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View Full Version : Projecting curve to 3D object



mphanke
04-09-2002, 07:42 AM
Hi,

could some one please help me out with a snippet on how to project a closed curve on a 3D surface??
What I'm trying to do is to select and color a region on a mesh by a circle, elipse or a square. This all has to be done in perspective view.
I'm not sure whether this is a real beginner question but...

Thanks,

Martin

Furrage
04-10-2002, 09:09 AM
This sounds like something that using the stencil buffer will help to do, much like how they use it to create shadows. However, I know nothing about stencil buffers. Hopefully someone else can provide more.

Alternatively, you can figure it out using vectors. Essentially you create a prism from your shape by extending it along the -z axis. Then you check each vertex to see if it falls in that prism. Finally colour the ones that do.