Add export_preserialize to the GLTF export process

4 files changed, 26 insertions, 2 deletions

diff --git a/modules/gltf/doc_classes/GLTFDocumentExtension.xml b/modules/gltf/doc_classes/GLTFDocumentExtension.xml
index 927ffb6aae..24a86fdb75 100644
--- a/modules/gltf/doc_classes/GLTFDocumentExtension.xml
+++ b/modules/gltf/doc_classes/GLTFDocumentExtension.xml
@@ -17,7 +17,7 @@
 			<param index="1" name="gltf_node" type="GLTFNode" />
 			<param index="2" name="scene_node" type="Node" />
 			<description>
-				Part of the export process. This method is run after [method _export_preflight] and before [method _export_node].
+				Part of the export process. This method is run after [method _export_preflight] and before [method _export_preserialize].
 				Runs when converting the data from a Godot scene node. This method can be used to process the Godot scene node data into a format that can be used by [method _export_node].
 			</description>
 		</method>
@@ -28,7 +28,7 @@
 			<param index="2" name="json" type="Dictionary" />
 			<param index="3" name="node" type="Node" />
 			<description>
-				Part of the export process. This method is run after [method _convert_scene_node] and before [method _export_post].
+				Part of the export process. This method is run after [method _export_preserialize] and before [method _export_post].
 				This method can be used to modify the final JSON of each node.
 			</description>
 		</method>
@@ -49,6 +49,14 @@
 				The return value is used to determine if this [GLTFDocumentExtension] instance should be used for exporting a given GLTF file. If [constant OK], the export will use this [GLTFDocumentExtension] instance. If not overridden, [constant OK] is returned.
 			</description>
 		</method>
+		<method name="_export_preserialize" qualifiers="virtual">
+			<return type="int" enum="Error" />
+			<param index="0" name="state" type="GLTFState" />
+			<description>
+				Part of the export process. This method is run after [method _convert_scene_node] and before [method _export_node].
+				This method can be used to alter the state before performing serialization. It runs every time when generating a buffer with [method GLTFDocument.generate_buffer] or writing to the file system with [method GLTFDocument.write_to_filesystem].
+			</description>
+		</method>
 		<method name="_generate_scene_node" qualifiers="virtual">
 			<return type="Node3D" />
 			<param index="0" name="state" type="GLTFState" />
diff --git a/modules/gltf/extensions/gltf_document_extension.cpp b/modules/gltf/extensions/gltf_document_extension.cpp
index 2804a8b0a2..bd9404774a 100644
--- a/modules/gltf/extensions/gltf_document_extension.cpp
+++ b/modules/gltf/extensions/gltf_document_extension.cpp
@@ -44,6 +44,7 @@ void GLTFDocumentExtension::_bind_methods() {
 	// Export process.
 	GDVIRTUAL_BIND(_export_preflight, "state", "root");
 	GDVIRTUAL_BIND(_convert_scene_node, "state", "gltf_node", "scene_node");
+	GDVIRTUAL_BIND(_export_preserialize, "state");
 	GDVIRTUAL_BIND(_export_node, "state", "gltf_node", "json", "node");
 	GDVIRTUAL_BIND(_export_post, "state");
 }
@@ -134,6 +135,13 @@ void GLTFDocumentExtension::convert_scene_node(Ref<GLTFState> p_state, Ref<GLTFN
 	GDVIRTUAL_CALL(_convert_scene_node, p_state, p_gltf_node, p_scene_node);
 }
 
+Error GLTFDocumentExtension::export_preserialize(Ref<GLTFState> p_state) {
+	ERR_FAIL_NULL_V(p_state, ERR_INVALID_PARAMETER);
+	Error err = OK;
+	GDVIRTUAL_CALL(_export_preserialize, p_state, err);
+	return err;
+}
+
 Error GLTFDocumentExtension::export_node(Ref<GLTFState> p_state, Ref<GLTFNode> p_gltf_node, Dictionary &r_dict, Node *p_node) {
 	ERR_FAIL_NULL_V(p_state, ERR_INVALID_PARAMETER);
 	ERR_FAIL_NULL_V(p_gltf_node, ERR_INVALID_PARAMETER);
diff --git a/modules/gltf/extensions/gltf_document_extension.h b/modules/gltf/extensions/gltf_document_extension.h
index d922588a29..c061a3c836 100644
--- a/modules/gltf/extensions/gltf_document_extension.h
+++ b/modules/gltf/extensions/gltf_document_extension.h
@@ -53,6 +53,7 @@ public:
 	// Export process.
 	virtual Error export_preflight(Ref<GLTFState> p_state, Node *p_root);
 	virtual void convert_scene_node(Ref<GLTFState> p_state, Ref<GLTFNode> p_gltf_node, Node *p_scene_node);
+	virtual Error export_preserialize(Ref<GLTFState> p_state);
 	virtual Error export_node(Ref<GLTFState> p_state, Ref<GLTFNode> p_gltf_node, Dictionary &r_json, Node *p_node);
 	virtual Error export_post(Ref<GLTFState> p_state);
 
@@ -69,6 +70,7 @@ public:
 	// Export process.
 	GDVIRTUAL2R(Error, _export_preflight, Ref<GLTFState>, Node *);
 	GDVIRTUAL3(_convert_scene_node, Ref<GLTFState>, Ref<GLTFNode>, Node *);
+	GDVIRTUAL1R(Error, _export_preserialize, Ref<GLTFState>);
 	GDVIRTUAL4R(Error, _export_node, Ref<GLTFState>, Ref<GLTFNode>, Dictionary, Node *);
 	GDVIRTUAL1R(Error, _export_post, Ref<GLTFState>);
 };
diff --git a/modules/gltf/gltf_document.cpp b/modules/gltf/gltf_document.cpp
index d828363e03..923bd6dd6a 100644
--- a/modules/gltf/gltf_document.cpp
+++ b/modules/gltf/gltf_document.cpp
@@ -115,6 +115,12 @@ Error GLTFDocument::_serialize(Ref<GLTFState> p_state, const String &p_path) {
 		p_state->buffers.push_back(Vector<uint8_t>());
 	}
 
+	for (Ref<GLTFDocumentExtension> ext : document_extensions) {
+		ERR_CONTINUE(ext.is_null());
+		Error err = ext->export_preserialize(p_state);
+		ERR_CONTINUE(err != OK);
+	}
+
 	/* STEP CONVERT MESH INSTANCES */
 	_convert_mesh_instances(p_state);