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3 Dimensional Chat / How are collision normals determined?

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Maxmax123
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Posted: 13th Jan 2009 02:45
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The title says it all I know a little but about them but Im not sure how they are determined after say a collision.

Im working with sparkie's collision and need to understand better how collision normals are calulated and how they could be interchanged with angle values when needed.


Thank you
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dark coder
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Posted: 13th Jan 2009 06:39
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They are likely stored for each triangle as recomputing them every time you intersect geometry would be a bit of a waste. The way they are calculated is by getting the 3 vertex positions for the current triangle and finding the tangent and binormal, vert pos1-2 and 1-3 respectively(depending on the triangle winding), normalizing them and the normal would be the cross product of those vectors.

Also this is the wrong board.

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Maxmax123
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Posted: 13th Jan 2009 15:33
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Thats some useful info but I still don't quite understand how normals are returned corresponding to the angle and direction of the collision.

Like what would be returned on a collision from the side compared to a collision from the bottom or top.


Also, this post relates to 3d things doesn't it?
Im not just asking this for sparkies dll alone, but for all things that use 3d normals.
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Sixty Squares
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Posted: 16th Jan 2009 21:09
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It does relate to 3D things, but it tends to be more oriented towards modelling than programming. Try the DBPro/DarkBasic/Newcomer's boards for collition questions.

As for the normals, I'm not sure how they work either .

Snow Demo
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