Fix neighbours issue in off-axis walk code

DLASystem.cpp

@@ -109,42 +109,47 @@ void DLASystem::addParticleOnAddCircle() {
         cerr << "FAIL " << pos[0] << " " << pos[1] << endl;
 }
 
+const static size_t NEIGHBOURS = 26;
+
 // send back the position of a neighbour of a given grid cell
 // NOTE: there is no check that the neighbour is inside the grid,
 // this has to be done separately...
 void DLASystem::setPosNeighbour(double setpos[], double pos[], int val) {
-    switch (val) {
-        case 0:
-            setpos[0] = pos[0] + 1.0;
-            setpos[1] = pos[1];
-            setpos[2] = pos[2];
-            break;
-        case 1:
-            setpos[0] = pos[0] - 1.0;
-            setpos[1] = pos[1];
-            setpos[2] = pos[2];
-            break;
-        case 2:
-            setpos[0] = pos[0];
-            setpos[1] = pos[1] + 1.0;
-            setpos[2] = pos[2];
-            break;
-        case 3:
-            setpos[0] = pos[0];
-            setpos[1] = pos[1] - 1.0;
-            setpos[2] = pos[2];
-            break;
-        case 4:
-            setpos[0] = pos[0];
-            setpos[1] = pos[1];
-            setpos[2] = pos[2] + 1.0;
-            break;
-        case 5:
-            setpos[0] = pos[0];
-            setpos[1] = pos[1];
-            setpos[2] = pos[2] - 1.0;
-            break;
-    }
+    const static double offsets[NEIGHBOURS][3] = {
+            // These 6 are first to represent the 6 immediate neighbours of the cell when checking sticking
+            {1,  0,  0},
+            {-1, 0,  0},
+            {0,  1,  0},
+            {0,  -1, 0},
+            {0,  0,  1},
+            {0,  0,  -1},
+
+            // The off-axis neighbours
+            {-1, -1, -1},
+            {-1, -1, 0},
+            {-1, -1, 1},
+            {-1, 0,  -1},
+            {-1, 0,  1},
+            {-1, 1,  -1},
+            {-1, 1,  0},
+            {-1, 1,  1},
+            {0,  -1, -1},
+            {0,  -1, 1},
+            {0,  1,  -1},
+            {0,  1,  1},
+            {1,  -1, -1},
+            {1,  -1, 0},
+            {1,  -1, 1},
+            {1,  0,  -1},
+            {1,  0,  1},
+            {1,  1,  -1},
+            {1,  1,  0},
+            {1,  1,  1}
+    };
+
+    setpos[0] = pos[0] + offsets[val][0];
+    setpos[1] = pos[1] + offsets[val][1];
+    setpos[2] = pos[2] + offsets[val][2];
 }
 
 // when we add a particle to the cluster, we should update the cluster radius
@@ -170,7 +175,7 @@ void DLASystem::updateClusterRadius(double pos[]) {
 
 // make a random move of the last particle in the particleList
 void DLASystem::moveLastParticle() {
-    int rr = rgen.randomInt(6);  // pick a random number in the range 0-3, which direction do we hop?
+    int rr = rgen.randomInt(NEIGHBOURS);  // pick a random number in the range 0-3, which direction do we hop?
     double newpos[3];
 
     Particle *lastP = particleList[numParticles - 1];
@@ -227,7 +232,7 @@ DLASystem::DLASystem(const int maxParticles, const string &csvPath, const double
     // allocate memory for the grid, remember to free the memory in destructor
     grid = new int **[gridSize];
     for (int i = 0; i < gridSize; i++) {
-        grid[i] = new int*[gridSize];
+        grid[i] = new int *[gridSize];
 
         for (int j = 0; j < gridSize; ++j) {
             grid[i][j] = new int[gridSize];