Suppose we have lots of

a. Find the extreme points (right-most, left-most, top, down).

b. Break the whole region in four parts.

c. Start rotating clock-wise or counter clock-wise from one extreme point to another using (y/x)=TAN(q) equation.

You can download full algorithm in Adobe Acrobat format from here.

Here is the Pascal source code and a sample data file.

Sample Execution Results