117 lines
3.3 KiB
GDScript
117 lines
3.3 KiB
GDScript
@tool
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@icon("parallel_state.svg")
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## A parallel state is a state which can have sub-states, all of which are active
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## when the parallel state is active.
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class_name ParallelState
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extends State
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# all children of the state
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var _sub_states:Array[State] = []
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func _state_init():
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super._state_init()
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# find all children of this state which are states
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for child in get_children():
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if child is State:
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_sub_states.append(child)
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child._state_init()
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# since there is no state transitions between parallel states, we don't need to
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# subscribe to events from our children
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func _handle_transition(transition:Transition, source:State):
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# resolve the target state
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var target = transition.resolve_target()
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if not target is State:
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push_error("The target state '" + str(transition.to) + "' of the transition from '" + source.name + "' is not a state.")
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return
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# the target state can be
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# 0. this state. in this case just activate the state and all its children.
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# this can happen when a child state transfers back to its parent state.
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# 1. a direct child of this state. this is the easy case in which
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# we will do nothing, because our direct children are always active.
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# 2. a descendant of this state. in this case we find the direct child which
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# is the ancestor of the target state and then ask it to perform
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# the transition.
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# 3. no descendant of this state. in this case, we ask our parent state to
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# perform the transition
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if target == self:
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# exit this state
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_state_exit()
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# then re-enter it
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_state_enter(false)
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return
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if target in get_children():
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# all good, nothing to do.
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return
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if self.is_ancestor_of(target):
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# find the child which is the ancestor of the new target.
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for child in get_children():
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if child is State and child.is_ancestor_of(target):
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# ask child to handle the transition
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child._handle_transition(transition, source)
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return
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return
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# ask the parent
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get_parent()._handle_transition(transition, source)
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func _state_enter(expect_transition:bool = false):
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super._state_enter()
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# enter all children
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for child in _sub_states:
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child._state_enter()
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func _state_exit():
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# exit all children
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for child in _sub_states:
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child._state_exit()
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super._state_exit()
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func _state_step():
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super._state_step()
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for child in _sub_states:
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child._state_step()
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func _process_transitions(event:StringName, property_change:bool = false) -> bool:
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if not active:
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return false
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# forward to all children
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var handled := false
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for child in _sub_states:
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var child_handled_it = child._process_transitions(event, property_change)
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handled = handled or child_handled_it
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# if any child handled this, we don't touch it anymore
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if handled:
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# emit the event_received signal for completeness
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# unless it was a property change
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if not property_change:
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self.event_received.emit(event)
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return true
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# otherwise handle it ourselves
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# defer to the base class
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return super._process_transitions(event, property_change)
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func _get_configuration_warnings() -> PackedStringArray:
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var warnings = super._get_configuration_warnings()
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var child_count = 0
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for child in get_children():
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if child is State:
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child_count += 1
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if child_count < 2:
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warnings.append("Parallel states should have at least two child states.")
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return warnings
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