Add support for XMP DCMI license data via KHR_xmp_json_ld (#8)

addons/gltf_khr_xmp_copyright/LICENSE

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+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <https://unlicense.org>

addons/gltf_khr_xmp_copyright/gltf_khr_xmp_plugin.gd

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+@tool
+extends EditorPlugin
+
+
+func _enter_tree() -> void:
+	# NOTE: Be sure to also instance and register these at runtime if you want
+	# the extensions at runtime. This editor plugin script won't run in games.
+	var ext = GLTFDocumentExtensionKHR_XMP.new()
+	GLTFDocument.register_gltf_document_extension(ext)

addons/gltf_khr_xmp_copyright/plugin.cfg

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+[plugin]
+
+name="glTF KHR_xmp_json_ld Copyright"
+description="Godot implementation of the glTF KHR_xmp_json_ld extension for DCMI copyright metadata. Requires Godot 4.3 or newer."
+author="Aaron Franke"
+version="4.3"
+script="gltf_khr_xmp_plugin.gd"

addons/gltf_khr_xmp_copyright/xmp/dcmi_license_metadata.gd

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+@tool
+## Stores DCMI XMP license info and metadata as defined by Khronos and DCMI.
+## List of elements: http://purl.org/dc/elements/1.1/
+## https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_xmp_json_ld
+class_name DCMILicenseMetadata
+extends XMPMetadataBase
+
+# TODO: On export: format
+
+const CONTEXT_URL: String = "http://purl.org/dc/elements/1.1/"
+
+@export_group("License")
+## License name. Examples: "MIT License", "CC BY-SA 4.0", "All Rights Reserved"
+@export_placeholder("Ex: MIT, BSD, CC0, etc") var rights: String = ""
+## Primary authors. Example: John Smith <jsmith@email.com>
+@export var creator: PackedStringArray = []
+## Secondary authors. Example: John Smith <jsmith@email.com>
+@export var contributor: PackedStringArray = []
+## Company names. Example: Smith Co.
+@export var publisher: PackedStringArray = []
+
+@export_group("Content")
+## Example: Rainbow Godette Model
+@export_placeholder("Name of this GLTF file") var title: String = ""
+## Example: Detailed Godette model with added sunshine, lollipops, and rainbows.
+@export_placeholder("Description of this GLTF file") var description: String = ""
+## Examples: Architecture, Automotive, Botany
+@export var subject: PackedStringArray = []
+## Examples: Character, Building, Vehicle, Plant, Prop
+@export var type: PackedStringArray = []
+
+@export_group("Locale")
+## Location. Example: Bay Area, CA, USA
+@export_placeholder("Location/area/city/country") var coverage: String = ""
+## Examples: 2014-02-09, 2014-02-09T22:10:30
+@export_placeholder("YYYY-MM-DD and/or hh:mm:ss") var date: String = ""
+## ISO 639-2 code (ex: en), ISO 639-3 code (ex: eng), or culture ID (ex: en_US).
+@export_placeholder("en, eng, en_US, etc") var language: String = ""
+
+@export_group("Reference")
+## Example: ISBN-13:978-0802144423
+@export_placeholder("DOI, ISBN, URN, etc") var identifier: String = ""
+## Example: https://your.website/file.glb
+@export_placeholder("URL to this GLTF on the web") var source: String = ""
+## Websites. Example: https://godotengine.org/
+@export var relation: PackedStringArray = []
+
+
+func to_dictionary() -> Dictionary:
+	var dcmi_dict: Dictionary = _dcmi_properties_to_dictionary()
+	if dcmi_dict.is_empty():
+		# If there was no data, don't add @context, just return an empty dict.
+		return dcmi_dict
+	var ret: Dictionary = {
+		"@context": {
+			"dc": "http://purl.org/dc/elements/1.1/",
+		},
+		"@id": "",
+	}
+	ret.merge(dcmi_dict)
+	return ret
+
+
+func _dcmi_properties_to_dictionary() -> Dictionary:
+	var dcmi_dict: Dictionary = {}
+	if not contributor.is_empty():
+		dcmi_dict["dc:contributor"] = { "@set": contributor }
+	if not coverage.is_empty():
+		dcmi_dict["dc:coverage"] = coverage
+	if not creator.is_empty():
+		dcmi_dict["dc:creator"] = { "@list": creator }
+	if not date.is_empty():
+		dcmi_dict["dc:date"] = date
+	if not description.is_empty():
+		dcmi_dict["dc:description"] = description
+	if not identifier.is_empty():
+		dcmi_dict["dc:identifier"] = identifier
+	if not language.is_empty():
+		dcmi_dict["dc:language"] = language
+	if not publisher.is_empty():
+		dcmi_dict["dc:publisher"] = { "@set": publisher }
+	if not relation.is_empty():
+		dcmi_dict["dc:relation"] = { "@set": relation }
+	if not rights.is_empty():
+		dcmi_dict["dc:rights"] = rights
+	if not source.is_empty():
+		dcmi_dict["dc:source"] = source
+	if not subject.is_empty():
+		dcmi_dict["dc:subject"] = { "@set": subject }
+	if not title.is_empty():
+		dcmi_dict["dc:title"] = title
+	if not type.is_empty():
+		dcmi_dict["dc:type"] = { "@set": type }
+	return dcmi_dict
+
+
+static func from_dictionary(xmp_packet: Dictionary) -> XMPMetadataBase:
+	var context_url: String = xmp_packet["@context"]["dc"]
+	if context_url != DCMILicenseMetadata.CONTEXT_URL:
+		push_warning("GLTF KHR XMP: DCMI metadata had a URL of '" + context_url + "' but expected '" + DCMILicenseMetadata.CONTEXT_URL + "'. Attempting to parse anyway.")
+	var ret := DCMILicenseMetadata.new()
+	ret.xmp_json_ld = xmp_packet
+	_dcmi_properties_from_dictionary(ret, xmp_packet)
+	return ret
+
+
+const _SINGLE_VALUES: PackedStringArray = ["coverage", "date", "description", "identifier", "language", "rights", "source", "title"]
+const _ARRAY_VALUES: PackedStringArray = ["contributor", "creator", "publisher", "relation", "subject", "type"]
+
+static func _dcmi_properties_from_dictionary(dcmi_data: DCMILicenseMetadata, xmp_packet: Dictionary) -> void:
+	for single_value_name in _SINGLE_VALUES:
+		var dcmi_prefixed: String = "dc:" + single_value_name
+		if xmp_packet.has(dcmi_prefixed):
+			var extracted = extract_single_value_from_json_ld(xmp_packet[dcmi_prefixed])
+			dcmi_data.set(single_value_name, String(extracted))
+	for array_value_name in _ARRAY_VALUES:
+		var dcmi_prefixed: String = "dc:" + array_value_name
+		if xmp_packet.has(dcmi_prefixed):
+			var extracted = extract_array_from_json_ld(xmp_packet[dcmi_prefixed])
+			dcmi_data.set(array_value_name, PackedStringArray(extracted))

addons/gltf_khr_xmp_copyright/xmp/khr_xmp_doc_ext.gd

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+@tool
+class_name GLTFDocumentExtensionKHR_XMP
+extends GLTFDocumentExtension
+
+
+## Applies to the whole document when exporting.
+@export var dcmi_license_metadata := DCMILicenseMetadata.new()
+
+
+# Import process.
+func _import_preflight(gltf_state: GLTFState, extensions_used: PackedStringArray) -> Error:
+	if not extensions_used.has("KHR_xmp_json_ld"):
+		return ERR_SKIP
+	var state_json: Dictionary = gltf_state.json
+	if not state_json.has("extensions"):
+		return ERR_INVALID_DATA
+	var doc_extensions: Dictionary = state_json["extensions"]
+	if not doc_extensions.has("KHR_xmp_json_ld"):
+		return ERR_INVALID_DATA
+	var khr_xmp_ext: Dictionary = doc_extensions["KHR_xmp_json_ld"]
+	if not khr_xmp_ext.has("packets"):
+		return ERR_INVALID_DATA
+	var khr_xmp_packets: Array = khr_xmp_ext["packets"]
+	var parsed_khr_xmp_data: Array = []
+	for xmp_packet in khr_xmp_packets:
+		var xmp: XMPMetadataBase = _parse_xmp_packet(gltf_state, xmp_packet)
+		if xmp == null:
+			return ERR_INVALID_DATA
+		parsed_khr_xmp_data.append(xmp)
+	gltf_state.set_additional_data(&"KHR_xmp_json_ld", parsed_khr_xmp_data)
+	return OK
+
+
+func _parse_xmp_packet(gltf_state: GLTFState, xmp_packet: Dictionary) -> XMPMetadataBase:
+	if not xmp_packet.has("@context"):
+		return null
+	var xmp_context: Dictionary = xmp_packet["@context"]
+	var xmp_metadata: XMPMetadataBase = null
+	for context_prefix in xmp_context:
+		if context_prefix == "dc":
+			xmp_metadata = DCMILicenseMetadata.from_dictionary(xmp_packet)
+		elif context_prefix == "rdf":
+			# RDF allows specifying language alternatives, it combines together
+			# with another context, we don't need to do anything special here.
+			pass
+		else:
+			# XMP is an open-ended standard, any data structure can be stored
+			# in it. Show a warning when we encounter something unrecognized,
+			# but the JSON data will still be available in an XMPMetadataBase.
+			push_warning("GLTF KHR XMP: Unrecognized context prefix '" + context_prefix + "'.")
+	if xmp_metadata == null:
+		# No specific class wants to handle this, so just return the base class.
+		xmp_metadata = XMPMetadataBase.from_dictionary(xmp_packet)
+	return xmp_metadata
+
+
+func _get_supported_extensions() -> PackedStringArray:
+	return PackedStringArray(["KHR_xmp_json_ld"])
+
+
+func _import_post(gltf_state: GLTFState, root: Node) -> Error:
+	var asset_json: Dictionary = gltf_state.json["asset"]
+	if asset_json.has("extensions"):
+		var asset_extensions: Dictionary = asset_json["extensions"]
+		if asset_extensions.has("KHR_xmp_json_ld"):
+			var asset_xmp: Dictionary = asset_extensions["KHR_xmp_json_ld"]
+			if asset_xmp.has("packet"):
+				var packet: int = int(asset_xmp["packet"])
+				var xmp_array: Array = gltf_state.get_additional_data("KHR_xmp_json_ld")
+				root.set_meta("KHR_xmp_json_ld", xmp_array[packet])
+	return OK
+
+
+# Export process.
+func _export_preflight(gltf_state: GLTFState, root: Node) -> Error:
+	var dcmi_dict: Dictionary = dcmi_license_metadata.to_dictionary()
+	if dcmi_dict.is_empty():
+		return OK
+	dcmi_dict["dc:format"] = "model/gltf"
+	# Add the DCMI XMP JSON dictionary to the document extensions.
+	var state_packets: Array = _get_or_create_state_packets_in_state(gltf_state)
+	state_packets.append(dcmi_dict)
+	return OK
+
+
+func _export_preserialize(gltf_state: GLTFState) -> Error:
+	var state_packets = _get_state_packets_in_state_if_present(gltf_state)
+	if state_packets == null or state_packets.is_empty():
+		return OK
+	var first_packet: Dictionary = state_packets[0]
+	if first_packet.has("dc:format"):
+		if gltf_state.filename.ends_with(".gltf"):
+			first_packet["dc:format"] = "model/gltf+json"
+		else: # If .glb, it's binary. If empty, it's a buffer, also binary.
+			first_packet["dc:format"] = "model/gltf-binary"
+	return OK
+
+
+func _export_node(gltf_state: GLTFState, gltf_node: GLTFNode, node_json: Dictionary, node: Node) -> Error:
+	if not node.has_meta(&"dcmi_license_metadata"):
+		return OK
+	var dcmi_data: DCMILicenseMetadata = node.get_meta(&"dcmi_license_metadata")
+	var dcmi_dict = dcmi_data.to_dictionary()
+	if dcmi_dict.is_empty():
+		return OK
+	# Insert the DCMI dictionary in the state packets and reference it on the node.
+	var state_packets: Array = _get_or_create_state_packets_in_state(gltf_state)
+	var node_extensions: Dictionary
+	# TODO: = node_json.get_or_set_default("extensions", {})
+	if node_json.has("extensions"):
+		node_extensions = node_json["extensions"]
+	else:
+		node_extensions = {}
+		node_json["extensions"] = node_extensions
+	node_extensions["KHR_xmp_json_ld"] = {
+		"packet": state_packets.size()
+	}
+	state_packets.append(dcmi_dict)
+	return OK
+
+
+func _export_post(gltf_state: GLTFState) -> Error:
+	var state_json: Dictionary = gltf_state.json
+	var state_packets = _get_state_packets_in_state_if_present(gltf_state)
+	if state_packets == null or state_packets.is_empty():
+		return OK
+	if not state_packets[0].has("dc:format"):
+		return OK
+	# Reference the DCMI XMP JSON dictionary in the asset.
+	var asset: Dictionary = state_json["asset"]
+	var asset_extensions: Dictionary
+	# TODO: = asset.get_or_set_default("extensions", {})
+	if asset.has("extensions"):
+		asset_extensions = asset["extensions"]
+	else:
+		asset_extensions = {}
+		asset["extensions"] = asset_extensions
+	asset_extensions["KHR_xmp_json_ld"] = {
+		"packet": 0
+	}
+	return OK
+
+
+func _get_state_packets_in_state_if_present(gltf_state: GLTFState): # -> Array?
+	var state_json: Dictionary = gltf_state.json
+	if not state_json.has("extensions"):
+		return null
+	var state_extensions: Dictionary = state_json["extensions"]
+	if not state_extensions.has("KHR_xmp_json_ld"):
+		return null
+	var khr_xmp_ext: Dictionary = state_extensions["KHR_xmp_json_ld"]
+	return khr_xmp_ext["packets"]
+
+
+func _get_or_create_state_packets_in_state(gltf_state: GLTFState) -> Array:
+	var state_json = gltf_state.get_json()
+	var state_extensions: Dictionary
+	if state_json.has("extensions"):
+		state_extensions = state_json["extensions"]
+	else:
+		state_extensions = {}
+		state_json["extensions"] = state_extensions
+	var omi_physics_joint_doc_ext: Dictionary
+	if state_extensions.has("KHR_xmp_json_ld"):
+		omi_physics_joint_doc_ext = state_extensions["KHR_xmp_json_ld"]
+	else:
+		omi_physics_joint_doc_ext = {}
+		state_extensions["KHR_xmp_json_ld"] = omi_physics_joint_doc_ext
+		gltf_state.add_used_extension("KHR_xmp_json_ld", false)
+	var state_packets: Array
+	if omi_physics_joint_doc_ext.has("packets"):
+		state_packets = omi_physics_joint_doc_ext["packets"]
+	else:
+		state_packets = []
+		omi_physics_joint_doc_ext["packets"] = state_packets
+	return state_packets