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951a54cde7
Three changes to what goes into a baked heightfield and how it meets the geometry drawn beside it. The heightfield held every triangle laid in it, including those it does not replace and that are therefore drawn as geometry too - so they were drawn twice, and a roof or a bridge deck left in it bent the ground. Now the first pass lays everything and decides what is replaced; the second lays the replaced triangles together with the neighbours that support them - the owners of the corner samples of the cells around them, without which those cells are not drawn - and only that is written. A first attempt that repeated passes, dropping whatever bordered a hole, eroded the whole terrain away one ring per pass: the edge of the ground is always a hole. The replaced triangles stay replaced in the second pass, since their supports are all there and they have fewer rivals. The triangles bake no longer keep in memory; they wait in a spill file beside the heightfield while the scenery parses. Triangles were refused for an edge longer than 200 m, meant for a water plane under the whole map. On baltyk and tomaszewo that refused thousands of ordinary fields of a hand-modelled terrain, and nothing there comes near a whole-map plane. Only triangles standing on their edge - walls, trees, fences - are refused now. The bake log says why the triangles not replaced are not: standing on edge, too small, under other surfaces, next to a hole. Hand-modelled terrain has triangles hundreds of metres long, elevation-model terrain small ones along the line, and one grid step either loses the detail or samples a field every metre. A bake now writes three heightfields a factor of four apart - <scenario>.ehf, <scenario>.1.ehf, <scenario>.2.ehf - and each triangle goes to the coarsest one that still puts sixteen samples along its longest edge, and to every coarser one too, so the coarsest holds all the ground and a triangle at the edge of a finer field can be replaced by a coarser field beneath it. All of them are picked up together, and a missing or stale one sends the whole set to be baked again. Where fields overlap each other or the geometry, the depth test decides: the terrain is drawn with a polygon offset, negative for the reversed depth buffer and larger for each coarser field, instead of being lowered by 2 cm - so geometry lying on the ground wins at any distance and on any slope, and a finer field wins over a coarser one. On tomaszewo the heightfields went from 176 MB to 10 MB, the load that bakes them from 5:16 to 3:11 and its peak memory from 15.7 GB to 8.5 GB - the scenery alone takes 8.0 - while the triangles replaced went from 37,130 to 40,402. On baltyk from 19 MB to 2 MB, with 6,670 triangles replaced against 4,040.