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# Physics-collision-based navigation grid, a quick and simple alternative for navigation polygons. |
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# Part of "Xenomusa" (C) Mara Huldra 2022 |
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# SPDX-License-Identifier: MIT |
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extends Node2D |
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@export var tilemap: TileMap |
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@export var excludes: Array[CollisionObject2D] |
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@export_flags_2d_physics var nav_physics_layers: int = 1 |
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var update_nav_grid: bool = false |
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var nav_grid: AStarGrid2D |
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var nav_tile_size: Vector2 |
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func _ready() -> void: |
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queue_nav_grid_update() |
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func _partial_update(used_rect: Rect2i) -> void: |
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var space_state := get_world_2d().direct_space_state |
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# Collide with a circle (fastest). |
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var shape := CircleShape2D.new() |
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shape.radius = nav_tile_size.x / 2.0 |
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var parameters := PhysicsShapeQueryParameters2D.new() |
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parameters.collide_with_areas = true |
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parameters.collide_with_bodies = true |
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parameters.collision_mask = nav_physics_layers |
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parameters.shape = shape |
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var exclude_rids = [] |
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for obj in excludes: |
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exclude_rids.append(obj.get_rid()) |
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parameters.exclude = exclude_rids |
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for y in range(used_rect.position.y, used_rect.end.y): |
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for x in range(used_rect.position.x, used_rect.end.x): |
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var pos := Vector2i(x, y) |
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# Position shape in middle, edge, or corner of tile (2x "oversampling"). |
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parameters.transform.origin = Vector2(pos) * nav_tile_size |
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var collisions := space_state.collide_shape(parameters, 1) |
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var solid := collisions.size() > 0 |
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nav_grid.set_point_solid(pos, solid) |
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func _build_navigation_map() -> void: |
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print("Updating nav grid.") |
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nav_grid = AStarGrid2D.new() |
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if tilemap == null: |
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printerr("FoxNav: No tilemap installed") |
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return |
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# Tiles are twice the resolution of the tileset. |
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var used_rect: Rect2i = tilemap.get_used_rect() |
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used_rect.position *= 2 |
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used_rect.size *= 2 |
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nav_tile_size = Vector2(tilemap.tile_set.tile_size) / 2.0 |
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nav_grid.diagonal_mode = AStarGrid2D.DIAGONAL_MODE_ONLY_IF_NO_OBSTACLES |
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nav_grid.region = used_rect |
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nav_grid.update() |
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_partial_update(used_rect) |
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func queue_nav_grid_update() -> void: |
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# XXX needs a way to specify only a certain rectangle. |
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update_nav_grid = true |
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func navigate(source: Vector2, destination: Vector2) -> Array[Vector2]: |
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var source_id = Vector2i(round(source / nav_tile_size)) |
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var destination_id = Vector2i(round(destination / nav_tile_size)) |
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var ret_path: Array[Vector2] = [] |
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var first := true # Skip first item it will be the current cell center. |
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for id in nav_grid.get_id_path(source_id, destination_id): |
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if not first: |
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ret_path.append(Vector2(id) * nav_tile_size) |
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first = false |
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return ret_path |
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func _physics_process(_delta) -> void: |
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if update_nav_grid: # Must be done in physics process. |
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_build_navigation_map() |
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update_nav_grid = false |
