That said, would it not be easy enough for you to allow the use of both coordinate systems, with option (b) done by setting the vl_unit_size_pixels to 1.0?
I do actually have that option in now - there's two functions; one to transform to pixel coords (for rendering), and another to tranform to world coords. I'm currently just transforming to world coords for line-to-line intersection checks etc. - it's a tad faster as it removes the multiplication by vl_unit_size_pixels. This is where the error creeps in but, as I've said, using the screen transformation instead still isn't perfect. :) Only thing worse then not being able to do something that looks obvious is having someone else able to do something that looks impossible.
Whichever way I handle this, it'll be consistent so I shouldn't have any problems in that regard. :) I would use A in all situations.
I'm beginning to think that. There doesn't seem a way to get the best of both worlds so I think I should just stick with what I have now. I'm just having trouble making decisions today. :PThanks all for the input!