SoftBody3D: Add a property for scaling rest lengths of edge constraints

doc/classes/PhysicsServer3D.xml

@@ -1121,6 +1121,13 @@
 				Returns the pressure coefficient of the given soft body.
 			</description>
 		</method>
+		<method name="soft_body_get_shrinking_factor" qualifiers="const">
+			<return type="float" />
+			<param index="0" name="body" type="RID" />
+			<description>
+				Returns the shrinking factor of the given soft body.
+			</description>
+		</method>
 		<method name="soft_body_get_simulation_precision" qualifiers="const">
 			<return type="int" />
 			<param index="0" name="body" type="RID" />
@@ -1258,6 +1265,14 @@
 				Sets whether the given soft body will be pickable when using object picking.
 			</description>
 		</method>
+		<method name="soft_body_set_shrinking_factor">
+			<return type="void" />
+			<param index="0" name="body" type="RID" />
+			<param index="1" name="shrinking_factor" type="float" />
+			<description>
+				Sets the shrinking factor of the given soft body.
+			</description>
+		</method>
 		<method name="soft_body_set_simulation_precision">
 			<return type="void" />
 			<param index="0" name="body" type="RID" />

doc/classes/PhysicsServer3DExtension.xml

@@ -1049,6 +1049,12 @@
 			<description>
 			</description>
 		</method>
+		<method name="_soft_body_get_shrinking_factor" qualifiers="virtual const">
+			<return type="float" />
+			<param index="0" name="body" type="RID" />
+			<description>
+			</description>
+		</method>
 		<method name="_soft_body_get_simulation_precision" qualifiers="virtual const">
 			<return type="int" />
 			<param index="0" name="body" type="RID" />
@@ -1166,6 +1172,13 @@
 			<description>
 			</description>
 		</method>
+		<method name="_soft_body_set_shrinking_factor" qualifiers="virtual">
+			<return type="void" />
+			<param index="0" name="body" type="RID" />
+			<param index="1" name="shrinking_factor" type="float" />
+			<description>
+			</description>
+		</method>
 		<method name="_soft_body_set_simulation_precision" qualifiers="virtual">
 			<return type="void" />
 			<param index="0" name="body" type="RID" />

doc/classes/SoftBody3D.xml

@@ -124,6 +124,10 @@
 		<member name="ray_pickable" type="bool" setter="set_ray_pickable" getter="is_ray_pickable" default="true">
 			If [code]true[/code], the [SoftBody3D] will respond to [RayCast3D]s.
 		</member>
+		<member name="shrinking_factor" type="float" setter="set_shrinking_factor" getter="get_shrinking_factor" default="0.0">
+			Scales the rest lengths of [SoftBody3D]'s edge constraints. Positive values shrink the mesh, while negative values expand it. For example, a value of [code]0.1[/code] shortens the edges of the mesh by 10%, while [code]-0.1[/code] expands the edges by 10%.
+			[b]Note:[/b] [member shrinking_factor] is best used on surface meshes with pinned points.
+		</member>
 		<member name="simulation_precision" type="int" setter="set_simulation_precision" getter="get_simulation_precision" default="5">
 			Increasing this value will improve the resulting simulation, but can affect performance. Use with care.
 		</member>

modules/godot_physics_3d/godot_physics_server_3d.cpp

@@ -1104,6 +1104,20 @@ real_t GodotPhysicsServer3D::soft_body_get_linear_stiffness(RID p_body) const {
 	return soft_body->get_linear_stiffness();
 }
 
+void GodotPhysicsServer3D::soft_body_set_shrinking_factor(RID p_body, real_t p_shrinking_factor) {
+	GodotSoftBody3D *soft_body = soft_body_owner.get_or_null(p_body);
+	ERR_FAIL_NULL(soft_body);
+
+	soft_body->set_shrinking_factor(p_shrinking_factor);
+}
+
+real_t GodotPhysicsServer3D::soft_body_get_shrinking_factor(RID p_body) const {
+	GodotSoftBody3D *soft_body = soft_body_owner.get_or_null(p_body);
+	ERR_FAIL_NULL_V(soft_body, 0.f);
+
+	return soft_body->get_shrinking_factor();
+}
+
 void GodotPhysicsServer3D::soft_body_set_pressure_coefficient(RID p_body, real_t p_pressure_coefficient) {
 	GodotSoftBody3D *soft_body = soft_body_owner.get_or_null(p_body);
 	ERR_FAIL_NULL(soft_body);

modules/godot_physics_3d/godot_physics_server_3d.h

@@ -289,6 +289,9 @@ public:
 	virtual void soft_body_set_linear_stiffness(RID p_body, real_t p_stiffness) override;
 	virtual real_t soft_body_get_linear_stiffness(RID p_body) const override;
 
+	virtual void soft_body_set_shrinking_factor(RID p_body, real_t p_shrinking_factor) override;
+	virtual real_t soft_body_get_shrinking_factor(RID p_body) const override;
+
 	virtual void soft_body_set_pressure_coefficient(RID p_body, real_t p_pressure_coefficient) override;
 	virtual real_t soft_body_get_pressure_coefficient(RID p_body) const override;
 

modules/godot_physics_3d/godot_soft_body_3d.cpp

@@ -272,8 +272,10 @@ void GodotSoftBody3D::update_area() {
 }
 
 void GodotSoftBody3D::reset_link_rest_lengths() {
+	float multiplier = 1.0 - shrinking_factor;
 	for (Link &link : links) {
 		link.rl = (link.n[0]->x - link.n[1]->x).length();
+		link.rl *= multiplier;
 		link.c1 = link.rl * link.rl;
 	}
 }
@@ -837,6 +839,7 @@ void GodotSoftBody3D::append_link(uint32_t p_node1, uint32_t p_node2) {
 	link.n[0] = node1;
 	link.n[1] = node2;
 	link.rl = (node1->x - node2->x).length();
+	link.rl *= 1.0 - shrinking_factor;
 
 	links.push_back(link);
 }
@@ -894,6 +897,10 @@ void GodotSoftBody3D::set_linear_stiffness(real_t p_val) {
 	linear_stiffness = p_val;
 }
 
+void GodotSoftBody3D::set_shrinking_factor(real_t p_val) {
+	shrinking_factor = p_val;
+}
+
 void GodotSoftBody3D::set_pressure_coefficient(real_t p_val) {
 	pressure_coefficient = p_val;
 }

modules/godot_physics_3d/godot_soft_body_3d.h

@@ -95,6 +95,7 @@ class GodotSoftBody3D : public GodotCollisionObject3D {
 
 	int iteration_count = 5;
 	real_t linear_stiffness = 0.5; // [0,1]
+	real_t shrinking_factor = 0.0; // [-1,1]
 	real_t pressure_coefficient = 0.0; // [-inf,+inf]
 	real_t damping_coefficient = 0.01; // [0,1]
 	real_t drag_coefficient = 0.0; // [0,1]
@@ -191,6 +192,9 @@ public:
 	void set_linear_stiffness(real_t p_val);
 	_FORCE_INLINE_ real_t get_linear_stiffness() const { return linear_stiffness; }
 
+	void set_shrinking_factor(real_t p_val);
+	_FORCE_INLINE_ real_t get_shrinking_factor() const { return shrinking_factor; }
+
 	void set_pressure_coefficient(real_t p_val);
 	_FORCE_INLINE_ real_t get_pressure_coefficient() const { return pressure_coefficient; }
 

modules/jolt_physics/jolt_physics_server_3d.cpp

@@ -1126,6 +1126,20 @@ real_t JoltPhysicsServer3D::soft_body_get_linear_stiffness(RID p_body) const {
 	return (real_t)body->get_stiffness_coefficient();
 }
 
+void JoltPhysicsServer3D::soft_body_set_shrinking_factor(RID p_body, real_t p_shrinking_factor) {
+	JoltSoftBody3D *body = soft_body_owner.get_or_null(p_body);
+	ERR_FAIL_NULL(body);
+
+	return body->set_shrinking_factor((float)p_shrinking_factor);
+}
+
+real_t JoltPhysicsServer3D::soft_body_get_shrinking_factor(RID p_body) const {
+	JoltSoftBody3D *body = soft_body_owner.get_or_null(p_body);
+	ERR_FAIL_NULL_V(body, 0.0);
+
+	return (real_t)body->get_shrinking_factor();
+}
+
 void JoltPhysicsServer3D::soft_body_set_pressure_coefficient(RID p_body, real_t p_coefficient) {
 	JoltSoftBody3D *body = soft_body_owner.get_or_null(p_body);
 	ERR_FAIL_NULL(body);

modules/jolt_physics/jolt_physics_server_3d.h

@@ -331,6 +331,9 @@ public:
 	virtual void soft_body_set_linear_stiffness(RID p_body, real_t p_coefficient) override;
 	virtual real_t soft_body_get_linear_stiffness(RID p_body) const override;
 
+	virtual void soft_body_set_shrinking_factor(RID p_body, real_t p_shrinking_factor) override;
+	virtual real_t soft_body_get_shrinking_factor(RID p_body) const override;
+
 	virtual void soft_body_set_pressure_coefficient(RID p_body, real_t p_coefficient) override;
 	virtual real_t soft_body_get_pressure_coefficient(RID p_body) const override;
 

modules/jolt_physics/objects/jolt_soft_body_3d.cpp

@@ -202,6 +202,10 @@ bool JoltSoftBody3D::_ref_shared_data() {
 		vertex_attrib.mCompliance = vertex_attrib.mShearCompliance = inverse_stiffness;
 
 		settings.CreateConstraints(&vertex_attrib, 1, JPH::SoftBodySharedSettings::EBendType::None);
+		float multiplier = 1.0f - shrinking_factor;
+		for (JPH::SoftBodySharedSettings::Edge &e : settings.mEdgeConstraints) {
+			e.mRestLength *= multiplier;
+		}
 		settings.Optimize();
 	} else {
 		iter_shared_data->value.ref_count++;
@@ -454,6 +458,14 @@ void JoltSoftBody3D::set_stiffness_coefficient(float p_coefficient) {
 	stiffness_coefficient = CLAMP(p_coefficient, 0.0f, 1.0f);
 }
 
+float JoltSoftBody3D::get_shrinking_factor() const {
+	return shrinking_factor;
+}
+
+void JoltSoftBody3D::set_shrinking_factor(float p_shrinking_factor) {
+	shrinking_factor = p_shrinking_factor;
+}
+
 void JoltSoftBody3D::set_pressure(float p_pressure) {
 	if (unlikely(pressure == p_pressure)) {
 		return;

modules/jolt_physics/objects/jolt_soft_body_3d.h

@@ -64,6 +64,7 @@ class JoltSoftBody3D final : public JoltObject3D {
 	float pressure = 0.0f;
 	float linear_damping = 0.01f;
 	float stiffness_coefficient = 0.5f;
+	float shrinking_factor = 0.0f;
 
 	int simulation_precision = 5;
 
@@ -138,6 +139,9 @@ public:
 	float get_stiffness_coefficient() const;
 	void set_stiffness_coefficient(float p_coefficient);
 
+	float get_shrinking_factor() const;
+	void set_shrinking_factor(float p_shrinking_factor);
+
 	float get_pressure() const { return pressure; }
 	void set_pressure(float p_pressure);
 

scene/3d/physics/soft_body_3d.cpp

@@ -352,6 +352,9 @@ void SoftBody3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_linear_stiffness", "linear_stiffness"), &SoftBody3D::set_linear_stiffness);
 	ClassDB::bind_method(D_METHOD("get_linear_stiffness"), &SoftBody3D::get_linear_stiffness);
 
+	ClassDB::bind_method(D_METHOD("set_shrinking_factor", "shrinking_factor"), &SoftBody3D::set_shrinking_factor);
+	ClassDB::bind_method(D_METHOD("get_shrinking_factor"), &SoftBody3D::get_shrinking_factor);
+
 	ClassDB::bind_method(D_METHOD("set_pressure_coefficient", "pressure_coefficient"), &SoftBody3D::set_pressure_coefficient);
 	ClassDB::bind_method(D_METHOD("get_pressure_coefficient"), &SoftBody3D::get_pressure_coefficient);
 
@@ -377,6 +380,7 @@ void SoftBody3D::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "simulation_precision", PROPERTY_HINT_RANGE, "1,100,1"), "set_simulation_precision", "get_simulation_precision");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "total_mass", PROPERTY_HINT_RANGE, "0.01,10000,1"), "set_total_mass", "get_total_mass");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "linear_stiffness", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_linear_stiffness", "get_linear_stiffness");
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "shrinking_factor", PROPERTY_HINT_RANGE, "-1,1,0.01,or_less,or_greater"), "set_shrinking_factor", "get_shrinking_factor");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "pressure_coefficient"), "set_pressure_coefficient", "get_pressure_coefficient");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "damping_coefficient", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_damping_coefficient", "get_damping_coefficient");
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "drag_coefficient", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_drag_coefficient", "get_drag_coefficient");
@@ -643,6 +647,14 @@ real_t SoftBody3D::get_linear_stiffness() {
 	return PhysicsServer3D::get_singleton()->soft_body_get_linear_stiffness(physics_rid);
 }
 
+void SoftBody3D::set_shrinking_factor(real_t p_shrinking_factor) {
+	PhysicsServer3D::get_singleton()->soft_body_set_shrinking_factor(physics_rid, p_shrinking_factor);
+}
+
+real_t SoftBody3D::get_shrinking_factor() {
+	return PhysicsServer3D::get_singleton()->soft_body_get_shrinking_factor(physics_rid);
+}
+
 real_t SoftBody3D::get_pressure_coefficient() {
 	return PhysicsServer3D::get_singleton()->soft_body_get_pressure_coefficient(physics_rid);
 }

scene/3d/physics/soft_body_3d.h

@@ -164,6 +164,9 @@ public:
 	void set_linear_stiffness(real_t p_linear_stiffness);
 	real_t get_linear_stiffness();
 
+	void set_shrinking_factor(real_t p_shrinking_factor);
+	real_t get_shrinking_factor();
+
 	void set_pressure_coefficient(real_t p_pressure_coefficient);
 	real_t get_pressure_coefficient();
 

servers/extensions/physics_server_3d_extension.cpp

@@ -338,6 +338,9 @@ void PhysicsServer3DExtension::_bind_methods() {
 	GDVIRTUAL_BIND(_soft_body_set_linear_stiffness, "body", "linear_stiffness");
 	GDVIRTUAL_BIND(_soft_body_get_linear_stiffness, "body");
 
+	GDVIRTUAL_BIND(_soft_body_set_shrinking_factor, "body", "shrinking_factor");
+	GDVIRTUAL_BIND(_soft_body_get_shrinking_factor, "body");
+
 	GDVIRTUAL_BIND(_soft_body_set_pressure_coefficient, "body", "pressure_coefficient");
 	GDVIRTUAL_BIND(_soft_body_get_pressure_coefficient, "body");
 

servers/extensions/physics_server_3d_extension.h

@@ -445,6 +445,9 @@ public:
 	EXBIND2(soft_body_set_linear_stiffness, RID, real_t)
 	EXBIND1RC(real_t, soft_body_get_linear_stiffness, RID)
 
+	EXBIND2(soft_body_set_shrinking_factor, RID, real_t)
+	EXBIND1RC(real_t, soft_body_get_shrinking_factor, RID)
+
 	EXBIND2(soft_body_set_pressure_coefficient, RID, real_t)
 	EXBIND1RC(real_t, soft_body_get_pressure_coefficient, RID)
 

servers/physics_server_3d.cpp

@@ -876,6 +876,9 @@ void PhysicsServer3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("soft_body_set_linear_stiffness", "body", "stiffness"), &PhysicsServer3D::soft_body_set_linear_stiffness);
 	ClassDB::bind_method(D_METHOD("soft_body_get_linear_stiffness", "body"), &PhysicsServer3D::soft_body_get_linear_stiffness);
 
+	ClassDB::bind_method(D_METHOD("soft_body_set_shrinking_factor", "body", "shrinking_factor"), &PhysicsServer3D::soft_body_set_shrinking_factor);
+	ClassDB::bind_method(D_METHOD("soft_body_get_shrinking_factor", "body"), &PhysicsServer3D::soft_body_get_shrinking_factor);
+
 	ClassDB::bind_method(D_METHOD("soft_body_set_pressure_coefficient", "body", "pressure_coefficient"), &PhysicsServer3D::soft_body_set_pressure_coefficient);
 	ClassDB::bind_method(D_METHOD("soft_body_get_pressure_coefficient", "body"), &PhysicsServer3D::soft_body_get_pressure_coefficient);
 

servers/physics_server_3d.h

@@ -607,6 +607,9 @@ public:
 	virtual void soft_body_set_linear_stiffness(RID p_body, real_t p_stiffness) = 0;
 	virtual real_t soft_body_get_linear_stiffness(RID p_body) const = 0;
 
+	virtual void soft_body_set_shrinking_factor(RID p_body, real_t p_shrinking_factor) = 0;
+	virtual real_t soft_body_get_shrinking_factor(RID p_body) const = 0;
+
 	virtual void soft_body_set_pressure_coefficient(RID p_body, real_t p_pressure_coefficient) = 0;
 	virtual real_t soft_body_get_pressure_coefficient(RID p_body) const = 0;
 

servers/physics_server_3d_dummy.h

@@ -341,6 +341,9 @@ public:
 	virtual void soft_body_set_linear_stiffness(RID p_body, real_t p_stiffness) override {}
 	virtual real_t soft_body_get_linear_stiffness(RID p_body) const override { return 0; }
 
+	virtual void soft_body_set_shrinking_factor(RID p_body, real_t p_shrinking_factor) override {}
+	virtual real_t soft_body_get_shrinking_factor(RID p_body) const override { return 0; }
+
 	virtual void soft_body_set_pressure_coefficient(RID p_body, real_t p_pressure_coefficient) override {}
 	virtual real_t soft_body_get_pressure_coefficient(RID p_body) const override { return 0; }
 

servers/physics_server_3d_wrap_mt.h

@@ -304,6 +304,9 @@ public:
 	FUNC2(soft_body_set_linear_stiffness, RID, real_t);
 	FUNC1RC(real_t, soft_body_get_linear_stiffness, RID);
 
+	FUNC2(soft_body_set_shrinking_factor, RID, real_t);
+	FUNC1RC(real_t, soft_body_get_shrinking_factor, RID);
+
 	FUNC2(soft_body_set_pressure_coefficient, RID, real_t);
 	FUNC1RC(real_t, soft_body_get_pressure_coefficient, RID);