 | | need Help finding a co-ordinate —Dennis Osborn
| | | | Does anyone have a program or an algorithm that does the following: Given four points in three dimension space (four corners of a quad,) and an (X,Y) co-ordinate on the quad, calculate the Z co-ordinate so the fifth point is on the quad. In other (...) (24 years ago, 11-Sep-00, to lugnet.cad)
| | | | | | | | | | RE: need Help finding a co-ordinate —Ralph Hempel
| | | | | (...) Ummm, if you mean co-planar, there is no guarantee that 4 points are coplanar in 3-space. however, 3 points are always coplanar. If the 4 points ARE coplanar, then throw out one of the points and figure out the equation of the plane described (...) (24 years ago, 11-Sep-00, to lugnet.cad)
| | | | | | | | | | | | RE: need Help finding a co-ordinate —Bram Lambrecht
| | | | | (...) And in case you don't have a text handy... lets call our points A=(a1,a2,a3), B, and C. Find the cross product of AB x AC = N = <n1,n2,n3> to get the normal vector to the plane. Then n1(x-a1) + n2(y-a2) + n3(z-a3) = 0 is the equation of the (...) (24 years ago, 11-Sep-00, to lugnet.cad)
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