broken_seals_2ds/game/steering_ai_framework/GSAIPath.gd
2022-01-30 23:20:50 +01:00

133 lines
3.7 KiB
GDScript

# Represents a path made up of Vector3 waypoints, split into segments path
# follow behaviors can use.
class_name GSAIPath
extends Reference
# If `false`, the path loops.
var is_open: bool
# Total length of the path.
var length: float
var _segments: Array
var _nearest_point_on_segment: Vector3
var _nearest_point_on_path: Vector3
func _init(waypoints: Array, _is_open := false) -> void:
self.is_open = _is_open
create_path(waypoints)
_nearest_point_on_segment = waypoints[0]
_nearest_point_on_path = waypoints[0]
# Creates a path from a list of waypoints.
func create_path(waypoints: Array) -> void:
if not waypoints or waypoints.size() < 2:
printerr("Waypoints cannot be null and must contain at least two (2) waypoints.")
return
_segments = []
length = 0
var current: Vector3 = waypoints.front()
var previous: Vector3
for i in range(1, waypoints.size(), 1):
previous = current
if i < waypoints.size():
current = waypoints[i]
elif is_open:
break
else:
current = waypoints[0]
var segment := GSAISegment.new(previous, current)
length += segment.length
segment.cumulative_length = length
_segments.append(segment)
# Returns the distance from `agent_current_position` to the next waypoint.
func calculate_distance(agent_current_position: Vector3) -> float:
if _segments.size() == 0:
return 0.0
var smallest_distance_squared: float = INF
var nearest_segment: GSAISegment
for i in range(_segments.size()):
var segment: GSAISegment = _segments[i]
var distance_squared := _calculate_point_segment_distance_squared(
segment.begin, segment.end, agent_current_position
)
if distance_squared < smallest_distance_squared:
_nearest_point_on_path = _nearest_point_on_segment
smallest_distance_squared = distance_squared
nearest_segment = segment
var length_on_path := (
nearest_segment.cumulative_length
- _nearest_point_on_path.distance_to(nearest_segment.end)
)
return length_on_path
# Calculates a target position from the path's starting point based on the `target_distance`.
func calculate_target_position(target_distance: float) -> Vector3:
if is_open:
target_distance = clamp(target_distance, 0, length)
else:
if target_distance < 0:
target_distance = length + fmod(target_distance, length)
elif target_distance > length:
target_distance = fmod(target_distance, length)
var desired_segment: GSAISegment
for i in range(_segments.size()):
var segment: GSAISegment = _segments[i]
if segment.cumulative_length >= target_distance:
desired_segment = segment
break
if not desired_segment:
desired_segment = _segments.back()
var distance := desired_segment.cumulative_length - target_distance
return (
((desired_segment.begin - desired_segment.end) * (distance / desired_segment.length))
+ desired_segment.end
)
# Returns the position of the first point on the path.
func get_start_point() -> Vector3:
return _segments.front().begin
# Returns the position of the last point on the path.
func get_end_point() -> Vector3:
return _segments.back().end
func _calculate_point_segment_distance_squared(start: Vector3, end: Vector3, position: Vector3) -> float:
_nearest_point_on_segment = start
var start_end := end - start
var start_end_length_squared := start_end.length_squared()
if start_end_length_squared != 0:
var t = (position - start).dot(start_end) / start_end_length_squared
_nearest_point_on_segment += start_end * clamp(t, 0, 1)
return _nearest_point_on_segment.distance_squared_to(position)
class GSAISegment:
var begin: Vector3
var end: Vector3
var length: float
var cumulative_length: float
func _init(_begin: Vector3, _end: Vector3) -> void:
self.begin = _begin
self.end = _end
length = _begin.distance_to(_end)