Collision and click detection

By bbox. PytchActorInstance has bounding_box() method.

‘Touching’ is done via bbox overlap. Non-shown instances never touch anything.

Exposed to Pytch as a method on Sprite: self.touching(), underneath is instance_is_touching_any_of() on Project — has to be Project because Project knows what instances are registered of the given class.

Clicking on Sprite / Stage

Done via bbox. Check each Sprite ‘from front to back’ as per the “drawing layers”. The Stage should always be hit if nothing else is. Launch “clicked” event on particular instance. Can be more than one click-handler.

Similar to ‘on-clone’ in that threads run on one particular object, not all of class.

Mouse clicks drained at the start of one-frame and processed (see “Mouse” section of the “environment” docs).