I'm trying to calculate the total area all bodies or shapes are occupying on the screen. I.e. if I have 2 circles, A and B, that intersect each other, I want to calculate the area that A union B covers (on the screen).
I've been reading through the chipmunk documentation and looked in the chipmunk API for a method that I might use, but I haven't found anything that I can use directly.
The only two methods I found, that might be useful, are these two: pointQueryFirst:layers:group: and segmentQueryFirstFrom:to:layers:group:
The way I was thinking was to:
- Use the first method (pointQueryFirst) to go through all points on the screen and call this method. If a point doesn't have a shape in them, then accumulate it to a variable. Then divide that variable value with the area of the screen to get percentage of the screen that is free.
- Or use the second method (segmentQueryFirstFrom), create an recursive algorithm that divides the screen in half and run the query on each half, if any half contains a shape, then divide that area into halves and check if those contains any shapes, and so on...
But I expect that in using them, the overall performance will suffer. Is there another solution that I can use? Another method that I haven't found? Any help is greatly appreciated.
Chipmunk isn't particularly going to be able to help you with that. The methods you mentioned will work, but be ridiculously slow.
I think I would do a good old fashioned occlusion query. Render the shapes into a texture or some sort of offscreen buffer and then count the pixels.