[2.1.14] voronoi_cell_id generates repeated cell ids near (0,0)

[Hanodest]

voronoi_cell_id seems to always assign the same exact ids to the cells directly top-left and bottom-right from (0,0). Same for the bottom-left and top-right pair. The other ids seem to be randomized properly.

Test expression:

Code: Select all

  {
    type = "noise-expression",
    name = "cell_id",
    expression = [[
      if (
        abs(x) < 200 & abs(y) < 200, 
        voronoi_cell_id {
          x = x,
          y = y,
          seed0 = map_seed,
          seed1 = 0,
          grid_size = 50,
          distance_type = 1,
          jitter = 0.2
        },
        0
      )
    ]],
  },

Visualisation from noise-tools:

noise_vis.png (14.92 KiB) Viewed 221 times

Raw noise values:

noise_values.png (39.9 KiB) Viewed 221 times

[Genhis]

Thanks for the report. I was going to fix it for 2.1 but eventually decided not to because it would significantly alter Fulgora map generation and cause hard borders for old save files. The hash function which picks random values isn't very good unfortunately, I recommend offsetting or multiplying one dimension to get better results.

Code: Select all

Math::hash(regionPosition.x) ^ Math::hash(std::rotr(uint32_t(regionPosition.y), 16)) ^ voronoi.seed