2D transformation I have a math problem for some code I am writing. I don't have much 
experience with 2D transformations, but I am sure there must be a 
straight-froward formula for my problem. 
I have illustrated it here:
 
My goal is to work out the co-ordinates of (Xp2, Yp2). 
Shape A is a quadrilateral that exists that can exist anywhere in 2D 
space. Its four co-ordinates are known. It contains a point (Xp1, 
Yp1), which are also known. 
Shape B is a rectangle with one corner at (0,0). The height and width 
are variable, but known. 
Shape A needs to be transposed to Shape B so that the new position of 
the point inside can be calculated. 
How do I work out the new co-ordinates of (Xp2, Yp2)?
Cheers,

See my answer to "Tranforming 2D outline into 3D plane". The transforms and 4 point to 4 point mapping described there should be just what you need.
