Hi. I was just wondering if anyone could help me with a formula to solve the following problem. I have two locations (L1 and L2), which I know the cartesian coordinates of, situated in a three dimensional space. I also have a distance (D) which I also know the value of. D is not the distance between L1 and L2. If an object moves from it's starting location at L1 in a straight line towards L2, how do I calculate the cartesian coordinates of the object after it has travelled a distance of D units. I'd certainly appreciate any assistance in this. Cheers.