Covered area of convex/concave shape

BlitzMax Forums/BlitzMax Programming/Covered area of convex/concave shape

Snixx(Posted 2009) [#1]
How can I return a percentage of area covered? It's a tricky beast. The convex or concave 2d shape would be covered by rects of various sizes only. Any math genius able to assist please?


ImaginaryHuman(Posted 2009) [#2]
Go through all the rectangles and add up rectwidth*rectheight to get a total?


Ryan Burnside(Posted 2009) [#3]
Hmm perhaps it would be best to triangulate the shape then find the sum of each triangles area. You want to turn your concave shape into convex triangles I think. If I recall any shape can be broken down into triangles and the area of a triangle is simply 1/2 base * height.

You can get the formula here.
http://www.mathgoodies.com/lessons/vol1/area_triangle.html

Sadly I don't know how the best way to dynamically make triangles from a concave shape.


Snixx(Posted 2009) [#4]
I probally didnt explain it very well.

Imagine a drawing on the floor, a shape such as a star made from 2d points.

Now take a small block and place it on the shape.

What area of the star is covered. (brain explodes)


TaskMaster(Posted 2009) [#5]
Break it into triangles, figure their dimensions, and do the math...

Do you have specific sizes for the problem?