Merge pull request #79833 from puchik/multimesh-custom-aabb

Support custom AABBs within MultiMesh resources

doc/classes/CPUParticles3D.xml

@@ -309,6 +309,10 @@
 		<member name="tangential_accel_min" type="float" setter="set_param_min" getter="get_param_min" default="0.0">
 			Minimum tangent acceleration.
 		</member>
+		<member name="visibility_aabb" type="AABB" setter="set_visibility_aabb" getter="get_visibility_aabb" default="AABB(-4, -4, -4, 8, 8, 8)">
+			The [AABB] that determines the node's region which needs to be visible on screen for the particle system to be active.
+			Grow the box if particles suddenly appear/disappear when the node enters/exits the screen. The [AABB] can be grown via code or with the [b]Particles → Generate AABB[/b] editor tool.
+		</member>
 	</members>
 	<signals>
 		<signal name="finished">

doc/classes/MultiMesh.xml

@@ -92,7 +92,11 @@
 		</member>
 		<member name="color_array" type="PackedColorArray" setter="_set_color_array" getter="_get_color_array" deprecated="Use [method set_instance_color] instead.">
 		</member>
+		<member name="custom_aabb" type="AABB" setter="set_custom_aabb" getter="get_custom_aabb" default="AABB(0, 0, 0, 0, 0, 0)">
+			Custom AABB for this MultiMesh resource. Setting this manually prevents costly runtime AABB recalculations.
+		</member>
 		<member name="custom_data_array" type="PackedColorArray" setter="_set_custom_data_array" getter="_get_custom_data_array" deprecated="Use [method set_instance_custom_data] instead.">
+			See [method set_instance_custom_data].
 		</member>
 		<member name="instance_count" type="int" setter="set_instance_count" getter="get_instance_count" default="0">
 			Number of instances that will get drawn. This clears and (re)sizes the buffers. Setting data format or flags afterwards will have no effect.

doc/classes/RenderingServer.xml

@@ -2332,6 +2332,13 @@
 				[b]Note:[/b] If the buffer is in the engine's internal cache, it will have to be fetched from GPU memory and possibly decompressed. This means [method multimesh_get_buffer] is potentially a slow operation and should be avoided whenever possible.
 			</description>
 		</method>
+		<method name="multimesh_get_custom_aabb" qualifiers="const">
+			<return type="AABB" />
+			<param index="0" name="multimesh" type="RID" />
+			<description>
+				Returns the custom AABB defined for this MultiMesh resource.
+			</description>
+		</method>
 		<method name="multimesh_get_instance_count" qualifiers="const">
 			<return type="int" />
 			<param index="0" name="multimesh" type="RID" />
@@ -2442,6 +2449,14 @@
 				[/codeblock]
 			</description>
 		</method>
+		<method name="multimesh_set_custom_aabb">
+			<return type="void" />
+			<param index="0" name="multimesh" type="RID" />
+			<param index="1" name="aabb" type="AABB" />
+			<description>
+				Sets the custom AABB for this MultiMesh resource.
+			</description>
+		</method>
 		<method name="multimesh_set_mesh">
 			<return type="void" />
 			<param index="0" name="multimesh" type="RID" />

drivers/gles3/storage/mesh_storage.cpp

@@ -1607,6 +1607,9 @@ void MeshStorage::_multimesh_mark_all_dirty(MultiMesh *multimesh, bool p_data, b
 
 void MeshStorage::_multimesh_re_create_aabb(MultiMesh *multimesh, const float *p_data, int p_instances) {
 	ERR_FAIL_COND(multimesh->mesh.is_null());
+	if (multimesh->custom_aabb != AABB()) {
+		return;
+	}
 	AABB aabb;
 	AABB mesh_aabb = mesh_get_aabb(multimesh->mesh);
 	for (int i = 0; i < p_instances; i++) {
@@ -1749,9 +1752,25 @@ RID MeshStorage::multimesh_get_mesh(RID p_multimesh) const {
 	return multimesh->mesh;
 }
 
+void MeshStorage::multimesh_set_custom_aabb(RID p_multimesh, const AABB &p_aabb) {
+	MultiMesh *multimesh = multimesh_owner.get_or_null(p_multimesh);
+	ERR_FAIL_NULL(multimesh);
+	multimesh->custom_aabb = p_aabb;
+	multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+}
+
+AABB MeshStorage::multimesh_get_custom_aabb(RID p_multimesh) const {
+	MultiMesh *multimesh = multimesh_owner.get_or_null(p_multimesh);
+	ERR_FAIL_NULL_V(multimesh, AABB());
+	return multimesh->custom_aabb;
+}
+
 AABB MeshStorage::multimesh_get_aabb(RID p_multimesh) const {
 	MultiMesh *multimesh = multimesh_owner.get_or_null(p_multimesh);
 	ERR_FAIL_NULL_V(multimesh, AABB());
+	if (multimesh->custom_aabb != AABB()) {
+		return multimesh->custom_aabb;
+	}
 	if (multimesh->aabb_dirty) {
 		const_cast<MeshStorage *>(this)->_update_dirty_multimeshes();
 	}
@@ -1943,8 +1962,10 @@ void MeshStorage::multimesh_set_buffer(RID p_multimesh, const Vector<float> &p_b
 		//if we have a mesh set, we need to re-generate the AABB from the new data
 		const float *data = p_buffer.ptr();
 
-		_multimesh_re_create_aabb(multimesh, data, multimesh->instances);
+		if (multimesh->custom_aabb != AABB()) {
-		multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+			_multimesh_re_create_aabb(multimesh, data, multimesh->instances);
+			multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+		}
 	}
 }
 
@@ -2091,9 +2112,11 @@ void MeshStorage::_update_dirty_multimeshes() {
 			}
 
 			if (multimesh->aabb_dirty && multimesh->mesh.is_valid()) {
-				_multimesh_re_create_aabb(multimesh, data, visible_instances);
 				multimesh->aabb_dirty = false;
-				multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+				if (multimesh->custom_aabb != AABB()) {
+					_multimesh_re_create_aabb(multimesh, data, visible_instances);
+					multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+				}
 			}
 		}
 

drivers/gles3/storage/mesh_storage.h

@@ -189,6 +189,7 @@ struct MultiMesh {
 	bool uses_custom_data = false;
 	int visible_instances = -1;
 	AABB aabb;
+	AABB custom_aabb;
 	bool aabb_dirty = false;
 	bool buffer_set = false;
 	uint32_t stride_cache = 0;
@@ -505,6 +506,8 @@ public:
 	virtual void multimesh_instance_set_custom_data(RID p_multimesh, int p_index, const Color &p_color) override;
 
 	virtual RID multimesh_get_mesh(RID p_multimesh) const override;
+	virtual void multimesh_set_custom_aabb(RID p_multimesh, const AABB &p_aabb) override;
+	virtual AABB multimesh_get_custom_aabb(RID p_multimesh) const override;
 	virtual AABB multimesh_get_aabb(RID p_multimesh) const override;
 
 	virtual Transform3D multimesh_instance_get_transform(RID p_multimesh, int p_index) const override;

editor/plugins/cpu_particles_3d_editor_plugin.cpp

@@ -77,9 +77,62 @@ void CPUParticles3DEditor::_menu_option(int p_option) {
 			ur->commit_action(false);
 
 		} break;
+		case MENU_OPTION_GENERATE_AABB: {
+			// Add one second to the default generation lifetime, since the progress is updated every second.
+			generate_seconds->set_value(MAX(1.0, trunc(node->get_lifetime()) + 1.0));
+
+			if (generate_seconds->get_value() >= 11.0 + CMP_EPSILON) {
+				// Only pop up the time dialog if the particle's lifetime is long enough to warrant shortening it.
+				generate_aabb->popup_centered();
+			} else {
+				// Generate the visibility AABB immediately.
+				_generate_aabb();
+			}
+		} break;
 	}
 }
 
+void CPUParticles3DEditor::_generate_aabb() {
+	double time = generate_seconds->get_value();
+
+	double running = 0.0;
+
+	EditorProgress ep("gen_aabb", TTR("Generating Visibility AABB (Waiting for Particle Simulation)"), int(time));
+
+	bool was_emitting = node->is_emitting();
+	if (!was_emitting) {
+		node->set_emitting(true);
+		OS::get_singleton()->delay_usec(1000);
+	}
+
+	AABB rect;
+
+	while (running < time) {
+		uint64_t ticks = OS::get_singleton()->get_ticks_usec();
+		ep.step("Generating...", int(running), true);
+		OS::get_singleton()->delay_usec(1000);
+
+		AABB capture = node->capture_aabb();
+		if (rect == AABB()) {
+			rect = capture;
+		} else {
+			rect.merge_with(capture);
+		}
+
+		running += (OS::get_singleton()->get_ticks_usec() - ticks) / 1000000.0;
+	}
+
+	if (!was_emitting) {
+		node->set_emitting(false);
+	}
+
+	EditorUndoRedoManager *ur = EditorUndoRedoManager::get_singleton();
+	ur->create_action(TTR("Generate Visibility AABB"));
+	ur->add_do_method(node, "set_visibility_aabb", rect);
+	ur->add_undo_method(node, "set_visibility_aabb", node->get_visibility_aabb());
+	ur->commit_action();
+}
+
 void CPUParticles3DEditor::edit(CPUParticles3D *p_particles) {
 	base_node = p_particles;
 	node = p_particles;
@@ -117,9 +170,24 @@ CPUParticles3DEditor::CPUParticles3DEditor() {
 
 	options->set_text(TTR("CPUParticles3D"));
 	options->get_popup()->add_item(TTR("Restart"), MENU_OPTION_RESTART);
+	options->get_popup()->add_item(TTR("Generate AABB"), MENU_OPTION_GENERATE_AABB);
 	options->get_popup()->add_item(TTR("Create Emission Points From Node"), MENU_OPTION_CREATE_EMISSION_VOLUME_FROM_NODE);
 	options->get_popup()->add_item(TTR("Convert to GPUParticles3D"), MENU_OPTION_CONVERT_TO_GPU_PARTICLES);
 	options->get_popup()->connect("id_pressed", callable_mp(this, &CPUParticles3DEditor::_menu_option));
+
+	generate_aabb = memnew(ConfirmationDialog);
+	generate_aabb->set_title(TTR("Generate Visibility AABB"));
+	VBoxContainer *genvb = memnew(VBoxContainer);
+	generate_aabb->add_child(genvb);
+	generate_seconds = memnew(SpinBox);
+	genvb->add_margin_child(TTR("Generation Time (sec):"), generate_seconds);
+	generate_seconds->set_min(0.1);
+	generate_seconds->set_max(25);
+	generate_seconds->set_value(2);
+
+	add_child(generate_aabb);
+
+	generate_aabb->connect("confirmed", callable_mp(this, &CPUParticles3DEditor::_generate_aabb));
 }
 
 void CPUParticles3DEditorPlugin::edit(Object *p_object) {

editor/plugins/cpu_particles_3d_editor_plugin.h

@@ -38,14 +38,19 @@ class CPUParticles3DEditor : public GPUParticles3DEditorBase {
 	GDCLASS(CPUParticles3DEditor, GPUParticles3DEditorBase);
 
 	enum Menu {
+		MENU_OPTION_GENERATE_AABB,
 		MENU_OPTION_CREATE_EMISSION_VOLUME_FROM_NODE,
 		MENU_OPTION_CLEAR_EMISSION_VOLUME,
 		MENU_OPTION_RESTART,
 		MENU_OPTION_CONVERT_TO_GPU_PARTICLES,
 	};
 
+	ConfirmationDialog *generate_aabb = nullptr;
+	SpinBox *generate_seconds = nullptr;
 	CPUParticles3D *node = nullptr;
 
+	void _generate_aabb();
+
 	void _menu_option(int);
 
 	friend class CPUParticles3DEditorPlugin;

editor/plugins/gizmos/cpu_particles_3d_gizmo_plugin.cpp

@@ -31,11 +31,16 @@
 #include "cpu_particles_3d_gizmo_plugin.h"
 
 #include "editor/editor_node.h"
+#include "editor/editor_settings.h"
 #include "editor/editor_string_names.h"
 #include "editor/plugins/node_3d_editor_plugin.h"
 #include "scene/3d/cpu_particles_3d.h"
 
 CPUParticles3DGizmoPlugin::CPUParticles3DGizmoPlugin() {
+	Color gizmo_color = EDITOR_DEF("editors/3d_gizmos/gizmo_colors/particles", Color(0.8, 0.7, 0.4));
+	create_material("particles_material", gizmo_color);
+	gizmo_color.a = MAX((gizmo_color.a - 0.2) * 0.02, 0.0);
+	create_material("particles_solid_material", gizmo_color);
 	create_icon_material("particles_icon", EditorNode::get_singleton()->get_editor_theme()->get_icon(SNAME("GizmoCPUParticles3D"), EditorStringName(EditorIcons)));
 }
 
@@ -56,6 +61,48 @@ bool CPUParticles3DGizmoPlugin::is_selectable_when_hidden() const {
 }
 
 void CPUParticles3DGizmoPlugin::redraw(EditorNode3DGizmo *p_gizmo) {
+	CPUParticles3D *particles = Object::cast_to<CPUParticles3D>(p_gizmo->get_node_3d());
+
+	p_gizmo->clear();
+
+	Vector<Vector3> lines;
+	AABB aabb = particles->get_visibility_aabb();
+
+	for (int i = 0; i < 12; i++) {
+		Vector3 a, b;
+		aabb.get_edge(i, a, b);
+		lines.push_back(a);
+		lines.push_back(b);
+	}
+
+	Vector<Vector3> handles;
+
+	for (int i = 0; i < 3; i++) {
+		Vector3 ax;
+		ax[i] = aabb.position[i] + aabb.size[i];
+		ax[(i + 1) % 3] = aabb.position[(i + 1) % 3] + aabb.size[(i + 1) % 3] * 0.5;
+		ax[(i + 2) % 3] = aabb.position[(i + 2) % 3] + aabb.size[(i + 2) % 3] * 0.5;
+		handles.push_back(ax);
+	}
+
+	Vector3 center = aabb.get_center();
+	for (int i = 0; i < 3; i++) {
+		Vector3 ax;
+		ax[i] = 1.0;
+		handles.push_back(center + ax);
+		lines.push_back(center);
+		lines.push_back(center + ax);
+	}
+
+	Ref<Material> material = get_material("particles_material", p_gizmo);
+
+	p_gizmo->add_lines(lines, material);
+
+	if (p_gizmo->is_selected()) {
+		Ref<Material> solid_material = get_material("particles_solid_material", p_gizmo);
+		p_gizmo->add_solid_box(solid_material, aabb.get_size(), aabb.get_center());
+	}
+
 	Ref<Material> icon = get_material("particles_icon", p_gizmo);
 	p_gizmo->add_unscaled_billboard(icon, 0.05);
 }

scene/3d/cpu_particles_3d.cpp

@@ -101,6 +101,12 @@ void CPUParticles3D::set_randomness_ratio(real_t p_ratio) {
 	randomness_ratio = p_ratio;
 }
 
+void CPUParticles3D::set_visibility_aabb(const AABB &p_aabb) {
+	RS::get_singleton()->multimesh_set_custom_aabb(multimesh, p_aabb);
+	visibility_aabb = p_aabb;
+	update_gizmos();
+}
+
 void CPUParticles3D::set_lifetime_randomness(double p_random) {
 	lifetime_randomness = p_random;
 }
@@ -141,6 +147,10 @@ real_t CPUParticles3D::get_randomness_ratio() const {
 	return randomness_ratio;
 }
 
+AABB CPUParticles3D::get_visibility_aabb() const {
+	return visibility_aabb;
+}
+
 double CPUParticles3D::get_lifetime_randomness() const {
 	return lifetime_randomness;
 }
@@ -520,6 +530,11 @@ bool CPUParticles3D::get_split_scale() {
 	return split_scale;
 }
 
+AABB CPUParticles3D::capture_aabb() const {
+	RS::get_singleton()->multimesh_set_custom_aabb(multimesh, AABB());
+	return RS::get_singleton()->multimesh_get_aabb(multimesh);
+}
+
 void CPUParticles3D::_validate_property(PropertyInfo &p_property) const {
 	if (p_property.name == "emission_sphere_radius" && (emission_shape != EMISSION_SHAPE_SPHERE && emission_shape != EMISSION_SHAPE_SPHERE_SURFACE)) {
 		p_property.usage = PROPERTY_USAGE_NONE;
@@ -1341,6 +1356,7 @@ void CPUParticles3D::convert_from_particles(Node *p_particles) {
 	set_pre_process_time(gpu_particles->get_pre_process_time());
 	set_explosiveness_ratio(gpu_particles->get_explosiveness_ratio());
 	set_randomness_ratio(gpu_particles->get_randomness_ratio());
+	set_visibility_aabb(gpu_particles->get_visibility_aabb());
 	set_use_local_coordinates(gpu_particles->get_use_local_coordinates());
 	set_fixed_fps(gpu_particles->get_fixed_fps());
 	set_fractional_delta(gpu_particles->get_fractional_delta());
@@ -1420,6 +1436,7 @@ void CPUParticles3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_pre_process_time", "secs"), &CPUParticles3D::set_pre_process_time);
 	ClassDB::bind_method(D_METHOD("set_explosiveness_ratio", "ratio"), &CPUParticles3D::set_explosiveness_ratio);
 	ClassDB::bind_method(D_METHOD("set_randomness_ratio", "ratio"), &CPUParticles3D::set_randomness_ratio);
+	ClassDB::bind_method(D_METHOD("set_visibility_aabb", "aabb"), &CPUParticles3D::set_visibility_aabb);
 	ClassDB::bind_method(D_METHOD("set_lifetime_randomness", "random"), &CPUParticles3D::set_lifetime_randomness);
 	ClassDB::bind_method(D_METHOD("set_use_local_coordinates", "enable"), &CPUParticles3D::set_use_local_coordinates);
 	ClassDB::bind_method(D_METHOD("set_fixed_fps", "fps"), &CPUParticles3D::set_fixed_fps);
@@ -1433,6 +1450,7 @@ void CPUParticles3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_pre_process_time"), &CPUParticles3D::get_pre_process_time);
 	ClassDB::bind_method(D_METHOD("get_explosiveness_ratio"), &CPUParticles3D::get_explosiveness_ratio);
 	ClassDB::bind_method(D_METHOD("get_randomness_ratio"), &CPUParticles3D::get_randomness_ratio);
+	ClassDB::bind_method(D_METHOD("get_visibility_aabb"), &CPUParticles3D::get_visibility_aabb);
 	ClassDB::bind_method(D_METHOD("get_lifetime_randomness"), &CPUParticles3D::get_lifetime_randomness);
 	ClassDB::bind_method(D_METHOD("get_use_local_coordinates"), &CPUParticles3D::get_use_local_coordinates);
 	ClassDB::bind_method(D_METHOD("get_fixed_fps"), &CPUParticles3D::get_fixed_fps);
@@ -1461,6 +1479,7 @@ void CPUParticles3D::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "fixed_fps", PROPERTY_HINT_RANGE, "0,1000,1,suffix:FPS"), "set_fixed_fps", "get_fixed_fps");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "fract_delta"), "set_fractional_delta", "get_fractional_delta");
 	ADD_GROUP("Drawing", "");
+	ADD_PROPERTY(PropertyInfo(Variant::AABB, "visibility_aabb", PROPERTY_HINT_NONE, "suffix:m"), "set_visibility_aabb", "get_visibility_aabb");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "local_coords"), "set_use_local_coordinates", "get_use_local_coordinates");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "draw_order", PROPERTY_HINT_ENUM, "Index,Lifetime,View Depth"), "set_draw_order", "get_draw_order");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "mesh", PROPERTY_HINT_RESOURCE_TYPE, "Mesh"), "set_mesh", "get_mesh");
@@ -1665,6 +1684,7 @@ CPUParticles3D::CPUParticles3D() {
 
 	set_emitting(true);
 	set_amount(8);
+	set_visibility_aabb(AABB(Vector3(-4, -4, -4), Vector3(8, 8, 8)));
 
 	set_param_min(PARAM_INITIAL_LINEAR_VELOCITY, 0);
 	set_param_min(PARAM_ANGULAR_VELOCITY, 0);

scene/3d/cpu_particles_3d.h

@@ -138,6 +138,7 @@ private:
 	real_t randomness_ratio = 0.0;
 	double lifetime_randomness = 0.0;
 	double speed_scale = 1.0;
+	AABB visibility_aabb;
 	bool local_coords = false;
 	int fixed_fps = 0;
 	bool fractional_delta = true;
@@ -210,6 +211,7 @@ public:
 	void set_pre_process_time(double p_time);
 	void set_explosiveness_ratio(real_t p_ratio);
 	void set_randomness_ratio(real_t p_ratio);
+	void set_visibility_aabb(const AABB &p_aabb);
 	void set_lifetime_randomness(double p_random);
 	void set_use_local_coordinates(bool p_enable);
 	void set_speed_scale(double p_scale);
@@ -221,6 +223,7 @@ public:
 	double get_pre_process_time() const;
 	real_t get_explosiveness_ratio() const;
 	real_t get_randomness_ratio() const;
+	AABB get_visibility_aabb() const;
 	double get_lifetime_randomness() const;
 	bool get_use_local_coordinates() const;
 	double get_speed_scale() const;
@@ -308,6 +311,8 @@ public:
 
 	void convert_from_particles(Node *p_particles);
 
+	AABB capture_aabb() const;
+
 	CPUParticles3D();
 	~CPUParticles3D();
 };

scene/resources/multimesh.cpp

@@ -269,6 +269,16 @@ Color MultiMesh::get_instance_custom_data(int p_instance) const {
 	return RenderingServer::get_singleton()->multimesh_instance_get_custom_data(multimesh, p_instance);
 }
 
+void MultiMesh::set_custom_aabb(const AABB &p_custom) {
+	custom_aabb = p_custom;
+	RS::get_singleton()->multimesh_set_custom_aabb(multimesh, custom_aabb);
+	emit_changed();
+}
+
+AABB MultiMesh::get_custom_aabb() const {
+	return custom_aabb;
+}
+
 AABB MultiMesh::get_aabb() const {
 	return RenderingServer::get_singleton()->multimesh_get_aabb(multimesh);
 }
@@ -326,6 +336,8 @@ void MultiMesh::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_instance_color", "instance"), &MultiMesh::get_instance_color);
 	ClassDB::bind_method(D_METHOD("set_instance_custom_data", "instance", "custom_data"), &MultiMesh::set_instance_custom_data);
 	ClassDB::bind_method(D_METHOD("get_instance_custom_data", "instance"), &MultiMesh::get_instance_custom_data);
+	ClassDB::bind_method(D_METHOD("set_custom_aabb", "aabb"), &MultiMesh::set_custom_aabb);
+	ClassDB::bind_method(D_METHOD("get_custom_aabb"), &MultiMesh::get_custom_aabb);
 	ClassDB::bind_method(D_METHOD("get_aabb"), &MultiMesh::get_aabb);
 
 	ClassDB::bind_method(D_METHOD("get_buffer"), &MultiMesh::get_buffer);
@@ -334,6 +346,7 @@ void MultiMesh::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "transform_format", PROPERTY_HINT_ENUM, "2D,3D"), "set_transform_format", "get_transform_format");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "use_colors"), "set_use_colors", "is_using_colors");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "use_custom_data"), "set_use_custom_data", "is_using_custom_data");
+	ADD_PROPERTY(PropertyInfo(Variant::AABB, "custom_aabb", PROPERTY_HINT_NONE, "suffix:m"), "set_custom_aabb", "get_custom_aabb");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "instance_count", PROPERTY_HINT_RANGE, "0,16384,1,or_greater"), "set_instance_count", "get_instance_count");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "visible_instance_count", PROPERTY_HINT_RANGE, "-1,16384,1,or_greater"), "set_visible_instance_count", "get_visible_instance_count");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "mesh", PROPERTY_HINT_RESOURCE_TYPE, "Mesh"), "set_mesh", "get_mesh");

scene/resources/multimesh.h

@@ -48,6 +48,7 @@ private:
 	Ref<Mesh> mesh;
 	RID multimesh;
 	TransformFormat transform_format = TRANSFORM_2D;
+	AABB custom_aabb;
 	bool use_colors = false;
 	bool use_custom_data = false;
 	int instance_count = 0;
@@ -103,6 +104,9 @@ public:
 	void set_instance_custom_data(int p_instance, const Color &p_custom_data);
 	Color get_instance_custom_data(int p_instance) const;
 
+	void set_custom_aabb(const AABB &p_custom);
+	AABB get_custom_aabb() const;
+
 	virtual AABB get_aabb() const;
 
 	virtual RID get_rid() const override;

servers/rendering/dummy/storage/mesh_storage.h

@@ -153,6 +153,9 @@ public:
 	virtual void multimesh_instance_set_color(RID p_multimesh, int p_index, const Color &p_color) override {}
 	virtual void multimesh_instance_set_custom_data(RID p_multimesh, int p_index, const Color &p_color) override {}
 
+	virtual void multimesh_set_custom_aabb(RID p_multimesh, const AABB &p_aabb) override {}
+	virtual AABB multimesh_get_custom_aabb(RID p_multimesh) const override { return AABB(); }
+
 	virtual RID multimesh_get_mesh(RID p_multimesh) const override { return RID(); }
 	virtual AABB multimesh_get_aabb(RID p_multimesh) const override { return AABB(); }
 

servers/rendering/renderer_rd/storage_rd/mesh_storage.cpp

@@ -1660,6 +1660,9 @@ void MeshStorage::_multimesh_mark_all_dirty(MultiMesh *multimesh, bool p_data, b
 
 void MeshStorage::_multimesh_re_create_aabb(MultiMesh *multimesh, const float *p_data, int p_instances) {
 	ERR_FAIL_COND(multimesh->mesh.is_null());
+	if (multimesh->custom_aabb != AABB()) {
+		return;
+	}
 	AABB aabb;
 	AABB mesh_aabb = mesh_get_aabb(multimesh->mesh);
 	for (int i = 0; i < p_instances; i++) {
@@ -1960,8 +1963,10 @@ void MeshStorage::multimesh_set_buffer(RID p_multimesh, const Vector<float> &p_b
 		//if we have a mesh set, we need to re-generate the AABB from the new data
 		const float *data = p_buffer.ptr();
 
-		_multimesh_re_create_aabb(multimesh, data, multimesh->instances);
+		if (multimesh->custom_aabb != AABB()) {
-		multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+			_multimesh_re_create_aabb(multimesh, data, multimesh->instances);
+			multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+		}
 	}
 }
 
@@ -2015,9 +2020,26 @@ int MeshStorage::multimesh_get_visible_instances(RID p_multimesh) const {
 	return multimesh->visible_instances;
 }
 
+void MeshStorage::multimesh_set_custom_aabb(RID p_multimesh, const AABB &p_aabb) {
+	MultiMesh *multimesh = multimesh_owner.get_or_null(p_multimesh);
+	ERR_FAIL_NULL(multimesh);
+	multimesh->custom_aabb = p_aabb;
+	multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+}
+
+AABB MeshStorage::multimesh_get_custom_aabb(RID p_multimesh) const {
+	MultiMesh *multimesh = multimesh_owner.get_or_null(p_multimesh);
+	ERR_FAIL_NULL_V(multimesh, AABB());
+	return multimesh->custom_aabb;
+}
+
 AABB MeshStorage::multimesh_get_aabb(RID p_multimesh) const {
 	MultiMesh *multimesh = multimesh_owner.get_or_null(p_multimesh);
 	ERR_FAIL_NULL_V(multimesh, AABB());
+	if (multimesh->custom_aabb != AABB()) {
+		return multimesh->custom_aabb;
+	}
+
 	if (multimesh->aabb_dirty) {
 		const_cast<MeshStorage *>(this)->_update_dirty_multimeshes();
 	}
@@ -2064,9 +2086,11 @@ void MeshStorage::_update_dirty_multimeshes() {
 
 			if (multimesh->aabb_dirty) {
 				//aabb is dirty..
-				_multimesh_re_create_aabb(multimesh, data, visible_instances);
 				multimesh->aabb_dirty = false;
-				multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+				if (multimesh->custom_aabb != AABB()) {
+					_multimesh_re_create_aabb(multimesh, data, visible_instances);
+					multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
+				}
 			}
 		}
 

servers/rendering/renderer_rd/storage_rd/mesh_storage.h

@@ -220,6 +220,7 @@ private:
 		bool uses_custom_data = false;
 		int visible_instances = -1;
 		AABB aabb;
+		AABB custom_aabb;
 		bool aabb_dirty = false;
 		bool buffer_set = false;
 		bool motion_vectors_enabled = false;
@@ -646,6 +647,9 @@ public:
 	virtual void multimesh_set_visible_instances(RID p_multimesh, int p_visible) override;
 	virtual int multimesh_get_visible_instances(RID p_multimesh) const override;
 
+	virtual void multimesh_set_custom_aabb(RID p_multimesh, const AABB &p_aabb) override;
+	virtual AABB multimesh_get_custom_aabb(RID p_multimesh) const override;
+
 	virtual AABB multimesh_get_aabb(RID p_multimesh) const override;
 
 	void _update_dirty_multimeshes();

servers/rendering/rendering_server_default.h

@@ -335,6 +335,9 @@ public:
 	FUNC3(multimesh_instance_set_color, RID, int, const Color &)
 	FUNC3(multimesh_instance_set_custom_data, RID, int, const Color &)
 
+	FUNC2(multimesh_set_custom_aabb, RID, const AABB &)
+	FUNC1RC(AABB, multimesh_get_custom_aabb, RID)
+
 	FUNC1RC(RID, multimesh_get_mesh, RID)
 	FUNC1RC(AABB, multimesh_get_aabb, RID)
 

servers/rendering/storage/mesh_storage.h

@@ -104,6 +104,9 @@ public:
 	virtual void multimesh_instance_set_color(RID p_multimesh, int p_index, const Color &p_color) = 0;
 	virtual void multimesh_instance_set_custom_data(RID p_multimesh, int p_index, const Color &p_color) = 0;
 
+	virtual void multimesh_set_custom_aabb(RID p_multimesh, const AABB &p_aabb) = 0;
+	virtual AABB multimesh_get_custom_aabb(RID p_multimesh) const = 0;
+
 	virtual RID multimesh_get_mesh(RID p_multimesh) const = 0;
 
 	virtual Transform3D multimesh_instance_get_transform(RID p_multimesh, int p_index) const = 0;

servers/rendering_server.cpp

@@ -2427,6 +2427,8 @@ void RenderingServer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("multimesh_instance_set_custom_data", "multimesh", "index", "custom_data"), &RenderingServer::multimesh_instance_set_custom_data);
 	ClassDB::bind_method(D_METHOD("multimesh_get_mesh", "multimesh"), &RenderingServer::multimesh_get_mesh);
 	ClassDB::bind_method(D_METHOD("multimesh_get_aabb", "multimesh"), &RenderingServer::multimesh_get_aabb);
+	ClassDB::bind_method(D_METHOD("multimesh_set_custom_aabb", "multimesh", "aabb"), &RenderingServer::multimesh_set_custom_aabb);
+	ClassDB::bind_method(D_METHOD("multimesh_get_custom_aabb", "multimesh"), &RenderingServer::multimesh_get_custom_aabb);
 	ClassDB::bind_method(D_METHOD("multimesh_instance_get_transform", "multimesh", "index"), &RenderingServer::multimesh_instance_get_transform);
 	ClassDB::bind_method(D_METHOD("multimesh_instance_get_transform_2d", "multimesh", "index"), &RenderingServer::multimesh_instance_get_transform_2d);
 	ClassDB::bind_method(D_METHOD("multimesh_instance_get_color", "multimesh", "index"), &RenderingServer::multimesh_instance_get_color);

servers/rendering_server.h

@@ -413,6 +413,9 @@ public:
 	virtual RID multimesh_get_mesh(RID p_multimesh) const = 0;
 	virtual AABB multimesh_get_aabb(RID p_multimesh) const = 0;
 
+	virtual void multimesh_set_custom_aabb(RID p_mesh, const AABB &p_aabb) = 0;
+	virtual AABB multimesh_get_custom_aabb(RID p_mesh) const = 0;
+
 	virtual Transform3D multimesh_instance_get_transform(RID p_multimesh, int p_index) const = 0;
 	virtual Transform2D multimesh_instance_get_transform_2d(RID p_multimesh, int p_index) const = 0;
 	virtual Color multimesh_instance_get_color(RID p_multimesh, int p_index) const = 0;