anchor.diff:  
           PointCloud cloud = tile.cloud;
   
  -        Uint8List rgba = _execute(tile, cloud.bbox.minimum.height, cloud.bbox.maximum.height);
  -
  -        tile.addData_U8x4("rgba", rgba);
  +        _execute(tile, cloud.bbox.minimum.height, cloud.bbox.maximum.height);
  +
           tile.updateBounds();
           tile.updateShape();
       }
  
positive.code:             assert(result.r >= 0 && result.r <= 255);
              assert(result.g >= 0 && result.g <= 255);
              assert(result.b >= 0 && result.b <= 255);
              newColors[i * 4 + 0] = result.r;
              newColors[i * 4 + 1] = result.g;
              newColors[i * 4 + 2] = result.b;
              newColors[i * 4 + 3] = 255;
          }
  
          return newColors;
      }
  
      _Color _interpolate(double z, double startRange, double endRange, _Color startColor, _Color endColor) {
  
negative.code:             assert(blist is Uint8List);
  
              for (int i = 0; i < tile.numPointsInTile; i++) {
                  rgba[i * 4 + 0] = rlist[i];
                  rgba[i * 4 + 1] = glist[i];
                  rgba[i * 4 + 2] = blist[i];
                  rgba[i * 4 + 3] = 255;
              }
              return rgba;
          }
  
          Float64List positionsZ = tile.data["Z"];
  
          final List<_Stop> stops = _Ramps.list[_rampName];
  