Efficiently getting isometric grid positions within a bounding box

Question

I have an isometric grid system who\'s coordinates start from [0,0] in the left hand corner of t

Answer 1

I think Aleksander has a very good idea on how to solve your problem.

Here is an alternative:

An easy way to reduce the number of grid squares to check is to find the coordinates of the corners of the blue box in grid coords. In your example you would only need to check the squares where 1.

alvaro gives a short and concise answer on how to check if a point is inside a box.