87 lines
2.6 KiB
GDScript3
87 lines
2.6 KiB
GDScript3
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@tool
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@icon("transition.svg")
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class_name Transition
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extends Node
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## Fired when this transition is taken. For delayed transitions, this signal
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## will be fired when the transition is actually executed (e.g. when its delay
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## has elapsed and the transition has not been arborted before). The signal will
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## always be fired before the state is exited.
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signal taken()
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## The target state to which the transition should switch
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@export_node_path("State") var to:NodePath:
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set(value):
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to = value
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update_configuration_warnings()
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## The event that should trigger this transition, can be empty in which case
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## the transition will immediately be tried when the state is entered
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@export var event:StringName = "":
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set(value):
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event = value
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update_configuration_warnings()
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## An expression that must evaluate to true for the transition to be taken. Can be
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## empty in which case the transition will always be taken
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@export var guard:Guard:
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set(value):
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guard = value
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update_configuration_warnings()
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## A delay in seconds before the transition is taken. Can be 0 in which case
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## the transition will be taken immediately. The transition will only be taken
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## if the state is still active when the delay has passed and has never been left.
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@export var delay_seconds:float = 0.0:
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set(value):
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delay_seconds = value
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update_configuration_warnings()
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## Read-only property that returns true if the transition has an event specified.
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var has_event:bool:
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get:
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return event != null and event.length() > 0
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## Evaluates the guard expression and returns true if the transition should be taken.
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## If no guard expression is specified, this function will always return true.
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func evaluate_guard() -> bool:
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if guard == null:
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return true
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var parent_state = get_parent()
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if parent_state == null or not (parent_state is State):
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push_error("Transitions must be children of states.")
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return false
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return guard.is_satisfied(self, get_parent())
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## Resolves the target state and returns it. If the target state is not found,
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## this function will return null.
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func resolve_target() -> State:
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if to == null or to.is_empty():
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return null
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var result = get_node_or_null(to)
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if result is State:
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return result
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return null
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func _get_configuration_warnings():
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var warnings = []
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if get_child_count() > 0:
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warnings.append("Transitions should not have children")
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if to == null or to.is_empty():
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warnings.append("The target state is not set")
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elif resolve_target() == null:
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warnings.append("The target state " + str(to) + " could not be found")
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if not (get_parent() is State):
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warnings.append("Transitions must be children of states.")
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return warnings
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