def __is_dirty(self, entity, viewport, others=set()):
on_screen = collide(
entity.present().r_box(),
viewport)
was_on_screen = collide(
entity.past().r_box(),
viewport)
# Thing that are and were on screen have quite a couple of rules...
if on_screen and was_on_screen:
# Is the stretegy being suppresed?
if self.__force_all:
return True
# Force the drawing of new Entities first time they apppear on
# screen
if not self.__was_drawn(entity):
self.__mark_drawn(entity)
return True
# See if a redraw is necessary due to changes in the entity itentity
moved = entity.present().r_box() != entity.past().r_box()
sprite_changed = \
entity.present().state_name() != entity.past().state_name()
if moved or sprite_changed:
return True
# See if a redraw is necessary due to changes around the entity
for other in others:
collided = collide(
entity.past().r_box(),
other.past().r_box())
collide_now = collide(
entity.present().r_box(),
other.present().r_box())
if collided or collide_now:
return True
# Entities that change their onscreen status are dirty
elif on_screen != was_on_screen:
return True
return False
def render(self, stage, engine, viewport):
for entity in stage:
if collide(entity.present().r_box(), viewport):
entity.draw(engine, viewport)
