Hi there, it has been a while, just curious if my SVN account still works :)

This commit is an attempt to improve collisions between moving Bullet rigid bodies using (concave) triangle mesh bounds.
Instead of using Gimpact, this we create a btCompoundShape with child shape tetrahedra derived from the surface triangles.
For each triangle, we add a fourth vertex using the centroid, shifting inwards using the triangle normal.
If the centroid hits an internal triangle, we stop. The default depth could be exposed as 'advanced' setting in the user interface.
This solution will be a slower than the original/gimpact solution, but a bit more reliable. 
In the future, it is better to add HACD, convex decomposition to Blender, for moving concave meshes.
See http://kmamou.blogspot.com and the Bullet SDK's Demos/ConvexDecompositionDemo.

5 files changed, 159 insertions, 13 deletions

diff --git a/extern/bullet2/src/BulletCollision/Gimpact/btCompoundFromGimpact.h b/extern/bullet2/src/BulletCollision/Gimpact/btCompoundFromGimpact.h
new file mode 100644
index 00000000000..8d4c35515b1
--- /dev/null
+++ b/extern/bullet2/src/BulletCollision/Gimpact/btCompoundFromGimpact.h
@@ -0,0 +1,98 @@
+#ifndef BT_COMPOUND_FROM_GIMPACT
+#define BT_COMPOUND_FROM_GIMPACT
+
+#include "BulletCollision/CollisionShapes/btCompoundShape.h"
+#include "btGImpactShape.h"
+#include "BulletCollision/NarrowPhaseCollision/btRaycastCallback.h"
+
+struct MyCallback : public btTriangleRaycastCallback
+		{
+			int	m_ignorePart;
+			int	m_ignoreTriangleIndex;
+			
+
+			MyCallback(const btVector3& from, const btVector3& to, int ignorePart, int ignoreTriangleIndex)
+			:btTriangleRaycastCallback(from,to),
+			m_ignorePart(ignorePart),
+			m_ignoreTriangleIndex(ignoreTriangleIndex)
+			{
+				
+			}
+			virtual btScalar reportHit(const btVector3& hitNormalLocal, btScalar hitFraction, int partId, int triangleIndex)
+			{
+				if (partId!=m_ignorePart || triangleIndex!=m_ignoreTriangleIndex)
+				{
+					if (hitFraction < m_hitFraction)
+						return hitFraction;
+				}
+
+				return m_hitFraction;
+			}
+		};
+		struct MyInternalTriangleIndexCallback :public btInternalTriangleIndexCallback
+		{
+			const btGImpactMeshShape*		m_gimpactShape;
+			btCompoundShape*			m_colShape;
+			btScalar	m_depth;
+
+			MyInternalTriangleIndexCallback (btCompoundShape* colShape, const btGImpactMeshShape* meshShape, btScalar depth)
+			:m_colShape(colShape),
+			m_gimpactShape(meshShape),
+			m_depth(depth)
+			{
+			}
+			
+			virtual void internalProcessTriangleIndex(btVector3* triangle,int partId,int  triangleIndex)
+			{
+				btVector3 scale = m_gimpactShape->getLocalScaling();
+				btVector3 v0=triangle[0]*scale;
+				btVector3 v1=triangle[1]*scale;
+				btVector3 v2=triangle[2]*scale;
+				
+				btVector3 centroid = (v0+v1+v2)/3;
+				btVector3 normal = (v1-v0).cross(v2-v0);
+				normal.normalize();
+				btVector3 rayFrom = centroid;
+				btVector3 rayTo = centroid-normal*m_depth;
+				
+				MyCallback cb(rayFrom,rayTo,partId,triangleIndex);
+				
+				m_gimpactShape->processAllTrianglesRay(&cb,rayFrom, rayTo);
+				if (cb.m_hitFraction<1)
+				{
+					rayTo.setInterpolate3(cb.m_from,cb.m_to,cb.m_hitFraction);
+					//rayTo = cb.m_from;
+					//rayTo = rayTo.lerp(cb.m_to,cb.m_hitFraction);
+					//gDebugDraw.drawLine(tr(centroid),tr(centroid+normal),btVector3(1,0,0));
+				}
+				
+
+
+				
+				btConvexHullShape* tet = new btConvexHullShape();
+				tet->addPoint(v0);
+				tet->addPoint(v1);
+				tet->addPoint(v2);
+				tet->addPoint(rayTo);
+				btTransform ident;
+				ident.setIdentity();
+				m_colShape->addChildShape(ident,tet);
+			}
+		};
+		
+btCompoundShape*	btCreateCompoundFromGimpactShape(const btGImpactMeshShape* gimpactMesh, btScalar depth)
+{
+	btCompoundShape* colShape = new btCompoundShape();
+		
+		btTransform tr;
+		tr.setIdentity();
+		
+		MyInternalTriangleIndexCallback cb(colShape,gimpactMesh, depth);
+		btVector3 aabbMin,aabbMax;
+		gimpactMesh->getAabb(tr,aabbMin,aabbMax);
+		gimpactMesh->getMeshInterface()->InternalProcessAllTriangles(&cb,aabbMin,aabbMax);
+
+	return colShape;	
+}	
+
+#endif //BT_COMPOUND_FROM_GIMPACT
\ No newline at end of file
diff --git a/extern/bullet2/src/BulletCollision/Gimpact/btGImpactQuantizedBvh.cpp b/extern/bullet2/src/BulletCollision/Gimpact/btGImpactQuantizedBvh.cpp
index cd4dfdb60e9..4528758c370 100644
--- a/extern/bullet2/src/BulletCollision/Gimpact/btGImpactQuantizedBvh.cpp
+++ b/extern/bullet2/src/BulletCollision/Gimpact/btGImpactQuantizedBvh.cpp
@@ -384,7 +384,7 @@ bool btGImpactQuantizedBvh::rayQuery(
 
 
 SIMD_FORCE_INLINE bool _quantized_node_collision(
-	btGImpactQuantizedBvh * boxset0, btGImpactQuantizedBvh * boxset1,
+	const btGImpactQuantizedBvh * boxset0, const btGImpactQuantizedBvh * boxset1,
 	const BT_BOX_BOX_TRANSFORM_CACHE & trans_cache_1to0,
 	int node0 ,int node1, bool complete_primitive_tests)
 {
@@ -402,7 +402,7 @@ SIMD_FORCE_INLINE bool _quantized_node_collision(
 
 //stackless recursive collision routine
 static void _find_quantized_collision_pairs_recursive(
-	btGImpactQuantizedBvh * boxset0, btGImpactQuantizedBvh * boxset1,
+	const btGImpactQuantizedBvh * boxset0, const btGImpactQuantizedBvh * boxset1,
 	btPairSet * collision_pairs,
 	const BT_BOX_BOX_TRANSFORM_CACHE & trans_cache_1to0,
 	int node0, int node1, bool complete_primitive_tests)
@@ -501,8 +501,8 @@ static void _find_quantized_collision_pairs_recursive(
 }
 
 
-void btGImpactQuantizedBvh::find_collision(btGImpactQuantizedBvh * boxset0, const btTransform & trans0,
-		btGImpactQuantizedBvh * boxset1, const btTransform & trans1,
+void btGImpactQuantizedBvh::find_collision(const btGImpactQuantizedBvh * boxset0, const btTransform & trans0,
+		const btGImpactQuantizedBvh * boxset1, const btTransform & trans1,
 		btPairSet & collision_pairs)
 {
 
diff --git a/extern/bullet2/src/BulletCollision/Gimpact/btGImpactQuantizedBvh.h b/extern/bullet2/src/BulletCollision/Gimpact/btGImpactQuantizedBvh.h
index 9c990774739..e6e52fff4c0 100644
--- a/extern/bullet2/src/BulletCollision/Gimpact/btGImpactQuantizedBvh.h
+++ b/extern/bullet2/src/BulletCollision/Gimpact/btGImpactQuantizedBvh.h
@@ -363,8 +363,8 @@ public:
 	static float getAverageTreeCollisionTime();
 #endif //TRI_COLLISION_PROFILING
 
-	static void find_collision(btGImpactQuantizedBvh * boxset1, const btTransform & trans1,
-		btGImpactQuantizedBvh * boxset2, const btTransform & trans2,
+	static void find_collision(const btGImpactQuantizedBvh * boxset1, const btTransform & trans1,
+		const btGImpactQuantizedBvh * boxset2, const btTransform & trans2,
 		btPairSet & collision_pairs);
 };
 
diff --git a/extern/bullet2/src/BulletCollision/Gimpact/btGImpactShape.cpp b/extern/bullet2/src/BulletCollision/Gimpact/btGImpactShape.cpp
index cceace55e4b..ac8efdf3833 100644
--- a/extern/bullet2/src/BulletCollision/Gimpact/btGImpactShape.cpp
+++ b/extern/bullet2/src/BulletCollision/Gimpact/btGImpactShape.cpp
@@ -25,6 +25,7 @@ subject to the following restrictions:
 
 #define CALC_EXACT_INERTIA 1
 
+
 void btGImpactCompoundShape::calculateLocalInertia(btScalar mass,btVector3& inertia) const
 {
 	lockChildShapes();
@@ -144,6 +145,31 @@ void btGImpactMeshShape::rayTest(const btVector3& rayFrom, const btVector3& rayT
 {
 }
 
+void btGImpactMeshShapePart::processAllTrianglesRay(btTriangleCallback* callback,const btVector3& rayFrom, const btVector3& rayTo) const
+{
+	lockChildShapes();
+
+	btAlignedObjectArray<int> collided;
+	btVector3 rayDir(rayTo - rayFrom);
+	rayDir.normalize();
+	m_box_set.rayQuery(rayDir, rayFrom, collided);
+
+	if(collided.size()==0)
+	{
+		unlockChildShapes();
+		return;
+	}
+
+	int part = (int)getPart();
+	btPrimitiveTriangle triangle;
+	int i = collided.size();
+	while(i--)
+	{
+		getPrimitiveTriangle(collided[i],triangle);
+		callback->processTriangle(triangle.m_vertices,part,collided[i]);
+	}
+	unlockChildShapes();
+}
 
 void btGImpactMeshShapePart::processAllTriangles(btTriangleCallback* callback,const btVector3& aabbMin,const btVector3& aabbMax) const
 {
@@ -182,6 +208,15 @@ void btGImpactMeshShape::processAllTriangles(btTriangleCallback* callback,const
 	}
 }
 
+void btGImpactMeshShape::processAllTrianglesRay(btTriangleCallback* callback,const btVector3& rayFrom, const btVector3& rayTo) const
+{
+	int i = m_mesh_parts.size();
+	while(i--)
+	{
+		m_mesh_parts[i]->processAllTrianglesRay(callback, rayFrom, rayTo);
+	}
+}
+
 
 ///fills the dataBuffer and returns the struct name (and 0 on failure)
 const char*	btGImpactMeshShape::serialize(void* dataBuffer, btSerializer* serializer) const
diff --git a/extern/bullet2/src/BulletCollision/Gimpact/btGImpactShape.h b/extern/bullet2/src/BulletCollision/Gimpact/btGImpactShape.h
index 90015bb9ac0..3d1f48d4776 100644
--- a/extern/bullet2/src/BulletCollision/Gimpact/btGImpactShape.h
+++ b/extern/bullet2/src/BulletCollision/Gimpact/btGImpactShape.h
@@ -51,6 +51,7 @@ enum eGIMPACT_SHAPE_TYPE
 };
 
 
+
 //! Helper class for tetrahedrons
 class btTetrahedronShapeEx:public btBU_Simplex1to4
 {
@@ -192,7 +193,7 @@ public:
 	virtual eGIMPACT_SHAPE_TYPE getGImpactShapeType() const = 0 ;
 
 	//! gets boxset
-	SIMD_FORCE_INLINE btGImpactBoxSet * getBoxSet()
+	SIMD_FORCE_INLINE const btGImpactBoxSet * getBoxSet() const
 	{
 		return &m_box_set;
 	}
@@ -288,6 +289,15 @@ public:
         (void) callback; (void) aabbMin; (void) aabbMax;
 	}
 
+	//! Function for retrieve triangles.
+	/*!
+	It gives the triangles in local space
+	*/
+	virtual void processAllTrianglesRay(btTriangleCallback* /*callback*/,const btVector3& /*rayFrom*/, const btVector3& /*rayTo*/) const
+	{
+		
+	}
+
 	//!@}
 
 };
@@ -635,25 +645,25 @@ public:
 			return (int )numverts;
 		}
 
-		SIMD_FORCE_INLINE void get_indices(int face_index,int &i0,int &i1,int &i2) const
+		SIMD_FORCE_INLINE void get_indices(int face_index,unsigned int &i0,unsigned int &i1,unsigned int &i2) const
 		{
 			if(indicestype == PHY_SHORT)
 			{
-				short * s_indices = (short *)(indexbase + face_index*indexstride);
+				unsigned short* s_indices = (unsigned short *)(indexbase + face_index * indexstride);
 				i0 = s_indices[0];
 				i1 = s_indices[1];
 				i2 = s_indices[2];
 			}
 			else
 			{
-				int * i_indices = (int *)(indexbase + face_index*indexstride);
+				unsigned int * i_indices = (unsigned int *)(indexbase + face_index*indexstride);
 				i0 = i_indices[0];
 				i1 = i_indices[1];
 				i2 = i_indices[2];
 			}
 		}
 
-		SIMD_FORCE_INLINE void get_vertex(int vertex_index, btVector3 & vertex) const
+		SIMD_FORCE_INLINE void get_vertex(unsigned int vertex_index, btVector3 & vertex) const
 		{
 			if(type == PHY_DOUBLE)
 			{
@@ -682,7 +692,7 @@ public:
 
 		virtual void get_primitive_triangle(int prim_index,btPrimitiveTriangle & triangle) const
 		{
-			int indices[3];
+			unsigned int indices[3];
 			get_indices(prim_index,indices[0],indices[1],indices[2]);
 			get_vertex(indices[0],triangle.m_vertices[0]);
 			get_vertex(indices[1],triangle.m_vertices[1]);
@@ -692,7 +702,7 @@ public:
 
 		SIMD_FORCE_INLINE void get_bullet_triangle(int prim_index,btTriangleShapeEx & triangle) const
 		{
-			int indices[3];
+			unsigned int indices[3];
 			get_indices(prim_index,indices[0],indices[1],indices[2]);
 			get_vertex(indices[0],triangle.m_vertices1[0]);
 			get_vertex(indices[1],triangle.m_vertices1[1]);
@@ -885,6 +895,7 @@ public:
     }
 
 	virtual void	processAllTriangles(btTriangleCallback* callback,const btVector3& aabbMin,const btVector3& aabbMax) const;
+	virtual void	processAllTrianglesRay(btTriangleCallback* callback,const btVector3& rayFrom,const btVector3& rayTo) const;
 };
 
 
@@ -1141,6 +1152,8 @@ public:
 	*/
 	virtual void	processAllTriangles(btTriangleCallback* callback,const btVector3& aabbMin,const btVector3& aabbMax) const;
 
+	virtual void	processAllTrianglesRay (btTriangleCallback* callback,const btVector3& rayFrom,const btVector3& rayTo) const;
+
 	virtual	int	calculateSerializeBufferSize() const;
 
 	///fills the dataBuffer and returns the struct name (and 0 on failure)