use Dispatcher in ConcaveConvexCollisionAlgorithm (so it uses the registered collision algorithm, not hardcoded convexconcave)

improved performance of constraint solver by precalculating the cross product/impulse arm
added collision comparison code: ODE box-box, also sphere-triangle
added safety check into GJK, and an assert for AABB's that are very large
write partid/triangle index outside of GJK

src/BulletCollision/CollisionDispatch/SphereTriangleDetector.cpp

@@ -0,0 +1,201 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "SphereTriangleDetector.h"
+#include "BulletCollision/CollisionShapes/btTriangleShape.h"
+#include "BulletCollision/CollisionShapes/btSphereShape.h"
+
+
+SphereTriangleDetector::SphereTriangleDetector(btSphereShape* sphere,btTriangleShape* triangle)
+:m_sphere(sphere),
+m_triangle(triangle)
+{
+
+}
+
+void	SphereTriangleDetector::getClosestPoints(const ClosestPointInput& input,Result& output,class btIDebugDraw* debugDraw)
+{
+
+	const btTransform& transformA = input.m_transformA;
+	const btTransform& transformB = input.m_transformB;
+
+	btVector3 point,normal;
+	btScalar timeOfImpact = 1.f;
+	btScalar depth = 0.f;
+//	output.m_distance = 1e30f;
+	//move sphere into triangle space
+	btTransform	sphereInTr = transformB.inverseTimes(transformA);
+
+	if (collide(sphereInTr.getOrigin(),point,normal,depth,timeOfImpact))
+	{
+		output.addContactPoint(transformB.getBasis()*normal,transformB*point,depth);
+	}
+
+}
+
+#define MAX_OVERLAP 0.f
+
+
+
+// See also geometrictools.com
+// Basic idea: D = |p - (lo + t0*lv)| where t0 = lv . (p - lo) / lv . lv
+float SegmentSqrDistance(const btVector3& from, const btVector3& to,const btVector3 &p, btVector3 &nearest) {
+	btVector3 diff = p - from;
+	btVector3 v = to - from;
+	float t = v.dot(diff);
+	
+	if (t > 0) {
+		float dotVV = v.dot(v);
+		if (t < dotVV) {
+			t /= dotVV;
+			diff -= t*v;
+		} else {
+			t = 1;
+			diff -= v;
+		}
+	} else
+		t = 0;
+
+	nearest = from + t*v;
+	return diff.dot(diff);	
+}
+
+bool SphereTriangleDetector::facecontains(const btVector3 &p,const btVector3* vertices,btVector3& normal)  {
+	btVector3 lp(p);
+	btVector3 lnormal(normal);
+	
+	return pointInTriangle(vertices, lnormal, &lp);
+}
+
+///combined discrete/continuous sphere-triangle
+bool SphereTriangleDetector::collide(const btVector3& sphereCenter,btVector3 &point, btVector3& resultNormal, btScalar& depth, float &timeOfImpact)
+{
+
+	const btVector3* vertices = &m_triangle->getVertexPtr(0);
+	const btVector3& c = sphereCenter;
+	btScalar r = m_sphere->getRadius();
+
+	btVector3 delta (0,0,0);
+
+	btVector3 normal = (vertices[1]-vertices[0]).cross(vertices[2]-vertices[0]);
+	normal.normalize();
+	btVector3 p1ToCentre = c - vertices[0];
+	float distanceFromPlane = p1ToCentre.dot(normal);
+
+	if (distanceFromPlane < 0.f)
+	{
+		//triangle facing the other way
+	
+		distanceFromPlane *= -1.f;
+		normal *= -1.f;
+	}
+
+	///todo: move this gContactBreakingTreshold into a proper structure
+	extern float gContactBreakingTreshold;
+
+	float contactMargin = gContactBreakingTreshold;
+	bool isInsideContactPlane = distanceFromPlane < r + contactMargin;
+	bool isInsideShellPlane = distanceFromPlane < r;
+	
+	float deltaDotNormal = delta.dot(normal);
+	if (!isInsideShellPlane && deltaDotNormal >= 0.0f)
+		return false;
+
+	// Check for contact / intersection
+	bool hasContact = false;
+	btVector3 contactPoint;
+	if (isInsideContactPlane) {
+		if (facecontains(c,vertices,normal)) {
+			// Inside the contact wedge - touches a point on the shell plane
+			hasContact = true;
+			contactPoint = c - normal*distanceFromPlane;
+		} else {
+			// Could be inside one of the contact capsules
+			float contactCapsuleRadiusSqr = (r + contactMargin) * (r + contactMargin);
+			btVector3 nearestOnEdge;
+			for (int i = 0; i < m_triangle->getNumEdges(); i++) {
+				
+				btPoint3 pa;
+				btPoint3 pb;
+				
+				m_triangle->getEdge(i,pa,pb);
+
+				float distanceSqr = SegmentSqrDistance(pa,pb,c, nearestOnEdge);
+				if (distanceSqr < contactCapsuleRadiusSqr) {
+					// Yep, we're inside a capsule
+					hasContact = true;
+					contactPoint = nearestOnEdge;
+				}
+				
+			}
+		}
+	}
+
+	if (hasContact) {
+		btVector3 contactToCentre = c - contactPoint;
+		float distanceSqr = contactToCentre.length2();
+		if (distanceSqr < (r - MAX_OVERLAP)*(r - MAX_OVERLAP)) {
+			float distance = sqrtf(distanceSqr);
+			if (1)
+			{
+				resultNormal = contactToCentre;
+				resultNormal.normalize();
+			}
+			point = contactPoint;
+			depth = -(r-distance);
+			return true;
+		}
+
+		if (delta.dot(contactToCentre) >= 0.0f) 
+			return false;
+		
+		// Moving towards the contact point -> collision
+		point = contactPoint;
+		timeOfImpact = 0.0f;
+		return true;
+	}
+	
+	return false;
+}
+
+
+bool SphereTriangleDetector::pointInTriangle(const btVector3 vertices[], const btVector3 &normal, btVector3 *p )
+{
+	const btVector3* p1 = &vertices[0];
+	const btVector3* p2 = &vertices[1];
+	const btVector3* p3 = &vertices[2];
+
+	btVector3 edge1( *p2 - *p1 );
+	btVector3 edge2( *p3 - *p2 );
+	btVector3 edge3( *p1 - *p3 );
+
+	btVector3 p1_to_p( *p - *p1 );
+	btVector3 p2_to_p( *p - *p2 );
+	btVector3 p3_to_p( *p - *p3 );
+
+	btVector3 edge1_normal( edge1.cross(normal));
+	btVector3 edge2_normal( edge2.cross(normal));
+	btVector3 edge3_normal( edge3.cross(normal));
+	
+	float r1, r2, r3;
+	r1 = edge1_normal.dot( p1_to_p );
+	r2 = edge2_normal.dot( p2_to_p );
+	r3 = edge3_normal.dot( p3_to_p );
+	if ( ( r1 > 0 && r2 > 0 && r3 > 0 ) ||
+	     ( r1 <= 0 && r2 <= 0 && r3 <= 0 ) )
+		return true;
+	return false;
+
+}