BBS: Inland Empire Archive Date: 05-06-92 (23:44) Number: 149 From: DAVID BLISS Refer#: NONE To: RICH GELDREICH Recvd: NO Subj: projection Onto Plane. Conf: (2) Quik_Bas

> Lets say we have a four sided plane in 3-D space, > like this: > x----x > ! ! > ! ! > ! ! > x----x > Where each "x" has an X,Y, & Z coordinate. The > plane could be in any > position, not just what you see here. > What I need: The coordinate of a point which is > perpendicular to > this plane when a line is drawn threw it to the center > of the plane. If > that isn't hard enough, the point must also be a > certain distance from > the plane too(such as 64 units or so). I can easily This is so amazingly simple <g> (no offense of course!). To find X,Y,Z of the point you said (assuming i understand you), assuming the plane has four corners 1-4 and X,Y,Z of these are X1-4 Y1-4 and Z1-4 and the point you need is X5 Y5 Z5, X5=(x1-x2)+(x3-x4)/2 or whichever corners are on same line Y5=(y1-y2)+(y3-y4)/2 " " " " " " " Z5=(z1+z2+z3+z4)/4+64 What this does, is find the middle of the left side of the plane, then the middle of the top side, and then give you a point 64 units above that point. very simple geometry <bg> but then i'm in very advanced math <g> Hope this helps, Dave --- * Origin: The Aliens BBS, Simpsonville SC, 8032347195 (1:3639/4)

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