The forest grows Poly Haven's scanned firs and island trees, their leaves cut out from alpha textures and their trunks blocking through low-poly proxies #16

Merged

agra merged 6 commits from task/3896-the-forest-s-trees-look-like-toys-flat-c into master

2026-10-29 20:06:40 +02:00

agra commented

2026-10-29 18:35:40 +02:00

Owner

Tracker: #3896

The first map's forest of Kenney toy trees becomes 900 of Poly Haven's CC0 scanned trees at their real heights, with bark and leaf textures: 603 firs (fir_tree_01, 12 to 16 m tall) and 297 small coastal broadleaves (island_tree_02, 3 to 4.5 m).

Trees. assets/prefabs/polyhaven_tree.py makes each prefab from the tree's downloaded Poly Haven .blend, reduced to what a forest can draw: the fir from its 54927-triangle LOD2 to 26507 triangles (trunk decimated to a tenth, branches to a half, every needle card kept), the island tree from its 322050-triangle LOD1 to 41009 (trunk and twigs decimated, 12% of its leaf clusters kept, each grown 2.2 times). Each texture is an 8-bit PNG under assets/textures/, the leaf ones RGBA from the diffuse and alpha maps; every .blend and texture has a .md naming its source URL, size, MD5, publication date and CC0 licence. The Kenney tree prefabs are gone; the shipwreck stays Kenney's.
Alpha-cut leaves. A material whose Principled Alpha is fed by the Alpha of the Image Texture feeding its Base Color is a cut-out. hulken draws it in the opaque pass, discarding fragments whose alpha, raised a quarter per mip level so far leaves stay full, is under one half: no sorting. Both faces are lit, each with its own facing normal. The stage stores a texel's colour times its alpha, so that a mip averages only the covered texels' colours, and the cut-out shader divides the alpha out: a cut-out draws its texture's own colour at every distance, as Blender draws a cut-out's straight colour, rather than darkening with each mip level. The stage refuses a non-opaque image to a material that is not a cut-out.
Collision proxies. A mesh whose custom property hulken_collision is true, every ray visibility off so Blender renders nothing of it, collides and draws nothing. Each tree's trunk collides through an 8-sided, 22-triangle frustum; nothing the tree draws collides. The first map's world file shrinks from 17.9 to 12.5 MB.
Cost. tools/forest_bench.sx draws 672 views (a 20 m grid of eyes standing in the forest, 8 yaws each) at 1280x800 offscreen on Metal, keeps each view's fastest of 3 frames, begun to drained, and prints the slowest. On m5, in one session: the Kenney forest of master's first_map.blend 0.62 ms slowest (0.24 ms mean); this branch 4.29 ms slowest (3.20 ms mean), within the 8.3 ms budget. The trees need no distance LODs at this cost, so the bake reads none.
Lighting stays in gamma space, as the rest of the scene lights.
Tests. tests/bake_extract.py gains 13 cases (the cut-out read and its refusals, among them a texture's Color into Alpha, the proxy read, instanced, and its refusals), its water case feeds the water's Alpha from the texture feeding its Base Color, and its linked-prefab case links the fir and its proxy; tests/bake_stage.sx pins the cut-out flag, the premultiplied texel, the refusal and the proxies' triangles in the world alone; tests/cutout_draws.sx draws a checker of opaque and clear texels minified to mip levels 2 and 3 as a cut-out, which must draw the opaque colour as a quad of that colour does; tests/first_map_world.sx pins a fir's trunk keeping a walker clear of its axis and a body falling through its crown to the ground; tests/first_map_views.sx compares a forest view with tests/pixels/forest-metal.png, which fails on master's Kenney forest (138882 of 144000 pixels). Each of 25 mutants of the new rules fails a test.

Agra's check in the app, that the forest looks realistic, is still to come.

Tracker: [#3896](https://sak.swipelab.com/tasks/3896) The first map's forest of Kenney toy trees becomes 900 of Poly Haven's CC0 scanned trees at their real heights, with bark and leaf textures: 603 firs (`fir_tree_01`, 12 to 16 m tall) and 297 small coastal broadleaves (`island_tree_02`, 3 to 4.5 m). - **Trees.** `assets/prefabs/polyhaven_tree.py` makes each prefab from the tree's downloaded Poly Haven `.blend`, reduced to what a forest can draw: the fir from its 54927-triangle `LOD2` to 26507 triangles (trunk decimated to a tenth, branches to a half, every needle card kept), the island tree from its 322050-triangle `LOD1` to 41009 (trunk and twigs decimated, 12% of its leaf clusters kept, each grown 2.2 times). Each texture is an 8-bit PNG under `assets/textures/`, the leaf ones RGBA from the diffuse and alpha maps; every `.blend` and texture has a `.md` naming its source URL, size, MD5, publication date and CC0 licence. The Kenney tree prefabs are gone; the shipwreck stays Kenney's. - **Alpha-cut leaves.** A material whose Principled Alpha is fed by the Alpha of the Image Texture feeding its Base Color is a cut-out. hulken draws it in the opaque pass, discarding fragments whose alpha, raised a quarter per mip level so far leaves stay full, is under one half: no sorting. Both faces are lit, each with its own facing normal. The stage stores a texel's colour times its alpha, so that a mip averages only the covered texels' colours, and the cut-out shader divides the alpha out: a cut-out draws its texture's own colour at every distance, as Blender draws a cut-out's straight colour, rather than darkening with each mip level. The stage refuses a non-opaque image to a material that is not a cut-out. - **Collision proxies.** A mesh whose custom property `hulken_collision` is true, every ray visibility off so Blender renders nothing of it, collides and draws nothing. Each tree's trunk collides through an 8-sided, 22-triangle frustum; nothing the tree draws collides. The first map's world file shrinks from 17.9 to 12.5 MB. - **Cost.** `tools/forest_bench.sx` draws 672 views (a 20 m grid of eyes standing in the forest, 8 yaws each) at 1280x800 offscreen on Metal, keeps each view's fastest of 3 frames, begun to drained, and prints the slowest. On m5, in one session: the Kenney forest of master's `first_map.blend` 0.62 ms slowest (0.24 ms mean); this branch 4.29 ms slowest (3.20 ms mean), within the 8.3 ms budget. The trees need no distance LODs at this cost, so the bake reads none. - **Lighting** stays in gamma space, as the rest of the scene lights. - **Tests.** `tests/bake_extract.py` gains 13 cases (the cut-out read and its refusals, among them a texture's Color into Alpha, the proxy read, instanced, and its refusals), its water case feeds the water's Alpha from the texture feeding its Base Color, and its linked-prefab case links the fir and its proxy; `tests/bake_stage.sx` pins the cut-out flag, the premultiplied texel, the refusal and the proxies' triangles in the world alone; `tests/cutout_draws.sx` draws a checker of opaque and clear texels minified to mip levels 2 and 3 as a cut-out, which must draw the opaque colour as a quad of that colour does; `tests/first_map_world.sx` pins a fir's trunk keeping a walker clear of its axis and a body falling through its crown to the ground; `tests/first_map_views.sx` compares a forest view with `tests/pixels/forest-metal.png`, which fails on master's Kenney forest (138882 of 144000 pixels). Each of 25 mutants of the new rules fails a test. Agra's check in the app, that the forest looks realistic, is still to come.

agra added 1 commit

2026-10-29 18:35:41 +02:00

The bake reads alpha cut-outs and collision proxies, and the renderer draws cut-outs alpha-tested 447b71b4a7

A material whose Principled Alpha is fed by the Alpha of the Image Texture
feeding its Base Color is a cut-out: hulken discards the fragments whose
texel alpha, raised a quarter per mip level, is under one half, and the
stage scales a clear texel's colour by its alpha, as Blender draws it. A
mesh whose custom property hulken_collision is true, every ray visibility
off, is a collision proxy: the stage puts its triangles into the world file
alone.

agra added 3 commits

2026-10-29 18:43:53 +02:00

The forest grows Poly Haven's scanned firs and island trees at their real heights 51c0ff1a96

assets/prefabs/polyhaven_tree.py makes fir_tree_01 and island_tree_02 from
Poly Haven's .blend files: the wood decimated, the island tree's leaf
clusters thinned and grown, the bark and leaf textures as 8-bit PNGs, the
leaves cut out, nothing drawn colliding, and each trunk colliding through a
22-triangle proxy. first_map_prefabs.py replaces the Kenney forest with 900
of them. first_map_world pins a trunk that keeps a walker out and a crown a
falling body passes through, and first_map_views a golden of the forest.

tools/forest_bench.sx times the forest's slowest view at 1280x800 on Metal 6a802c3e0d

The fir's branches decimate to half, keeping their shape 1737d101b5

Decimated to a tenth with the trunk, the branches collapsed into flat
wedges up to 0.96 m² where none of the source's passes 0.01 m²; each wood
material now takes its own share, the branches' largest triangle 0.018 m².

agra added 2 commits

2026-10-29 19:25:46 +02:00

A cut-out draws its texels' own colour at every mip level, dividing out the alpha its texels are stored times d0d70de3e3

The extract's test refuses water's Alpha fed by its Base Color texture, and a texture's Color into Alpha 872d8c439e

agra merged commit 4d035736da into master

2026-10-29 20:06:40 +02:00

agra referenced this pull request from a commit

2026-10-29 20:06:42 +02:00

Merge pull request 'The forest grows Poly Haven's scanned firs and island trees, their leaves cut out from alpha textures and their trunks blocking through low-poly proxies' (#16) from task/3896-the-forest-s-trees-look-like-toys-flat-c into master