How do I keep a Plane aligned to 3 Point Helpers?

MAXScript Frequently Asked Questions

A user asked:

I have 3 Point Helpers which determines a plane in 3d space and I animated all of them randomly.

How can I keep a Plane object always oriented exactly to the plane determined by the Points?

Answer:

This is a good place to use a Transform Script controller.

• Create 3 Point Helpers - Point01, Point02 and Point03

• Create a Plane primitive.

• Go to Motion tab, select the Transform controller track, assign Transform Script

Enter the following Script:

dependsOn $Point01.pos.controller --update when Point01 moves

dependsOn $Point02.pos.controller --update when Point02 moves

dependsOn $Point03.pos.controller --update when Point03 moves

p1 = $Point01.pos --the position of Point01

p2 = $Point02.pos --the position of Point02

p3 = $Point03.pos --the position of Point03

v1 = normalize (p2-p1) --the vector from Point01 to Point02

v2 = normalize (p3-p1) --the vector from Point01 to Point03

nv1 = cross v1 v2 --the cross product, the normal to the plane

nv2 = cross nv1 v1 --the cross product of the normal and vector 1

--Create a matrix3 value using he first vector, the vector perpendicular

--to it and the normal to the plane and the normal vector itself.

--The translation part (.row4 which is the position) is the middle point

--of the 3 points' positions:

matrix3 v1 nv2 nv1 ((p1+p2+p3)/3)

• Move / animate the points - the Plane should follow.

See also

Frequently Asked Questions