Re: Blackhole or black matte in renderman shader

llikethat <bharanitn@[EMAIL PROTECTED]
> wrote:
> I was trying to create a black hole or black matte of an object

It sounds like you want a 3D holdout matte.  Matte objects are shaded
black, hide objects behind them, and leave a hole where alpha = 0 in the
final image.  Objects nearer than the matte are rendered normally.  In
RenderMan you specify a matte object in the RIB (not in the shader):

    AttributeBegin
        Matte 1
        NuPatch ...
    AttributeEnd

See RiMatte() in any RenderMan reference.


Rick LaMont
Dot C Software, Inc.
http://www.dotcsw.com/