Question re line length

[BrianBorg]

I have 2 points (lets say p1 and p2) that are 200.5m apart. How can I modify the points to be 200m exactly away. I just need the algorithm.

bramu

[DominiqueBroux]

Something simple like:

double ratio = 200/200.5;     
p2.X = p1.X + ratio * (p2.X-p1.X);
p2.Y = p1.Y + ratio * (p2.Y-p1.Y);
 

or do you need to deal with geodesic precision?