   plane (x, y, z) and d from 3 vertexes
  how do i get a plane equation in x, y, z and d from 3 vectors. thanks  
  Do you mean from three points?To find a plane through p1, p2 and p3, calculate v1 = (p2 - p1) and v2 = (p3 - p2). Take the cross product of v1 and v2 and call it N. N is orthogonal to the plane, and gives you the values of a, b and c. Now you can solve for d, and you''re done.  ;  i''ve got the normal already, but i don''t know how to get d. is it just the average of the three points and then the distance to the origin?  ;  Hi!v1 = p2 - p1v2 = p3 - p1D = (v1 x v2) dot product p1Ax + By + Cz = Dv1 = p2 - p1v2 = p3 - p2is ok to.[edited by - axodoss on August 20, 2002 4:11:33 AM];  You can calculate d like this:d = -(ax + by + cz)For the values of x, y and z, use one of the points you started with.  ;  n = ||(b - a)x(c - a)||d = n . aWhere n = the normal of the plane. (a, b, c) in other words.  ;  so, do all these methods work? beer hunter''s looks fast and simple, but i''ve found the fast and simple almost never works  i''ll try it tho  ;  The other guys said to use the dot product; I just wrote the dot product out in longhand.I also negated the result of the dot product while the others didn''t. I was thinking of the equation as ax + by + cz + d = 0.  ;  i''ve seen that euqation around, ax + by + cz + d = 0, and i guess i should have known to solve for d lol.  