bt -> b3 rename

add docs

opencl/gpu_rigidbody/host/b3GpuConstraint4.h

@@ -0,0 +1,29 @@
+
+#ifndef BT_CONSTRAINT4_h
+#define BT_CONSTRAINT4_h
+#include "BulletCommon/btVector3.h"
+
+ATTRIBUTE_ALIGNED16(struct) b3GpuConstraint4
+{
+	BT_DECLARE_ALIGNED_ALLOCATOR();
+
+	btVector3 m_linear;//normal?
+	btVector3 m_worldPos[4];
+	btVector3 m_center;	//	friction
+	float m_jacCoeffInv[4];
+	float m_b[4];
+	float m_appliedRambdaDt[4];
+	float m_fJacCoeffInv[2];	//	friction
+	float m_fAppliedRambdaDt[2];	//	friction
+
+	unsigned int m_bodyA;
+	unsigned int m_bodyB;
+	int m_batchIdx;
+	unsigned int m_paddings;
+
+	inline	void setFrictionCoeff(float value) { m_linear[3] = value; }
+	inline	float getFrictionCoeff() const { return m_linear[3]; }
+};
+
+#endif //BT_CONSTRAINT4_h
+