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Decal Mapping

Started by Brother Erryn Jan 24, 2003 at 8:52 AM 7 replies 600+ views

Original Post

Jan 24, 2003 at 8:52 AM

Where can I find information on this? For those that don't know what it is, it's where a decal conforms to complex geometry. I've Googled myself senseless without success. [edited by - Brother Erryn on January 24, 2003 3:04:16 PM]

Brother Erryn

Author

Brother Erryn

Jan 25, 2003 at 7:04 PM

Hmmm....have I stumped everyone? Or did I not explain what I''m after well enough?

Basiror

139

Basiror

Jan 25, 2003 at 8:27 PM

draw you map

then take your decals disable deapth write
enable blending and use the stencil buffer

Brother Erryn

Author

Brother Erryn

Jan 27, 2003 at 7:44 AM

But wouldn''t that stretch the image on non-perpendicular polygons?

Basiror

139

Basiror

Jan 27, 2003 at 9:12 AM

well you can should be able to calculate a quad for the decals

the math behind that isn t very difficult

Brother Erryn

Author

Brother Erryn

Jan 27, 2003 at 9:51 AM

But it wouldn''t be a single quad if it stretches across a dozen or more different triangles with different normals...the math to do that is what I''ve been looking for.

darookie

121

darookie

Jan 27, 2003 at 11:10 AM

Actually it's still a quad in the first place.

You need to test for polygon intersections with each of the quads sides. If they're all inside the same poly, you're ready to render by using the interpolated normals of the this poly.

Otherwise you need to split it up (both, pixel and texture coords).

This algorithm is performed recursivly, until all sub-quads are located within a single poly.

Hope that makes any sense