Add compound shape for rigid body simulation

This patch adds a new compound shape entry to the shape selection
dropdown. It also corrects wrong inertia calculation for convex hulls,
that resulted in strange behavior for small objects.

The compound shape take the collision shapes from its object children
and combines them. This makes it possible to create concave shapes from
primitive shapes. Using this instead of the mesh collision shape is
often many times faster.

Reviewed By: Sergey, Sebastian Parborg

Differential Revision: http://developer.blender.org/D5797

3 files changed, 50 insertions, 9 deletions

diff --git a/extern/bullet2/patches/btPolyhedralConvexShape_Inertia_fix.patch b/extern/bullet2/patches/btPolyhedralConvexShape_Inertia_fix.patch
new file mode 100644
index 00000000000..abafb5855dd
--- /dev/null
+++ b/extern/bullet2/patches/btPolyhedralConvexShape_Inertia_fix.patch
@@ -0,0 +1,41 @@
+diff --git a/extern/bullet2/src/BulletCollision/CollisionShapes/btPolyhedralConvexShape.cpp b/extern/bullet2/src/BulletCollision/CollisionShapes/btPolyhedralConvexShape.cpp
+index 9095c592d87..b831e20c2f9 100644
+--- a/extern/bullet2/src/BulletCollision/CollisionShapes/btPolyhedralConvexShape.cpp
++++ b/extern/bullet2/src/BulletCollision/CollisionShapes/btPolyhedralConvexShape.cpp
+@@ -406,17 +406,17 @@ void	btPolyhedralConvexShape::calculateLocalInertia(btScalar mass,btVector3& ine
+ #ifndef __SPU__
+ 	//not yet, return box inertia
+ 
+-	btScalar margin = getMargin();
++	//btScalar margin = getMargin();
+ 
+ 	btTransform ident;
+ 	ident.setIdentity();
+ 	btVector3 aabbMin,aabbMax;
+-	getAabb(ident,aabbMin,aabbMax);
++	getAabb(ident,aabbMin,aabbMax); // This already contains the margin
+ 	btVector3 halfExtents = (aabbMax-aabbMin)*btScalar(0.5);
+ 
+-	btScalar lx=btScalar(2.)*(halfExtents.x()+margin);
+-	btScalar ly=btScalar(2.)*(halfExtents.y()+margin);
+-	btScalar lz=btScalar(2.)*(halfExtents.z()+margin);
++	btScalar lx=btScalar(2.)*(halfExtents.x());
++	btScalar ly=btScalar(2.)*(halfExtents.y());
++	btScalar lz=btScalar(2.)*(halfExtents.z());
+ 	const btScalar x2 = lx*lx;
+ 	const btScalar y2 = ly*ly;
+ 	const btScalar z2 = lz*lz;
+@@ -476,10 +476,10 @@ void	btPolyhedralConvexAabbCachingShape::recalcLocalAabb()
+ 	
+ 	for ( int i = 0; i < 3; ++i )
+ 	{
+-		m_localAabbMax[i] = _supporting[i][i] + m_collisionMargin;
+-		m_localAabbMin[i] = _supporting[i + 3][i] - m_collisionMargin;
++		m_localAabbMax[i] = _supporting[i][i];
++		m_localAabbMin[i] = _supporting[i + 3][i];
+ 	}
+-	
++
+ 	#else
+ 
+ 	for (int i=0;i<3;i++)
diff --git a/extern/bullet2/src/BulletCollision/CollisionShapes/btCompoundShape.cpp b/extern/bullet2/src/BulletCollision/CollisionShapes/btCompoundShape.cpp
index e8c8c336cd2..1e7f36e0a17 100644
--- a/extern/bullet2/src/BulletCollision/CollisionShapes/btCompoundShape.cpp
+++ b/extern/bullet2/src/BulletCollision/CollisionShapes/btCompoundShape.cpp
@@ -180,7 +180,7 @@ void btCompoundShape::getAabb(const btTransform& trans,btVector3& aabbMin,btVect
 	localHalfExtents += btVector3(getMargin(),getMargin(),getMargin());
 		
 
-	btMatrix3x3 abs_b = trans.getBasis().absolute();  
+	btMatrix3x3 abs_b = trans.getBasis().absolute();
 
 	btVector3 center = trans(localCenter);
 
diff --git a/extern/bullet2/src/BulletCollision/CollisionShapes/btPolyhedralConvexShape.cpp b/extern/bullet2/src/BulletCollision/CollisionShapes/btPolyhedralConvexShape.cpp
index 9095c592d87..b831e20c2f9 100644
--- a/extern/bullet2/src/BulletCollision/CollisionShapes/btPolyhedralConvexShape.cpp
+++ b/extern/bullet2/src/BulletCollision/CollisionShapes/btPolyhedralConvexShape.cpp
@@ -406,17 +406,17 @@ void	btPolyhedralConvexShape::calculateLocalInertia(btScalar mass,btVector3& ine
 #ifndef __SPU__
 	//not yet, return box inertia
 
-	btScalar margin = getMargin();
+	//btScalar margin = getMargin();
 
 	btTransform ident;
 	ident.setIdentity();
 	btVector3 aabbMin,aabbMax;
-	getAabb(ident,aabbMin,aabbMax);
+	getAabb(ident,aabbMin,aabbMax); // This already contains the margin
 	btVector3 halfExtents = (aabbMax-aabbMin)*btScalar(0.5);
 
-	btScalar lx=btScalar(2.)*(halfExtents.x()+margin);
-	btScalar ly=btScalar(2.)*(halfExtents.y()+margin);
-	btScalar lz=btScalar(2.)*(halfExtents.z()+margin);
+	btScalar lx=btScalar(2.)*(halfExtents.x());
+	btScalar ly=btScalar(2.)*(halfExtents.y());
+	btScalar lz=btScalar(2.)*(halfExtents.z());
 	const btScalar x2 = lx*lx;
 	const btScalar y2 = ly*ly;
 	const btScalar z2 = lz*lz;
@@ -476,10 +476,10 @@ void	btPolyhedralConvexAabbCachingShape::recalcLocalAabb()
 	
 	for ( int i = 0; i < 3; ++i )
 	{
-		m_localAabbMax[i] = _supporting[i][i] + m_collisionMargin;
-		m_localAabbMin[i] = _supporting[i + 3][i] - m_collisionMargin;
+		m_localAabbMax[i] = _supporting[i][i];
+		m_localAabbMin[i] = _supporting[i + 3][i];
 	}
-	
+
 	#else
 
 	for (int i=0;i<3;i++)