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# Point & Plane easy question

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this hsould be pretty simple, but I want to know how to find out if a point is infront of, behind, or on a plane when you know the planes normal (3D math is a little confusing to me right now, because no one''s explained it to me formally and I''m only in 10th grade). Thanks.

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What you do is take the dot product between the planes normal and the point you want to check. You then subtract the distance of the plane to the origin (this is the value "D" in the plane equation, and can be found by taking the dot product between the normal and a point that you know to be on the plane).

Now, if this final dot product is greater than 0, the point is in front. If it is equal to 0 (or really close by some epsilon value), then it''s on the plane, and if the dot product is less than 0, then it''s behind the plane.

If you want a more elaborate mathamatical definition, I could go into detail. That''s just the bare bones though

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That helps a lot -- I just need the functionality really. ALthough what you said makes sense. Thank you again.

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Wait... wouldn''t just taking the dot product of the normal and the point and testing that against 0 tell you?

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