I do not understand. Since this is executed in a loop, for the circle it looks l...

orlp · on Feb 9, 2015

In the original version it's possible that a penetrating object gets drawn, in the modified version penetrating objects are always resolved before the drawing happens.

sago · on Feb 9, 2015

(Edit: I can be clearer, using your approach - more verbose explanation trimmed)

In the linked version we are doing

... move, draw, de-overlap, move, draw, de-overlap ...

So the move might cause an overlap, which we'd draw on screen. Having objects routinely interpenetrating a little (by a frame's worth) can appear springy, as if they aren't made of rigid material.

Better would be

... move, de-overlap, draw, move, de-overlap, draw ...