void CalcRayDirection()
{
Vector3 dir = entity.Velocity;
Vector3 P = new Vector3(bb.Min.X, bb.Min.Y, bb.Max.Z);
tracerP1Y1.SetVectors(P, dir);
P.Y = bb.Max.Y;
tracerP1Y1.SetVectors(P, dir);
P = new Vector3(bb.Max.X, bb.Min.Y, bb.Min.Z);
tracerP2Y1.SetVectors(P, dir);
P.Y = bb.Max.Y;
tracerP2Y2.SetVectors(P, dir);
}