BGE Physics

Clamp objects min/max velocity.
Accessed with bullet physics from the advanced button with dynamic and rigid body objects.
- useful for preventing unstable physics in cases where objects move too fast.
- can add linear velocity with the motion actuator to give smooth motion transitions, without moving too fast.
- minimum velocity means objects don't stop moving.
- python scripts can adjust these values speedup or throttle velocity in the existing direction.

Also made copy properties from an object with no properties work (in case you want to clear all props)

4 files changed, 45 insertions, 4 deletions

diff --git a/source/gameengine/Physics/Bullet/CcdPhysicsController.cpp b/source/gameengine/Physics/Bullet/CcdPhysicsController.cpp
index 2283968801f..0b9da8f46d3 100644
--- a/source/gameengine/Physics/Bullet/CcdPhysicsController.cpp
+++ b/source/gameengine/Physics/Bullet/CcdPhysicsController.cpp
@@ -584,7 +584,19 @@ bool		CcdPhysicsController::SynchronizeMotionStates(float time)
 
 	if (body && !body->isStaticObject())
 	{
-
+		
+		if ((m_cci.m_clamp_vel_max>0.0) || (m_cci.m_clamp_vel_min>0.0))
+		{
+			const btVector3& linvel = body->getLinearVelocity();
+			float len= linvel.length();
+			
+			if((m_cci.m_clamp_vel_max>0.0) && (len > m_cci.m_clamp_vel_max))
+					body->setLinearVelocity(linvel * (m_cci.m_clamp_vel_max / len));
+			
+			else if ((m_cci.m_clamp_vel_min>0.0) && btFuzzyZero(len)==0 && (len < m_cci.m_clamp_vel_min))
+				body->setLinearVelocity(linvel * (m_cci.m_clamp_vel_min / len));
+		}
+		
 		const btVector3& worldPos = body->getCenterOfMassPosition();
 		m_MotionState->setWorldPosition(worldPos[0],worldPos[1],worldPos[2]);
 		
diff --git a/source/gameengine/Physics/Bullet/CcdPhysicsController.h b/source/gameengine/Physics/Bullet/CcdPhysicsController.h
index 245cde2baaa..c7638b36728 100644
--- a/source/gameengine/Physics/Bullet/CcdPhysicsController.h
+++ b/source/gameengine/Physics/Bullet/CcdPhysicsController.h
@@ -214,6 +214,8 @@ struct CcdConstructionInfo
 		m_gravity(0,0,0),
 		m_scaling(1.f,1.f,1.f),
 		m_mass(0.f),
+		m_clamp_vel_min(-1.f), 
+		m_clamp_vel_max(-1.f), 
 		m_restitution(0.1f),
 		m_friction(0.5f),
 		m_linearDamping(0.1f),
@@ -239,6 +241,8 @@ struct CcdConstructionInfo
 	btVector3	m_gravity;
 	btVector3	m_scaling;
 	btScalar	m_mass;
+	btScalar	m_clamp_vel_min;  
+	btScalar	m_clamp_vel_max;  
 	btScalar	m_restitution;
 	btScalar	m_friction;
 	btScalar	m_linearDamping;
@@ -479,7 +483,24 @@ class CcdPhysicsController : public PHY_IPhysicsController
 			}
 			m_cci.m_radius = margin;
 		}
-
+		
+		// velocity clamping
+		virtual void SetLinVelocityMin(float val) 
+		{
+			m_cci.m_clamp_vel_min= val;
+		}
+		virtual float GetLinVelocityMin() const 
+		{
+			return m_cci.m_clamp_vel_min;
+		}
+		virtual void SetLinVelocityMax(float val) 
+		{
+			m_cci.m_clamp_vel_max= val;
+		}
+		virtual float GetLinVelocityMax() const 
+		{
+			return m_cci.m_clamp_vel_max;
+		}
 
 		bool	wantsSleeping();
 
diff --git a/source/gameengine/Physics/common/PHY_IPhysicsController.h b/source/gameengine/Physics/common/PHY_IPhysicsController.h
index 6cba6fa88af..770426b48db 100644
--- a/source/gameengine/Physics/common/PHY_IPhysicsController.h
+++ b/source/gameengine/Physics/common/PHY_IPhysicsController.h
@@ -90,6 +90,12 @@ class PHY_IPhysicsController : public PHY_IController
 		virtual float GetMargin() const=0;
 		virtual float GetRadius() const=0;
 		virtual void  SetRadius(float margin) = 0;
+
+		virtual float GetLinVelocityMin() const=0;
+		virtual void  SetLinVelocityMin(float val) = 0;
+		virtual float GetLinVelocityMax() const=0;
+		virtual void  SetLinVelocityMax(float val) = 0;
+		
 		PHY__Vector3	GetWorldPosition(PHY__Vector3& localpos);
 
 };
diff --git a/source/gameengine/Physics/common/PHY_Pro.h b/source/gameengine/Physics/common/PHY_Pro.h
index 32e63ac2f6d..0249fc3118a 100644
--- a/source/gameengine/Physics/common/PHY_Pro.h
+++ b/source/gameengine/Physics/common/PHY_Pro.h
@@ -35,9 +35,11 @@
 struct PHY_ShapeProps {
 	MT_Scalar  m_mass;                  // Total mass
 	MT_Scalar  m_inertia;               // Inertia, should be a tensor some time 
-	MT_Scalar  m_lin_drag;              // Linear drag (air, water) 0 = concrete, 1 = vacuum 
-	MT_Scalar  m_ang_drag;              // Angular drag
+	MT_Scalar  m_lin_drag;              // Linear drag (air, water) 0 = concrete, 1 = vacuum, inverted and called dampening in blenders UI
+	MT_Scalar  m_ang_drag;              // Angular drag, inverted and called dampening in blenders UI
 	MT_Scalar  m_friction_scaling[3];   // Scaling for anisotropic friction. Component in range [0, 1]   
+	MT_Scalar  m_clamp_vel_min;			// Clamp the minimum velocity, this ensures an object moves at a minimum speed unless its stationary
+	MT_Scalar  m_clamp_vel_max;			// Clamp max velocity
 	bool       m_do_anisotropic;        // Should I do anisotropic friction? 
 	bool       m_do_fh;                 // Should the object have a linear Fh spring?
 	bool       m_do_rot_fh;             // Should the object have an angular Fh spring?