feat: Use @typegpu/gl as a fallback when @typegpu/three is made to generate GLSL - #2794

Pull request overview

This PR updates @typegpu/three to support Three.js’s WebGL backend path by switching TypeGPU shader generation to GLSL via @typegpu/gl when WebGL is detected.

Changes:

• Add @typegpu/gl as a peer dependency and wire it into the workspace lockfile.
• Detect WebGL backend in the node builder and apply glOptions({ shaderStage: 'none' }) to tgpu.resolve(...) calls.
• Adjust function-start detection to handle GLSL-style function declarations.

Reviewed changes

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Reviewed changes

• Declared @typegpu/gl as a peer dependency and wired glOptions({ shaderStage: 'none' }) into the three tgpu.resolve calls when the Three.js builder targets WebGL.
• Added isWebGL() backend detection and findFunctionStart() to handle both WGSL (fn name) and GLSL (type name() function declaration syntax.
• Refactored the dependency-assignment resolution in generate() into a local code variable.
• Updated pnpm-lock.yaml to link the new peer dependency.

ℹ️ Docs will need updating once WebGL works

The @typegpu/three docs currently include a caution block stating that the WebGL fallback does not work. Once this feature branch makes it work, that block and the install instructions should be updated.

  ^{｜ Fix it ➔ ｜ View workflow run ｜ Using Kimi K2 (free via Pullfrog for OSS) ｜ 𝕏}

Reviewed changes

Reviewed the delta that removed the WORKAROUND_wgslToGlslFixups post-processor from @typegpu/gl and replaced it with native GLSL generation.

• Removed WORKAROUND_wgslToGlslFixups from packages/typegpu-gl/src/tgpuRootWebGL.ts and its export in packages/typegpu-gl/src/index.ts.
• Added native array support in packages/typegpu-gl/src/glslGenerator.ts: resolveArraySizeSuffix, array-aware declareGlobalConst, declareGlobalVar, typeAnnotation, typeInstantiation, and _emitVarDecl now emit GLSL type name[N] declarations and type[N](...) constructors.
• Added a numericLiteral override that emits GLSL literals without WGSL f/h suffixes, keeps u for u32, and chooses decimal or exponential form for floats.
• Updated @typegpu/gl test snapshots; all 35 @typegpu/gl tests pass.

⚠️ WebGL fallback remains broken for GLSL signatures

packages/typegpu-three/src/typegpu-node.ts:193 still applies forceExplicitVoidReturn(fnCode) unconditionally. The helper inserts -> void after the first ), which corrupts GLSL function signatures such as float foo() into float foo()-> void. This prevents the WebGL fallback from working even though @typegpu/gl now emits valid GLSL.

# forceExplicitVoidReturn corrupts GLSL signatures

## Affected sites
- packages/typegpu-three/src/typegpu-node.ts:193 — `forceExplicitVoidReturn(fnCode)` is applied to GLSL code

## Required outcome
- GLSL function code must not be passed through the WGSL-specific `forceExplicitVoidReturn` helper.

## Suggested approach
Skip `forceExplicitVoidReturn` when `webgl` is true, or detect whether the resolved code already has a return type in a language-agnostic way.

  ^{｜ Fix it ➔ ｜ View workflow run ｜ Using Kimi K2 (free via Pullfrog for OSS) ｜ 𝕏}

Reviewed changes

Reviewed the delta from the previous pullfrog review head (6b3dea9) to the current head (75504e6). The @typegpu/three changes are byte-for-byte identical to the previous iteration; the new commits come from the upstream feat/make-triangle-work-with-gl-fallback feature branch.

• Eagerly reserved gl_Position and sample in packages/typegpu-gl/src/glslGenerator.ts on the first functionDefinition call, so the shaderStage: 'none' path used by @typegpu/three cannot accidentally use these GLSL keywords as identifiers.
• Updated @typegpu/gl inline snapshots to match improved numeric-literal and zero-constructor emission (1i → 1, 0i → 0, 1.5f → 1.5, vec3() → vec3(0)).
• The @typegpu/three files are unchanged from the previous iteration.

🚨 WebGL fallback still blocked by forceExplicitVoidReturn

packages/typegpu-three/src/typegpu-node.ts:193 still passes the resolved function code through forceExplicitVoidReturn. That helper assumes WGSL syntax: it looks for -> to detect an explicit return type and otherwise appends -> void after the first ). GLSL function declarations do not contain ->, so a signature such as float foo() is corrupted into float foo()-> void, which is invalid GLSL. This was raised in the previous pullfrog review and has not been addressed in this rebase.

# forceExplicitVoidReturn corrupts GLSL signatures

## Affected sites
- packages/typegpu-three/src/typegpu-node.ts:193 — `forceExplicitVoidReturn(fnCode)` is applied to GLSL code

## Required outcome
- GLSL function code must not be passed through the WGSL-specific `forceExplicitVoidReturn` helper.

## Suggested approach
Skip `forceExplicitVoidReturn` when `webgl` is true, or detect whether the resolved code already has a return type in a language-agnostic way.

  ^{｜ Fix it ➔ ｜ View workflow run ｜ Using Kimi K2 (free via Pullfrog for OSS) ｜ 𝕏}