Expose btManifoldResult::calculateCombinedRestitution and btManifoldResult::calculateCombinedFriction as static member functions, so it can be reused for speculative contacts

Add speculative contact restitution, but disabled by default, not well tested (btDiscreteDynamicsWorld::setApplySpeculativeContactRestitution)
Add --with-double-precision option to premake build system

build/premake4.lua

@@ -13,6 +13,12 @@ solution "0BulletSolution"
 	  description = "Disable demos and extras"	
 	}
 
+	newoption {
+    trigger     = "with-double-precision",
+    description = "Enable double precision build"
+  }
+
+
 	newoption {
     trigger     = "with-nacl",
     description = "Enable Native Client build"
@@ -59,6 +65,10 @@ solution "0BulletSolution"
 
 	postfix="";
 
+  if _OPTIONS["with-double-precision"] then
+  	defines {"BT_USE_DOUBLE_PRECISION"}
+  end
+  
 	if _ACTION == "xcode4" then
 		if _OPTIONS["ios"] then
 			postfix = "ios";

src/BulletCollision/CollisionDispatch/btManifoldResult.cpp

@@ -40,7 +40,7 @@ inline btScalar	calculateCombinedRollingFriction(const btCollisionObject* body0,
 
 
 ///User can override this material combiner by implementing gContactAddedCallback and setting body0->m_collisionFlags |= btCollisionObject::customMaterialCallback;
-inline btScalar	calculateCombinedFriction(const btCollisionObject* body0,const btCollisionObject* body1)
+btScalar	btManifoldResult::calculateCombinedFriction(const btCollisionObject* body0,const btCollisionObject* body1)
 {
 	btScalar friction = body0->getFriction() * body1->getFriction();
 
@@ -53,7 +53,7 @@ inline btScalar	calculateCombinedFriction(const btCollisionObject* body0,const b
 
 }
 
-inline btScalar	calculateCombinedRestitution(const btCollisionObject* body0,const btCollisionObject* body1)
+btScalar	btManifoldResult::calculateCombinedRestitution(const btCollisionObject* body0,const btCollisionObject* body1)
 {
 	return body0->getRestitution() * body1->getRestitution();
 }

src/BulletCollision/CollisionDispatch/btManifoldResult.h

@@ -142,6 +142,9 @@ public:
 		return m_body1Wrap->getCollisionObject();
 	}
 
+	/// in the future we can let the user override the methods to combine restitution and friction
+	static btScalar	calculateCombinedRestitution(const btCollisionObject* body0,const btCollisionObject* body1);
+	static btScalar	calculateCombinedFriction(const btCollisionObject* body0,const btCollisionObject* body1);
 };
 
 #endif //BT_MANIFOLD_RESULT_H

src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp

@@ -209,6 +209,7 @@ m_constraintSolver(constraintSolver),
 m_gravity(0,-10,0),
 m_localTime(0),
 m_synchronizeAllMotionStates(false),
+m_applySpeculativeContactRestitution(false)
 m_profileTimings(0)
 
 {
@@ -486,7 +487,6 @@ void	btDiscreteDynamicsWorld::internalSingleStepSimulation(btScalar timeStep)
 	///perform collision detection
 	performDiscreteCollisionDetection();
 
-
 	calculateSimulationIslands();
 
 	
@@ -962,6 +962,8 @@ void	btDiscreteDynamicsWorld::createPredictiveContacts(btScalar timeStep)
 						bool isPredictive = true;
 						int index = manifold->addManifoldPoint(newPoint, isPredictive);
 						btManifoldPoint& pt = manifold->getContactPoint(index);
+						pt.m_combinedRestitution = 0;
+						pt.m_combinedFriction = btManifoldResult::calculateCombinedFriction(body,sweepResults.m_hitCollisionObject);
 						pt.m_positionWorldOnA = body->getWorldTransform().getOrigin();
 						pt.m_positionWorldOnB = worldPointB;
 
@@ -1055,11 +1057,12 @@ void	btDiscreteDynamicsWorld::integrateTransforms(btScalar timeStep)
 							printf("sm2=%f\n",sm2);
 						}
 #else
-						//response  between two dynamic objects without friction, assuming 0 penetration depth
-						btScalar appliedImpulse = 0.f;
-						btScalar depth = 0.f;
 						
-						appliedImpulse = resolveSingleCollision(body,(btCollisionObject*)sweepResults.m_hitCollisionObject,sweepResults.m_hitPointWorld,sweepResults.m_hitNormalWorld,getSolverInfo(), depth);
+						//don't apply the collision response right now, it will happen next frame
+						//if you really need to, you can uncomment next 3 lines. Note that is uses zero restitution.
+						//btScalar appliedImpulse = 0.f;
+						//btScalar depth = 0.f;
+						//appliedImpulse = resolveSingleCollision(body,(btCollisionObject*)sweepResults.m_hitCollisionObject,sweepResults.m_hitPointWorld,sweepResults.m_hitNormalWorld,getSolverInfo(), depth);
 						
 
 #endif
@@ -1075,6 +1078,42 @@ void	btDiscreteDynamicsWorld::integrateTransforms(btScalar timeStep)
 		}
 
 	}
+
+	///this should probably be switched on by default, but it is not well tested yet
+	if (m_applySpeculativeContactRestitution)
+	{
+		BT_PROFILE("apply speculative contact restitution");
+		for (int i=0;i<m_predictiveManifolds.size();i++)
+		{
+			btPersistentManifold* manifold = m_predictiveManifolds[i];
+			btRigidBody* body0 = btRigidBody::upcast((btCollisionObject*)manifold->getBody0());
+			btRigidBody* body1 = btRigidBody::upcast((btCollisionObject*)manifold->getBody1());
+			
+			for (int p=0;p<manifold->getNumContacts();p++)
+			{
+				const btManifoldPoint& pt = manifold->getContactPoint(p);
+				btScalar combinedRestitution = btManifoldResult::calculateCombinedRestitution(body0, body1);
+
+				if (combinedRestitution>0 && pt.m_appliedImpulse != 0.f)
+				//if (pt.getDistance()>0 && combinedRestitution>0 && pt.m_appliedImpulse != 0.f)
+				{
+					btVector3 imp = -pt.m_normalWorldOnB * pt.m_appliedImpulse* combinedRestitution;
+				
+					const btVector3& pos1 = pt.getPositionWorldOnA();
+					const btVector3& pos2 = pt.getPositionWorldOnB();
+
+					btVector3 rel_pos0 = pos1 - body0->getWorldTransform().getOrigin(); 
+					btVector3 rel_pos1 = pos2 - body1->getWorldTransform().getOrigin();
+
+					if (body0)
+						body0->applyImpulse(imp,rel_pos0);
+					if (body1)
+						body1->applyImpulse(-imp,rel_pos1);
+				}
+			}
+		}
+	}
+	
 }
 
 

src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.h

@@ -58,6 +58,7 @@ protected:
 	bool	m_ownsIslandManager;
 	bool	m_ownsConstraintSolver;
 	bool	m_synchronizeAllMotionStates;
+	bool	m_applySpeculativeContactRestitution;
 
 	btAlignedObjectArray<btActionInterface*>	m_actions;
 	
@@ -202,6 +203,16 @@ public:
 		return m_synchronizeAllMotionStates;
 	}
 
+	void setApplySpeculativeContactRestitution(bool enable)
+	{
+		m_applySpeculativeContactRestitution = enable;
+	}
+	
+	bool getApplySpeculativeContactRestitution() const
+	{
+		return m_applySpeculativeContactRestitution;
+	}
+
 	///Preliminary serialization test for Bullet 2.76. Loading those files requires a separate parser (see Bullet/Demos/SerializeDemo)
 	virtual	void	serialize(btSerializer* serializer);