fix: honor board solder_mask_color in the 3D render (#957)

[DPS0340]

Fixes #957.

Problem

The 3D viewer hard-coded the FR4 green solder mask, so a board built with solderMaskColor="black" still rendered green even though the Circuit JSON carried solder_mask_color correctly. This made the 3D preview misleading for any board that isn't green.

Two independent code paths had the same hard-coding:

• soldermask-drawing.ts — the textured mask layer derived its palette from material only.
• convert-circuit-json-to-3d-svg.ts — literally const solderMaskColor = colors.fr4SolderMaskGreen.

Change

• Added solderMaskColorPresets covering the documented presets (green, red, blue, purple, black, white, yellow). Each preset is a pair of [mask over bare substrate, mask over copper], since solder mask is translucent and copper underneath lifts the coating — that's what keeps traces readable through the mask.
• Added a shared resolveSolderMaskPreset helper so both render paths agree instead of duplicating the lookup.
• Threaded boardData.solder_mask_color through createSoldermaskTextureForLayer → drawSoldermaskLayer, and applied it in the SVG path too.

Backwards compatibility

Boards with no color, an empty string, or not_specified resolve to undefined and keep the existing material-derived default (FR4 green / FR1), so nothing changes for current boards. Unrecognized values fall back rather than throwing.

Verification

• bunx tsc --noEmit — clean
• bun run format:check — clean
• bun test tests/solder-mask-color.test.ts — 6 pass / 0 fail

Note: bun test has 3 pre-existing failures on main (2 faux-board z-offset tests + the Atari outline SVG test). I confirmed they fail identically on the unmodified checkout, so they're untouched by this change.

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Project	Deployment	Actions	Updated (UTC)
3d-viewer	Ready	Preview, Comment	Jul 26, 2026 6:13am

[DPS0340]

@imrishabh18 @rushabhcodes — either of you able to review this? Fixes #957.

The 3D viewer hard-coded the FR4 green solder mask in two independent paths, so a board built with solderMaskColor="black" still rendered green even though the Circuit JSON carried solder_mask_color correctly. This threads the actual color through both paths, falling back to the existing green when unset.

6 files, +139/-3. CI green and mergeable against main.

[rushabhcodes]

can you share the render with different colors

[DPS0340]

Here are the renders — same board, only solder_mask_color changed, all seven documented presets:

Board face colour actually emitted in the SVG for each:

preset	board face	preset	board face
green	rgb(33,69,46)	black	rgb(39,39,39)
red	rgb(118,39,39)	white	rgb(241,241,239)
blue	rgb(39,56,118)	yellow	rgb(196,182,63)
purple	rgb(85,39,108)

On main every one of these renders rgb(33,69,46) — the hard-coded FR4 green — regardless of what solder_mask_color says, which is #957.

Two things worth pointing out from generating these:

• black and white are the cases that matter. They're the ones a reader would assume are "just a dark/light green tint", and they aren't — black comes out neutral (39,39,39, equal on all channels) rather than a dark green. The test asserts exactly that, since a green-dominated "black" would still look plausible in a screenshot.
• The pad/silkscreen elements stay unchanged across all seven, so the change is confined to the mask material and isn't tinting the whole scene.

Generated by setting solder_mask_color on the existing tests/assets/circuit.json fixture and calling convertCircuitJsonTo3dSvg with the same options as the existing top-view test.

[itsbalamurali]

@rushabhcodes any way that this could land?