Patches occupied by turtle shape in NetLogo

Question

I would like a little bit of help with understanding and using patch shape and size vs origin. I am trying to mark the patches that are exactly under a specific turtle shape. For example, if the turtle is a rectangle of (w x h) I would like to change color or properties of all patches under that shape, not only at the origin patch. Of course, with a rectangle maybe I can manually color the patches under, but is there any option to modify patches under a more complicated turtle shape? Thank you.

Answer 1

Well there is a kludgey way to do this that has some artifacts of aliasing and other minor issues like transferring all visible objects (turtles, links, labels, drawing layer, etc) to the pcolor of a patch. But at least it's possible. It takes advantage of the included bitmap extension. Main idea is in paint-patches below.

extensions [bitmap]

to setup
  clear-all
  resize-world 0 199 0 199
  set-patch-size 1 
  ask n-of 30 patches [ sprout 1 [set size 15]]
end

to paint-patches
  let bmap bitmap:from-view
  bitmap:copy-to-pcolors bmap true
  ask turtles [ht] ; to show that the turtle shape is now painted to pcolors
end

Answer 2

That's impossible in NetLogo. Turtle shapes are purely visual. There's no way to access the exact contours of a turtle shape and then somehow use the contour as the basis for a computation.

If you're working with a small set of known shapes, like maybe square/triangle/circle, then you could handle each of the cases individually and write your own code to color patches corresponding to the shape. But if you need this capability in general, you're stuck.

You could write an extension to do it, but the extension would have to contain all original code to actually do the work of computing the overlap between the shape and the patch grid. There is no existing code inside NetLogo that does the computation you want.