What is an Efficient algorithm to find Area of Overlapping Rectangles
- by namenlos
My situation
Input: a set of rectangles
each rect is comprised of 4 doubles like this: (x0,y0,x1,y1)
they are not "rotated" at any angle, all they are "normal" rectangles that go "up/down" and "left/right" with respect to the screen
they are randomly placed - they may be touching at the edges, overlapping , or not have any contact
I will have several hundred rectangles
this is implemented in C#
I need to find
The area that is formed by their overlap - all the area in the canvas that more than one rectangle "covers" (for example with two rectangles, it would be the intersection)
I don't need the geometry of the overlap - just the area (example: 4 sq inches)
Overlaps shouldn't be counted multiple times - so for example imagine 3 rects that have the same size and position - they are right on top of each other - this area should be counted once (not three times)
Example
The image below contains thre rectangles: A,B,C
A and B overlap (as indicated by dashes)
B and C overlap (as indicated by dashes)
What I am looking for is the area where the dashes are shown
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AAAAAAAAAAAAAAAA--------------BBB
AAAAAAAAAAAAAAAA--------------BBB
AAAAAAAAAAAAAAAA--------------BBB
AAAAAAAAAAAAAAAA--------------BBB
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BBBBBB-----------CCCCCCCC
BBBBBB-----------CCCCCCCC
BBBBBB-----------CCCCCCCC
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