> regarding mental ray rendering from within Houdini, is there any
>> built-in mechanism to transfert "user-datas" to mental ray
>> scenes/shaders ?
>>
>> In XSI for instance, there are what so called "UserDataBlobs" at a
>> scene or object level, wich can be 'filled' by ascii datas from
>> script or ascii/binary datas from c++ plugins.
>> Then at render time, XSI automatically send those datas as user datas
>> ( miQ_OBJ_DATA.. ) attached to the object containing the UserdataBlob.
>>
>> Is there such mechanism in Houdini ?
>>
>> If not, what could be the best way to handle this, to enable user
>> datas communication between Houdini and mental ray ?
>>
>> Thanks in advance.
>>
>> --
>> guy rabiller | 3d technical director @ LaMaison
>>
>>
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>
> --
> Colin Doncaster Some Guy -- colin.doncaster at rsp.com.au
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