Hi, I am looking for a (possibly free) tool that allows me to create polygons out of a shape. For example, I would give this tool a star, and it would give me the polygons that would create it any ideas? thanks so much Joel [Edited by - JoelBenM on December 13, 2007 2:38:23 PM]

How are the shapes defined? If you are defining your shapes as a set of vertices on a plane, then Delaunay Triangulation may be able to do what you want. There may even be tools that will compute the Delaunay triangulation of a set of vertices for you, but I don't know of one off the top of my head. Maybe that will give you something to search for.

thanks. I should have been more specific. I'm looking for a tool where the input would be an image (say, a BMP file of black and white star) and the output is a triangulation of that star

thanks!
Joel

Just download a 3d program and point click the star and make it. When making any model usually u load a ref image. In your case a star and you can outline it with vertices and then your done.

You're basically trying to vectorize a bitmap here, and then subdivide the vectored shape into triangles. For the first bit, I don't think you have many options beyond just walking around the perimiter of the image, converting each pixel into a vertex, and then smoothing the result until you don't have a ludicrously large number of vertices.

I briefly considered trying to do something like this for my game project, where I'm using bounding convex polygons for sprite-sprite collision detection, but ultimately I decided I'd get better results by doing them by hand. A bit tedious, sure, but at least it's straightforward.

What you want can't really be done easily. As a simple example consider this image. Which shape would it create polygons for: the candle stick or the two faces?



For any program to auto triangulate there must be very specific input parameters defined. I have seen a couple applications that attempt to solve this problem but I don't know of any that yet work well. I may be behind the times here so someone please correct me if I'm wrong about the current state-of-the-art. [smile]

The easiest thing to do is what others are suggesting: Get a modeling program, import a reference image and create the polygons yourself.

-me