# Ellipse collision detection (again)

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I know that this has been asked a few thousand times on the forums. Problem is, I can't see where its actually been answered. So I'll ask it in a very simplified form, given the following prototype, what would its implementation be? function CollideEllipses(E1CenterX, E1CenterY, E1XStretch, E1YStretch, E1Rotation, E2CenterX, E2CenterY, E2XStretch, E2YStretch, E2Rotation : UInt32) : Boolean; for those C junkies out there, here is my best shot at it in C: bool CollideEllipses(Uint32 E1CenterX, E1CenterY, E1XStretch, E1YStretch, E1Rotation, E2CenterX, E2CenterY, E2XStretch, E2YStretch, E2Rotation); Any takers, I've been scratching my head for a while on this and haven't been able to get it to work at all. Yes I've done some reading, and to be honest the math is just more then I have time right now to learn. Guess I could do with out the whole thing, but it would be nice to have it. - Jeremy

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 I know that this has been asked a few thousand times on the forums. Problem is, I can't see where its actually been answered.

You should learn to search the web, for example:

Which finds the nice summary of ellipse intersection by the invaluable Dave Eberly:
http://www.geometrictools.com/Documentation/IntersectionOfEllipses.pdf

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The majority of isometric games (all that I know of) use a tile-based system. This type of collision is near-useless in a tile-based world. Are you asking in the right forum?

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 Original post by LorenzoGattiYou should learn to search the web, for example: http://www.google.com/search?q=ellipse+intersectionWhich finds the nice summary of ellipse intersection by the invaluable Dave Eberly: http://www.geometrictools.com/Documentation/IntersectionOfEllipses.pdf

I did search the web, and GD, and PGD, and many many more. I found this paper in my searches as well. I just don't understand everything that it says, thats why I asked for something around a given prototype.

- Jeremy

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 Original post by EzbezThe majority of isometric games (all that I know of) use a tile-based system. This type of collision is near-useless in a tile-based world. Are you asking in the right forum?

I'm working on a tile based game who's sprites are ellipses, thus eliptical collision makes sense. If I can't find an answer, I have a fallback pixel perfect solution, but I believe that it will be slower then the ellipse version.

- Jeremy

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