added ConstraintSolver/btConeTwistConstraint.cpp to allow for ragdolls

improved hinge constraint: adds limits
added btAtan2Fast
quaternion helper functions
All thanks to Starbreeze Studios / Marcus Hennix, Marten Svanfeldt

src/LinearMath/btQuaternion.h

@@ -212,6 +212,7 @@ public:
 
 	SIMD_FORCE_INLINE const btScalar& getW() const { return m_unusedW; }
 
+	
 };
 
 
@@ -283,6 +284,36 @@ slerp(const btQuaternion& q1, const btQuaternion& q2, const btScalar& t)
 	return q1.slerp(q2, t);
 }
 
+SIMD_FORCE_INLINE btVector3 
+quatRotate(btQuaternion& rotation, btVector3& v) 
+{
+	btQuaternion q = rotation * v;
+	q *= rotation.inverse();
+	return btVector3(q.getX(),q.getY(),q.getZ());
+}
+
+SIMD_FORCE_INLINE btQuaternion 
+shortestArcQuat(btVector3& v0,btVector3& v1) // Game Programming Gems 2.10. make sure v0,v1 are normalized
+{
+	btVector3 c = v0.cross(v1);
+	btScalar  d = v0.dot(v1);
+
+	if (d < -1.0 + SIMD_EPSILON)
+		return btQuaternion(0.0f,1.0f,0.0f,0.0f); // just pick any vector
+
+	btScalar  s = btSqrt((1.0f + d) * 2.0f);
+	btScalar rs = 1.0f / s;
+
+	return btQuaternion(c.getX()*rs,c.getY()*rs,c.getZ()*rs,s * 0.5f);
+}
+
+SIMD_FORCE_INLINE btQuaternion 
+shortestArcQuatNormalize(btVector3& v0,btVector3& v1)
+{
+	v0.normalize();
+	v1.normalize();
+	return shortestArcQuat(v0,v1);
+}
 
 #endif
 

src/LinearMath/btScalar.h

@@ -120,7 +120,6 @@ SIMD_FORCE_INLINE btScalar btPow(btScalar x,btScalar y) { return powf(x,y); }
 	
 #endif
 
-
 #define SIMD_2_PI         btScalar(6.283185307179586232)
 #define SIMD_PI           (SIMD_2_PI * btScalar(0.5))
 #define SIMD_HALF_PI      (SIMD_2_PI * btScalar(0.25))
@@ -135,6 +134,22 @@ SIMD_FORCE_INLINE btScalar btPow(btScalar x,btScalar y) { return powf(x,y); }
 #define SIMD_INFINITY     FLT_MAX
 #endif
 
+SIMD_FORCE_INLINE btScalar btAtan2Fast(btScalar y, btScalar x) 
+{
+	btScalar coeff_1 = SIMD_PI / 4.0f;
+	btScalar coeff_2 = 3.0f * coeff_1;
+	btScalar abs_y = btFabs(y);
+	btScalar angle;
+	if (x >= 0.0f) {
+		btScalar r = (x - abs_y) / (x + abs_y);
+		angle = coeff_1 - coeff_1 * r;
+	} else {
+		btScalar r = (x + abs_y) / (abs_y - x);
+		angle = coeff_2 - coeff_1 * r;
+	}
+	return (y < 0.0f) ? -angle : angle;
+}
+
 SIMD_FORCE_INLINE bool      btFuzzyZero(btScalar x) { return btFabs(x) < SIMD_EPSILON; }
 
 SIMD_FORCE_INLINE bool	btEqual(btScalar a, btScalar eps) {