Calculate shadow path & size + object size based on distance

[chubby92]

What are the variables I need to take in account if I want to calculate shadow path and size?
I will try to simplify my questions.

I have a 2d circle (radius: 28) which means the size of the circle (in box) is 56x56 at specific point (lets say 300,300).

I tell the 2d circle to go in specific path, let's say from 300,300 to 300,200.

I want to tell its shadow what path to do based on the 2d circle path.

ofcourse the size of the ball need to be calculated aswell..

I guess I need some extra variables because I am talking about 3d space in 2d.. (lets say the "sun" is always above the ball so u don't need to calculate its degrees from the "sun", only its distance)
I am pretty sure it's possible but I have no idea how to calculate and what extra variables I need...
Hopefully you understood what I want, if u didnt just tell me which part and I will try to re-explain or something.

Thanks

 

[UltrafastPED]

Start by reading upon on 3D projection techniques:
http://en.wikipedia.org/wiki/Perspective_transform

It helps to do some drawings; the method is geometric, but the implementation is algebraic!