[Sidefx-houdini-list] instance light + light mask

Stephen Tucker stucker at allegrodigital.com
Thu Jul 7 19:41:26 EDT 2011


You'll want to use categories when trying to do instanced light masking


> From: larry at gcreativestudios.com
> Date: Thu, 7 Jul 2011 19:04:07 -0400
> To: sidefx-houdini-list at sidefx.com
> Subject: Re: [Sidefx-houdini-list] instance light + light mask
> 
> Thanks for the feedback Skk,
> 
> I'll need to wrap my mind around that a bit. Gotta love the warning  
> in the description on that node under help.
> 
> Man, I thought there would have been a more straight forward way to  
> control light masks for instanced lights.
> 
> Larry
> 
> On Jul 7, 2011, at 6:30 PM, Szymon Kapeniak wrote:
> 
> > Hey Larry, the trick mentioned by Peter seems to work, but not in  
> > light masks on objects. Try masks in illuminance loop instead.  If  
> > I recall correctly this is because an instance name is treated in  
> > Houdini as an error (since such light doesn't exist yet), and never  
> > get passed to IFD file. Shaders parms are sent as such, so they can  
> > work with light's names valid only for Mantra.
> >
> > skk.
> >
> > Dnia 7 lip 2011 o godz. 23:27 Larry Giunta  
> > <larry at gcreativestudios.com> napisał(a):
> >
> >> Thanks Peter. I guess this is not as easy as I had hoped.
> >>
> >> ok, I do find this syntax for the light name in the IFD.
> >> ray_property object name "/obj/light1:/obj/instance1:0"
> >>
> >> However, I'm trying all kinds of variations of that name in the  
> >> light mask and still no luck.
> >> Looks like it might be time to hit up support for thoughts on this  
> >> unless the above info provides any clues to you.
> >>
> >> Thanks again for your help and feedback.
> >>
> >> Larry
> >>
> >> On Jul 7, 2011, at 3:49 PM, Peter Bowmar wrote:
> >>
> >>> Hi Larry,
> >>>
> >>> As I recall, this is tricky but possible. The issue is that the
> >>> instanced lights get renamed by the instancer. I think you have to
> >>> look inside the IFD file to get the "actual" name of the instanced
> >>> light... If the light is "MyLight" in the Houdini file, it might
> >>> become "MyLight-1" or something but I forget exactly. Sorry I can't
> >>> help more...
> >>>
> >>> Cheers,
> >>>
> >>> Peter B
> >>>
> >>> On 7 July 2011 09:55, Larry Giunta <larry at gcreativestudios.com>  
> >>> wrote:
> >>>> hello all. I hope this is a simple question.
> >>>>
> >>>> I'm instancing a light to an object with one point ( because the  
> >>>> light needs
> >>>> to be placed inside/stay with a translucent object animated in  
> >>>> DOPs)
> >>>> I also have other lights in the scene.
> >>>>
> >>>> I want this one object to only be illuminated by the instanced  
> >>>> light and not
> >>>> any other lights in the scene.
> >>>> However, I'm not sure how to enter this in the light mask.
> >>>>
> >>>> It seems that if I enter anything other than * I don't get any  
> >>>> illumination
> >>>> on that object.
> >>>> I've tried entering the instanced object and the source light  
> >>>> explicitly.
> >>>> I've also tried entering * and then eliminating lights with  a ^  
> >>>> string ....
> >>>>
> >>>> but unless I enter a wide open * I don't seem to get any  
> >>>> illumination on
> >>>> this surface.
> >>>>
> >>>> Any thoughts??
> >>>>
> >>>>
> >>>> Thanks,
> >>>>
> >>>> Larry
> >>>>
> >>>> _______________________________________________
> >>>> Sidefx-houdini-list mailing list
> >>>> Sidefx-houdini-list at sidefx.com
> >>>> https://lists.sidefx.com:443/mailman/listinfo/sidefx-houdini-list
> >>>>
> >>>
> >>>
> >>>
> >>> -- 
> >>> Cheers,
> >>>
> >>> Peter B
> >>>
> >>> --No, I am not on Facebook.
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> >>
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