Finding coordinates of a point between two points?

Question

Doing some 3D stuff in wpf- want to use a simpler test to see if everything is working (before moving to curves).

The basic question is given two points x1,y1,z1 and

Answer 1

This has to do with math, but ok. Let P and Q be the two given points and X the point you're looking for.

P + r(Q - P) = X

r indicates a factor.

if 0 < r < 1: the point x will be on the line between the two points.

That's it!

EDIT:

To find a point at a given distance d from P(p1/p2/p3):

d² / euclidian_square_distance(P,Q) = r

Insert r in the equation mentioned above and you'll have your point! :)

P.S: Btw: P-Q = (Px - Qx, Py - Qy, Pz - Qz)... i bet you alread knew it :)