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kenjinsakura

Point Polygon collision

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Hey all, I need to know if my cursor is over a polygon in 3d space. There's more than one polygon and I need to find the closest one that hits. The method I've come up with is: For each polygon Project the polygon vertices onto the screen (view, transform, projection matrices known) Using odd-even test, determine if cursor is in projected polygon. If it does then check the distance and compare to the distance of closest polygon found. I'm wondering if there was a better way to do it. Or if there's something wrong with the algorithm. Thanks in advance.

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Hi,

The method you describe should work just fine.

Another way of doing the same thing is to create a 3d ray from the mouse pointer coordinates and do ray-triangle hit test for each polygon.

this thread describes how to get the ray.

You can google for the ray-triangle hit test.

This method is useful also for raytracing and is maybe a bit more efficient since you don't need to project your triangles.

Good luck!

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