2026-08-27

Gap: River bank turns too sharp

Short stretches of carved river bank turned more than 30 degrees per meter, cutting a notch instead of a curve. A related question about carve grid resolution surfaced meanwhile.

Gap: River bank turns too sharp

The angle limit ran as a clean-up pass after carving, correcting turns the earlier rules got wrong; it moved into the carving step so the bank builds correctly first time. The dial is now a real-world distance in meters, not grid cells, after two incidents where a cell-based dial changed meaning as resolution changed. On a full island rebuild, sharp-turn violations halved against the unfixed baseline.

Gap: Carve grid too coarse for a smooth bank curve

Five sites were tested at four grid sizes: 4 meters, 1 meter, half a meter, and a tenth of a meter. The angle fix removed sharp turns at every size; resolution controlled the shape between them: coarse stair-stepped, fine stayed smooth. A tenth-of-a-meter grid added a new notch-line artifact and raised cost, scaling with the square of resolution. Half a meter was chosen: clean curves at affordable cost.

![A river bank at a coarse, 4-meter grid, showing a stair-stepped profile](assets/bank-4m.webp) *Before: a 4-meter grid follows the coarse grid instead of the terrain's contour.*

![The same river bank at a half-meter grid, showing a smooth profile](assets/bank-05m.webp) *After: a half-meter grid, eight times finer — a smooth curve instead of steps.*

The fine grid applies only where rivers carve, layered over the coarser base grid and stitched at the seam. A full island build processed 14.45 million fine-resolution cells across 6,541 tiles in just over 17 minutes, with no gaps or cracks across 448,558 vertices. Frame rate in an internal preview dropped to 11-12 frames per second, about a third the coarser rate: the top open item before shipping.

Unresolved: terrain wedges above the water surface

A separate check flagged over fourteen thousand cells where water sat slightly above the ground mesh: the finer carve cut away ground the coarser carve had not, while water stayed keyed to the older ground. The cause was a buffer-width dial defined relative to grid cell size rather than a fixed distance. The wedges were judged a liked visual effect and kept; the check still fails those cells, and moving its threshold remains open.

Wedges of terrain rising through the water surface, an unplanned visual effect nicknamed "river islands" Terrain wedges break the water surface along certain banks — flagged by the check, kept anyway as a liked visual quirk.