fixes, backwards compatibility

src/BulletCollision/NarrowPhaseCollision/btSubSimplexConvexCast.cpp

@@ -72,7 +72,17 @@ bool	btSubsimplexConvexCast::calcTimeOfImpact(
 
 
 	btScalar dist2 = v.length2();
+
+#ifdef BT_USE_DOUBLE_PRECISION
 	btScalar epsilon = SIMD_EPSILON * 10;
+#else
+//todo: epsilon kept for backward compatibility of unit tests.
+//will need to digg deeper to make the algorithm more robust
+//since, a large epsilon can cause an early termination with false
+//positive results (ray intersections that shouldn't be there)
+	btScalar epsilon = btScalar(0.0001);
+#endif //BT_USE_DOUBLE_PRECISION
+
 
 	btVector3	w,p;
 	btScalar VdotR;