removed possible bug in computeGridGrid kernel

ComputeGridGrid.cuh

@@ -16,33 +16,30 @@ void computeGridGridForce(const RigidBodyGrid* rho, const RigidBodyGrid* u,
 	const int tid = threadIdx.x;
 	const int r_id = blockIdx.x * blockDim.x + threadIdx.x;
 
-	if (r_id >= rho->getSize()) { // skip threads with nothing to do
-		force[tid] = Vector3(0.0f);
-		torque[tid] = Vector3(0.0f);
-		return;
-	}
-
-	// RBTODO: reduce registers used;
-	//   commenting out interpolateForceD still uses ~40 registers
-	//   -- the innocuous-looking fn below is responsible; consumes ~17 registers!
-	Vector3 r_pos= rho->getPosition(r_id); /* i,j,k value of voxel */
+	force[tid] = Vector3(0.0f);
+	torque[tid] = Vector3(0.0f);
+	if (r_id < rho->getSize()) { // skip threads with nothing to do
+		// RBTODO: reduce registers used;
+		//   commenting out interpolateForceD still uses ~40 registers
+		//   -- the innocuous-looking fn below is responsible; consumes ~17 registers!
+		Vector3 r_pos= rho->getPosition(r_id); /* i,j,k value of voxel */
 
-	r_pos = basis_rho.transform( r_pos ) + origin_rho_minus_origin_u; /* real space */
-	const Vector3 u_ijk_float = basis_u_inv.transform( r_pos );
+		r_pos = basis_rho.transform( r_pos ) + origin_rho_minus_origin_u; /* real space */
+		const Vector3 u_ijk_float = basis_u_inv.transform( r_pos );
 
-	// RBTODO What about non-unit delta?
-	/* Vector3 tmpf  = Vector3(0.0f); */
-	/* float tmpe = 0.0f; */
-	/* const ForceEnergy fe = ForceEnergy( tmpf, tmpe); */
-	const ForceEnergy fe = u->interpolateForceDLinearly( u_ijk_float ); /* in coord frame of u */
-	force[tid] = fe.f;
+		// RBTODO What about non-unit delta?
+		/* Vector3 tmpf  = Vector3(0.0f); */
+		/* float tmpe = 0.0f; */
+		/* const ForceEnergy fe = ForceEnergy( tmpf, tmpe); */
+		const ForceEnergy fe = u->interpolateForceDLinearly( u_ijk_float ); /* in coord frame of u */
+		force[tid] = fe.f;
 
-	const float r_val = rho->val[r_id]; /* maybe move to beginning of function?  */
-	force[tid] = basis_u_inv.transpose().transform( r_val*force[tid] ); /* transform to lab frame, with correct scaling factor */
+		const float r_val = rho->val[r_id]; /* maybe move to beginning of function?  */
+		force[tid] = basis_u_inv.transpose().transform( r_val*force[tid] ); /* transform to lab frame, with correct scaling factor */
 
-	// Calculate torque about origin_u in the lab frame
-	torque[tid] = r_pos.cross(force[tid]);				// RBTODO: test if sign is correct!
-	
+		// Calculate torque about origin_u in the lab frame
+		torque[tid] = r_pos.cross(force[tid]);				// RBTODO: test if sign is correct!
+	}
 
 	// Reduce force and torques
 	// http://www.cuvilib.com/Reduction.pdf