feat(webgl): add disableVertexArrayObject setting to toggle VAOs#77
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Adds a RendererMainSettings.disableVertexArrayObject option (default false) that forces the per-draw attribute-binding path even when VAOs are available. It's a diagnostic/benchmarking switch for A/B-ing the VAO optimization on a target device; no effect on the Canvas renderer. Plumbed like forceWebGL2: RendererMain settings -> Stage -> CoreRendererOptions -> WebGlRenderer -> WebGlContextWrapper, where it gates canUseVertexArrayObject (isWebGl2 still reflects the real context). The example harness reads `?novao=true` and feeds the setting, so the debug overlay can show the difference live. Verified on stress-multi-texture (WebGL1): toggling novao flips VAO:on->off, vertexAttribPointer/enableVertexAttribArray jump from 0 to ~4x the draw count each, bindVertexArray drops to 0, and total GL calls per interval rise ~2.5x. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
Adds a
RendererMainSettings.disableVertexArrayObjectoption (defaultfalse) that forces the per-draw attribute-binding path even when VAOs are available. It's a diagnostic / benchmarking switch for A/B-ing the VAO optimization on real hardware — no effect on the Canvas renderer.The example harness reads
?novao=trueand feeds the setting, so the?debug=trueoverlay shows the difference live on a device.Plumbing
Mirrors
forceWebGL2:RendererMainsettings →Stage→CoreRendererOptions→WebGlRenderer→WebGlContextWrapper, where it gatescanUseVertexArrayObject.isWebGl2still reflects the real context — the flag only controls VAO usage, and the create/bind/delete methods stay capability-based (they're never reached when the gate is off).Verified on real hardware behavior
stress-multi-textureon WebGL1, same scene (~303 draws), togglingnovao:VAO:onVAO:offvertexAttribPointerenableVertexAttribArraybindVertexArraydrawElements73,924 / 18,481 ≈ 4confirms 4vertexAttribPointer+ 4enableVertexAttribArrayper draw return when VAOs are off — the 8 attribute calls/draw the VAO collapses into onebindVertexArray.Testing
pnpm build,pnpm lintclean;pnpm test314/314 — addedWebGlContextWrapper.test.ts(mock-GL unit test) covering: VAOs enabled with the OES extension, disabled without it, and forced off by the flag even when supported.?novao=trueoverlay A/B above.Why it's useful
On a draw-call-bound device (e.g. a TV where per-draw GL cost is ~100µs), this lets you measure the VAO FPS delta directly — run a draw-call-heavy scene with and without
novaoand read it off the overlay. On a fill-bound / vsync-capped setup the GL-call count drops ~2.5× but FPS won't move, which the toggle also makes obvious.🤖 Generated with Claude Code