3D Wood Material

Anchored failures

• A repeated tile is visible at the second board. A canvas tile with repeat prints identical rings on every board and shows its seam in a raking light. Sample object-space position, seed per material, offset geometry through the field.
• Flat roughness looks like plastic. Roughness must move with the grain: pores rougher (+0.19), latewood slightly rougher (+0.13), rays glossier (-0.075). A constant 0.3 gives a uniform bright sheen that never breaks along a ring.
• Colour only, no relief. Rings drawn only in albedo go flat when the light rakes. Feed the same late, pores and fibres into the height and bump it; and clamp the gradient or a hard ring edge turns the normal inside out.
• Grain not following the form. Take along from the member's real axis, not from UV. UV on a chamfered box stretches the pores at the rounded edge and turns a board into a stripe test. With object-space sampling the grain runs straight through corners and end faces switch pores to cells automatically.
• Detail shimmers or crawls at distance and on grazing faces. Every high-frequency layer must fade by its own screen footprint: x *= 1 - smoothstep(a, b, fwidth-of-its-coordinate). Mip the field, and blend late and early toward their averages when fwidth(growth) passes 0.16..0.72. Without this, rings moire into the wall of the board at 3 m.
• Macro looks smeared, blobby, or a faint square lattice shows in the relief. The 1024² field is being magnified past about 2,500 to 4,000 px per unit at grain 1.0: bilinear texel edges leak into the bump derivatives as a grid, pore cells go soft and ring edges dot at the boundary. Raise uGrainScale for a finer fibre size, or raise the bake to 2048 for hero surfaces; never rescale the mesh instead.
• Colour-space slip. The field is data: NoColorSpace, not sRGB. Tone-mapping is applied once at the end (the workshop does it in a hand-written final pass; the demo uses ACESFilmicToneMapping).
• The oil finish lit the raw finish. Materials that differ only by the extra snippet share one program cache key (onBeforeCompile.toString()), so the second material silently reuses the first program. Set a distinct customProgramCacheKey per finish; the Urushi wrapper does.
• Environment lights no roughness variation. envMapIntensity is ignored when only scene.environment is set (r163+); use scene.environmentIntensity. The wood needs a bright window card in the PMREM to show its roughness map; a grey dome hides it.
• Cut faces read the same as the top. Multiply cut faces by 1 - endgrain*(0.045+pores*0.10) and raise their roughness +0.14: end grain drinks finish and stays matt, the fastest cue that this is a solid block.
• Sharp boards float. A box with no arris and no contact shadow looks pasted. Rest each part exactly on its support (y = h/2), bake the shadow map once (shadowMap.autoUpdate=false) and check the close-up for a gap.

Budgets

• Bake once, 1024² RGBA8 with mips (about 5.6 MB GPU), shared by every timber.
• Measured on this Apple GPU in headless Chrome, 13 draw calls and about 2,000 triangles (chamfered boxes, bench, wall) with MSAA on: 1.0 to 1.5 ms per frame at 1440 by 900, 3.4 to 4.5 ms at 2880 by 1800, against 0.65 ms and 4.2 ms for a plain tiled MeshStandardMaterial. The procedural shader costs roughly 0.4 ms at 1x on this scene and vanishes into fill cost at 2x. Fill rate (DPR, MSAA) is the lever, not the noise.
• Cap DPR at 2. Bake shadows once when the boards are static. Pause on document.hidden and reset the clock. Clamp dt to 1/30 s.
• Under prefers-reduced-motion skip the slow orbit and snap camera moves; the still is the composed hero view. Controls stay live.

Self-score of this material (0 to 10, anchored)

Anchors: 2 tiled photo with flat roughness. 4 procedural stripes with albedo only. 6 rings plus relief plus varied roughness, holds at arm's length. 8 pores, rays and end grain hold at 5 cm, finish and wear are believable, no shimmer. 10 scanned-species photograph at every distance.

Provenance

Extracted from the Kibori 木彫 workshop page, where one woodMat() timber shader dresses the walls, benches, tool handles, kumiko lattice and lacquered chests; the generators in demo.html are copied from that file unchanged. The wood was tuned for a close inspect camera, so every constant above is the workshop's own.