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aaronfrankeaaronfranke
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Add OMI_physics_gravity implementation and test files
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‎README.md

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Original file line numberDiff line numberDiff line change
@@ -8,6 +8,7 @@ Extensions implemented in this repository:
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| Extension name | Import | Export | Godot version | Link |
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| ------------------------------ | ------ | ------ | ------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
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| **OMI_physics_gravity** | Yes | Yes | 4.5+ | [OMI_physics_gravity extension spec](https://github.com/omigroup/gltf-extensions/tree/main/extensions/2.0/OMI_physics_gravity) |
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| **OMI_physics_joint** | Yes | Yes | 4.1+ | [OMI_physics_joint extension spec](https://github.com/omigroup/gltf-extensions/tree/main/extensions/2.0/OMI_physics_joint) |
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| **OMI_seat** | Yes | Yes | 4.0+ | [OMI_seat extension spec](https://github.com/omigroup/gltf-extensions/tree/main/extensions/2.0/OMI_seat) |
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| **OMI_spawn_point** | Yes | No | 4.0+ | [OMI_spawn_point extension spec](https://github.com/omigroup/gltf-extensions/tree/main/extensions/2.0/OMI_spawn_point) |

‎addons/omi_extensions/omi_extensions_plugin.gd

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@@ -13,6 +13,8 @@ func _enter_tree() -> void:
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GLTFDocument.register_gltf_document_extension(ext, true)
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ext = GLTFDocumentExtensionOMISpawnPoint.new()
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GLTFDocument.register_gltf_document_extension(ext)
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ext = GLTFDocumentExtensionOMIPhysicsGravity.new()
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GLTFDocument.register_gltf_document_extension(ext, true)
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ext = GLTFDocumentExtensionOMIPhysicsJoint.new()
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GLTFDocument.register_gltf_document_extension(ext)
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ext = GLTFDocumentExtensionOMIVehicle.new()

‎addons/omi_extensions/physics_gravity/custom_gravity_area.gd

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@@ -0,0 +1,312 @@
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@tool
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class_name CustomGravityArea3D
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extends Area3D
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enum CustomGravityType {
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DIRECTIONAL, ## Gravity in a direction in local space.
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POINT, ## Gravity towards the local origin point.
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DISC, ## Gravity towards a filled circle on the local XZ plane.
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TORUS, ## Gravity towards a hollow circle on the local XZ plane.
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LINE, ## Gravity towards a line defined by points in local space.
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SHAPED, ## Gravity towards a shape in local space.
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}
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@export var custom_gravity_type: CustomGravityType:
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set(value):
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custom_gravity_type = value
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notify_property_list_changed()
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var direction := Vector3.DOWN
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var radius: float = 1.0
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var line_points: PackedVector3Array
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var shape: Shape3D
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func _ready() -> void:
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if gravity_space_override == SPACE_OVERRIDE_DISABLED:
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push_warning("CustomGravityArea3D has its Area3D gravity override disabled, this node will not have gravity.")
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if gravity_type != GRAVITY_TYPE_TARGET:
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push_warning("CustomGravityArea3D has its Area3D gravity type not set to target. The CustomGravityArea3D gravity logic will not be used.")
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func _calculate_gravity_target(local_position: Vector3) -> Vector3:
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match custom_gravity_type:
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CustomGravityType.DIRECTIONAL:
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return local_position + direction
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CustomGravityType.POINT:
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return Vector3.ZERO
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CustomGravityType.DISC:
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var flat_position = Vector3(local_position.x, 0.0, local_position.z)
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return flat_position.limit_length(radius)
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CustomGravityType.TORUS:
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var flat_position = Vector3(local_position.x, 0.0, local_position.z)
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return flat_position.normalized() * radius
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CustomGravityType.LINE:
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var closest_point := Vector3.ZERO
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var closest_distance_sq: float = INF
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for i in range(line_points.size() - 1):
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var a: Vector3 = line_points[i]
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var b: Vector3 = line_points[i + 1]
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var closest: Vector3 = Geometry3D.get_closest_point_to_segment(local_position, a, b)
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var distance_sq: float = local_position.distance_squared_to(closest)
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if distance_sq < closest_distance_sq:
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closest_point = closest
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closest_distance_sq = distance_sq
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return closest_point
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CustomGravityType.SHAPED:
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return _get_closest_point_on_shape(shape, local_position)
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return Vector3()
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static func _project_point_onto_triangle(point: Vector3, a: Vector3, b: Vector3, c: Vector3) -> Vector3:
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var plane: Plane = Plane(a, b, c)
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var projected: Vector3 = plane.project(point)
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var bary: Vector3 = Geometry3D.get_triangle_barycentric_coords(projected, a, b, c)
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if 0.0 < bary.x and bary.x < 1.0 and 0.0 < bary.y and bary.y < 1.0 and 0.0 < bary.z and bary.z < 1.0:
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return projected # If all barycentric coordinates are between 0 and 1, this is on the triangle.
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# Else, find which two barycentric coordinates are the greatest, and project onto that line segment.
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if bary.x < bary.y and bary.x < bary.z:
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return Geometry3D.get_closest_point_to_segment(projected, b, c)
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if bary.y < bary.x and bary.y < bary.z:
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return Geometry3D.get_closest_point_to_segment(projected, a, c)
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return Geometry3D.get_closest_point_to_segment(projected, a, b)
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static func _get_closest_point_on_shape(shape: Shape3D, point: Vector3) -> Vector3:
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if shape is BoxShape3D:
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var extents = shape.size * 0.5
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return point.clamp(-extents, extents)
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if shape is SphereShape3D:
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return point.limit_length(shape.radius)
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if shape is CapsuleShape3D:
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var mid_extent: float = (shape.height - shape.radius * 2.0) * 0.5
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var projected: Vector3 = Geometry3D.get_closest_point_to_segment(point, Vector3(0.0, -mid_extent, 0.0), Vector3(0.0, mid_extent, 0.0))
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var difference: Vector3 = (point - projected).limit_length(shape.radius)
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return projected + difference
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if shape is CylinderShape3D:
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var extent: float = shape.height * 0.5
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var projected: Vector3 = Geometry3D.get_closest_point_to_segment(point, Vector3(0.0, -extent, 0.0), Vector3(0.0, extent, 0.0))
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var flat_location = Vector3(point.x, 0.0, point.z)
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return projected + flat_location.limit_length(shape.radius)
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if shape is ConcavePolygonShape3D:
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var closest_point := Vector3.ZERO
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var closest_distance_sq: float = INF
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var faces: PackedVector3Array = shape.get_faces()
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for i in range(0, faces.size(), 3):
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var on_triangle: Vector3 = _project_point_onto_triangle(point, faces[i], faces[i + 1], faces[i + 2])
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var distance_sq: float = point.distance_squared_to(on_triangle)
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if distance_sq < closest_distance_sq:
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closest_point = on_triangle
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closest_distance_sq = distance_sq
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return closest_point
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printerr("Unsupported shape: ", shape)
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return point
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func _get_property_list() -> Array[Dictionary]:
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var properties: Array[Dictionary] = []
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match custom_gravity_type:
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CustomGravityType.DIRECTIONAL:
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properties.append({
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"name": "direction",
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"type": TYPE_VECTOR3,
114+
"usage": PROPERTY_USAGE_DEFAULT,
115+
})
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CustomGravityType.DISC, CustomGravityType.TORUS:
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properties.append({
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"name": "radius",
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"type": TYPE_FLOAT,
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"usage": PROPERTY_USAGE_DEFAULT,
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})
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CustomGravityType.LINE:
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properties.append({
124+
"name": "line_points",
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"type": TYPE_PACKED_VECTOR3_ARRAY,
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"usage": PROPERTY_USAGE_DEFAULT,
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})
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CustomGravityType.SHAPED:
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properties.append({
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"name": "shape",
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"type": TYPE_OBJECT,
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"usage": PROPERTY_USAGE_DEFAULT,
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"hint": PROPERTY_HINT_RESOURCE_TYPE,
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"hint_string": "Shape3D"
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})
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return properties
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# Everything below this point is for GLTF serialization.
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func _get_or_create_state_shapes_in_state(gltf_state: GLTFState) -> Array:
141+
var state_extensions: Dictionary = gltf_state.json.get_or_add("extensions", {})
142+
if not state_extensions.has("OMI_physics_shape"):
143+
state_extensions["OMI_physics_shape"] = {}
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gltf_state.add_used_extension("OMI_physics_shape", false)
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var omi_physics_shape_ext: Dictionary = state_extensions["OMI_physics_shape"]
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var state_shapes: Array = omi_physics_shape_ext.get_or_add("shapes", [])
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return state_shapes
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149+
150+
func to_dictionary(gltf_state: GLTFState) -> Dictionary:
151+
var ret: Dictionary = area_gravity_to_dictionary(self)
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if gravity_type != Area3D.GravityType.GRAVITY_TYPE_TARGET:
153+
return ret
154+
var type_string: String = _gravity_type_enum_to_string(custom_gravity_type)
155+
ret["type"] = type_string
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var sub_dict: Dictionary = {}
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if custom_gravity_type == CustomGravityType.DIRECTIONAL:
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if not direction.is_equal_approx(Vector3.DOWN):
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sub_dict = { "direction": [direction.x, direction.y, direction.z] }
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else:
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if gravity_point_unit_distance != 0.0:
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sub_dict = { "unitDistance": gravity_point_unit_distance }
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match custom_gravity_type:
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CustomGravityType.DISC, CustomGravityType.TORUS:
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if radius != 1.0:
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sub_dict["radius"] = radius
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CustomGravityType.LINE:
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var point_numbers: Array = []
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for line_point in line_points:
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point_numbers.append(line_point.x)
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point_numbers.append(line_point.y)
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point_numbers.append(line_point.z)
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sub_dict["points"] = point_numbers
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CustomGravityType.SHAPED:
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var state_shapes: Array = _get_or_create_state_shapes_in_state(gltf_state)
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var gltf_shape := GLTFPhysicsShape.from_resource(shape)
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sub_dict["shape"] = state_shapes.size()
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state_shapes.append(gltf_shape.to_dictionary())
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if not sub_dict.is_empty():
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ret[type_string] = sub_dict
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return ret
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## Functionality common to all Godot Area3D nodes including non-CustomGravityArea3D nodes.
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static func area_gravity_to_dictionary(area: Area3D) -> Dictionary:
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var ret: Dictionary = {}
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var space_override: Area3D.SpaceOverride = area.gravity_space_override
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if space_override == Area3D.SpaceOverride.SPACE_OVERRIDE_DISABLED:
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return ret
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ret["gravity"] = area.gravity
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if area.priority != 0:
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ret["priority"] = area.priority
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if space_override == Area3D.SpaceOverride.SPACE_OVERRIDE_REPLACE:
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ret["replace"] = true
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ret["stop"] = true
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elif space_override == Area3D.SpaceOverride.SPACE_OVERRIDE_COMBINE_REPLACE:
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ret["stop"] = true
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elif space_override == Area3D.SpaceOverride.SPACE_OVERRIDE_REPLACE_COMBINE:
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ret["replace"] = true
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if area.gravity_type == Area3D.GravityType.GRAVITY_TYPE_DIRECTIONAL:
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var dir: Vector3 = area.gravity_direction * area.global_basis.orthonormalized()
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if not dir.is_equal_approx(Vector3.DOWN):
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ret["directional"] = { "direction": [dir.x, dir.y, dir.z] }
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ret["type"] = "directional"
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elif area.gravity_type == Area3D.GravityType.GRAVITY_TYPE_POINT:
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var unit_dist: float = area.gravity_point_unit_distance
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if unit_dist != 0.0:
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ret["point"] = { "unitDistance": unit_dist }
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ret["type"] = "point"
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return ret
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static func from_dictionary(dict: Dictionary, gltf_state: GLTFState) -> CustomGravityArea3D:
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if "type" not in dict:
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printerr('GLTF gravity import: Missing required field "type", expected "directional", "point", "disc", "torus", "line", or "shaped".')
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return null
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if "gravity" not in dict:
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printerr('GLTF gravity import: Missing required field "gravity", expected a number in meters per second squared.')
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return null
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var type_string = dict.get("type")
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if type_string not in ["directional", "point", "disc", "torus", "line", "shaped"]:
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printerr("GLTF gravity import: Invalid gravity type, found: ", dict.get("type"), ' but expected "directional", "point", "disc", "torus", "line", or "shaped".')
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return null
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var gravity_amount = dict.get("gravity")
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if not gravity_amount is float: # All JSON numbers are floats.
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printerr("GLTF gravity import: Invalid gravity, found: ", dict.get("gravity"), ' but expected a number.')
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return null
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var ret: CustomGravityArea3D = CustomGravityArea3D.new()
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ret.gravity_type = Area3D.GRAVITY_TYPE_TARGET
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ret.custom_gravity_type = _gravity_type_string_to_enum(type_string)
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ret.gravity = gravity_amount
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var priority = dict.get("priority")
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if priority is float: # All JSON numbers are floats.
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ret.priority = priority
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var replace: bool = dict.get("replace", false)
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var stop: bool = dict.get("stop", false)
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if replace and stop:
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ret.gravity_space_override = Area3D.SpaceOverride.SPACE_OVERRIDE_REPLACE
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elif stop:
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ret.gravity_space_override = Area3D.SpaceOverride.SPACE_OVERRIDE_COMBINE_REPLACE
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elif replace:
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ret.gravity_space_override = Area3D.SpaceOverride.SPACE_OVERRIDE_REPLACE_COMBINE
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else:
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ret.gravity_space_override = Area3D.SpaceOverride.SPACE_OVERRIDE_COMBINE
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var sub_dict = dict.get(type_string)
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if not sub_dict is Dictionary:
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return ret
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var direction = sub_dict.get("direction")
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if direction is Array:
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ret.direction = Vector3(direction[0], direction[1], direction[2])
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var unit_distance = sub_dict.get("unitDistance")
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if unit_distance is float:
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ret.gravity_point_unit_distance = unit_distance
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var radius = sub_dict.get("radius")
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if radius is float:
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ret.radius = radius
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var points = sub_dict.get("points")
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if points is Array:
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var packed_points := PackedVector3Array()
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for i in range(0, points.size(), 3):
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packed_points.append(Vector3(points[i], points[i + 1], points[i + 2]))
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ret.line_points = packed_points
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var shape = sub_dict.get("shape")
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if shape is float: # Integer but all JSON numbers are floats.
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var shape_index: int = shape
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if shape_index < 0:
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printerr("GLTF gravity import: Invalid shape index, found: ", shape, " but expected a non-negative integer.")
268+
return ret
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var state_shapes: Array = gltf_state.get_additional_data(&"GLTFPhysicsShapes")
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if shape_index >= state_shapes.size():
271+
printerr("GLTF gravity import: Shape index ", shape_index, " is out of bounds (size=", state_shapes.size(), ").")
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return ret
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var gltf_shape: GLTFPhysicsShape = state_shapes[shape_index]
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ret.shape = gltf_shape.to_resource(true)
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return ret
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static func _gravity_type_enum_to_string(type: CustomGravityType) -> String:
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# The type value may be set to `"directional"`, `"point"`, `"disc"`, `"torus"`, `"line"`, or `"shaped"`.
280+
match type:
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CustomGravityType.DIRECTIONAL:
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return "directional"
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CustomGravityType.POINT:
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return "point"
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CustomGravityType.DISC:
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return "disc"
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CustomGravityType.TORUS:
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return "torus"
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CustomGravityType.LINE:
290+
return "line"
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CustomGravityType.SHAPED:
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return "shaped"
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assert(false, "GLTF gravity export: Invalid gravity type.")
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return ""
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static func _gravity_type_string_to_enum(type: String) -> CustomGravityType:
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match type:
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"directional":
300+
return CustomGravityType.DIRECTIONAL
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"point":
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return CustomGravityType.POINT
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"disc":
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return CustomGravityType.DISC
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"torus":
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return CustomGravityType.TORUS
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"line":
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return CustomGravityType.LINE
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"shaped":
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return CustomGravityType.SHAPED
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printerr("GLTF gravity import: Unknown gravity type: ", type)
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return CustomGravityType.DIRECTIONAL

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