[Sidefx-houdini-list] Sprites and Mantra

Andrew D Lyons tstexture at gmail.com
Mon Oct 16 13:26:06 EDT 2006

I had this problem once with leaf shapes on square cards. I seem to
remember something  being added to mantra afterwards which solved this
problem. Maybe it was this (look in deep raster tab of mantra rop):


Sample Filters (Mantra)

A sample filter determines how a list of samples is collapsed to a
single sample value, for later application of a Pixel Filter. Sample
lists will usually only have a single entry for a fully opaque
surface, but may be larger when many semi-transparent objects cover
that pixel. Sample filters are only available for deep raster planes.

    * Closest surface - The value from the closest surface is selected.
    * Opacity filtering - The sample values are composited using the
surface opacities.

For extreme power in post-processing rendered frames, render into the
compositor and use the compositor to process the frames.


So I'm guessing you should try "Opacity filtering". Give it a whirl
and tell us if it works. Sorry for not being more helpful if it
doesn't. :)


On 16/10/06, Jean-Claude <jclaude at mimgfx.com> wrote:
> Hash: SHA1
> Hi Guys,
> I'm having problems with sprites that now i cant even count how many I have...
> but I need a solution for this first problem... how do I tell mantra .... how many overlapping sprites to consider?
> is there a sort of "ray depth"?... I have a sphere which emit static particles... and such particles are shaded with a
> VOP shader which makes a gradient opacity...
> when sprites overlap (quite always in my case) I've got a square.. with black area where it should be transparent...
> Alpha in mplay is what I'd expect.. its ok... but color... nope.
> thanks for any help....
> p.s. I'm trying to make a smoke effect with sprites...
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> .: mimgfx dot com
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Andrew D Lyons | Digital Artist | http://www.tstex.com

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