Emiting Particles From Texture.

[red4kat]

Hello,

I am running into the following problem. I have a geometry with a mapped texture on it. The texture is simple, it's all black but in front has a white shape on it that expands over time. I need to have it set up so that the particles are emmited from only the white portion of this geometry. Does anybody have any idea on how to do that?

thanks,

Katherine

[aracid]

hey there

but as far as i know, u cant birth straight from a texture, u have to apply that texture onto the geom,

and then define a group on the geom based on some expression that queries the texture, either using the tex or pic expression.

check out the hip and a pic or tex expression within the point sop, and it should work.

brian

white.hip

[3dbeing]

I belive if you attach the texture as point color, you can use the $CD as birth probability, but I havn't tried, so I may be remembering wrong too.

-3db

[Steve Sloan]

Katherine - this is a simple expression that will work in the point SOP add color field

pic("source image COP", $MAPU, $MAPV, DC_LUM)

or

tex("source image file", $MAPU, $MAPV, DC_LUM)

this will get the luminance value from the texture file or COP according to the uv lookup maintained by each point

have a good weekend!