anchor.diff:              }
               assert(result != null);
   
  -            newColors[i + 0] = result.r / 255.0;
  -            newColors[i + 1] = result.g / 255.0;
  -            newColors[i + 2] = result.b / 255.0;
  +            newColors[j + 0] = result.r / 255.0;
  +            newColors[j + 1] = result.g / 255.0;
  +            newColors[j + 2] = result.b / 255.0;
  +            newColors[j + 3] = 1.0;
           }
   
           return newColors;
  
positive.code: 
          final double zLen = zmax - zmin;
  
          for (int i = 0; i < numPoints * 3; i += 3) {
              double z = positions[i + 2];
              double scaledZ = (z - zmin) / zLen;
  
  
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;
  
  