anchor.diff:  
           final double zLen = zmax - zmin;
   
  -        for (int i = 0; i < numPoints * 3; i += 3) {
  +        for (int i = 0, j = 0; i < numPoints * 3; i += 3, j += 4) {
               double z = positions[i + 2];
               double scaledZ = (z - zmin) / zLen;
   
  
positive.code:                 newColors[i + 1] = 0.0;
                  newColors[i + 2] = (c - 0.6666) * 3.0;
              }
          }
  
          return newColors;
  
negative.code: 
          double zLen = zmax - zmin;
  
          for (int i = 0; i < numPoints * 4; i += 4) {
              double z = positions[i + 2];
              double c = (z - zmin) / zLen;
  
  