Choose Material nocturne, Spectral observatory, Resonant membrane, Liquid optics. Each is supplied in both formats. Each paired comparison loads a complete signed GPU Canvas document on the left and an ordinary, script-free Rive interface on the right. JavaScript owns the right-hand WebGPU renderer, continuous gestures and diagram updates. The bundle can connect the interface to a larger application; GPU Canvas keeps the visual instrument together. This is a hybrid host route, not a native RIVX file player.
Both interfaces retain native Rive buttons and bindings. The hybrid side adds matching GPU control-material skins over ordinary vector labels and geometry, with host pointer handling. Its diagrams use bound native vertices: material / dispersion curves, modal nodal segments and an excitation trace, or three chromatic bending paths. No image readback creates these paths. Liquid optics also permits direct dragging of the lens. The signed side keeps its own native gestures and embedded control-material skins. Both routes use the same fixed finish per instrument: Liquid spring for Nocturne and Membrane, Constructive geometry for Spectral Observatory.
Linked controls propagate changes in either direction. Material, spectral and liquid clocks come from their signed document's view model. The membrane clock follows the official runtime's advance events, starts after the signed document's intro, and applies the same hold/resume rule and pi/2 phase rate as its authored timeline. Unlinking allows independent controls and clocks.
The four paired studies retain the canonical WGSL assets from their respective
private authoring sources. Before native WebGPU compilation, driver.js guards
negative bases of even literal powers with abs: pow(x, 6) becomes
pow(abs(x), 6). This preserves the intended even polynomial while avoiding
WebGPU NaNs for negative bases; the Rive backend already folds those powers.
The comparison therefore shares the scene equations and canonical source, with
an explicit compatibility lowering on the host backend. Other backend precision
and rasterization differences remain measurable.
The script-free .riv files in interfaces/ contain no ScriptAsset,
ScriptedDrawable, ScriptedLayout or shader asset. They need no script signing.
Opening one alone preserves its interface and bindings; the external scene and
host-driven diagrams need this page. Editable RML, Luau, fonts, .rev documents,
source archives and the interface generator stay outside the public site.
The build report and generator are in the private authoring workspace.
Direct entries accept #material-nocturne, #spectral-observatory,
#resonant-membrane and #interactive-optics (or the piece query parameter). An unsupported selection falls back to Spectral Observatory without leaving the comparison.
Legacy interface.riv and runtime/spectral.wgsl paths remain available.
node scripts/check-rivx-gpu-comparison.cjs verifies the available signed studies in Chrome:
linked native controls, host slider/lens gestures, unlinking, responsive layout,
self-hosted playback and actual held-frame pixel agreement. SITE_URL selects
the server; QA_OUTPUT optionally saves screenshots and the measured report.
Additional control checks cover fixed finishes, membrane strike projection and opt-in sound. A single Web Audio bridge prevents doubled sound when the instruments are linked.
The membrane uses a nine-mode impulse bank with position-dependent weights and mode-dependent decay. The signed file owns its visual response and native gestures; both routes use host audio for the audible-frequency sum.
Membrane presentation
Crisp details adds the same mild display-space sharpening kernel to both composed membrane instruments. It is enabled by default and can be switched off; it neither changes modal displacement nor adds samples to the signed shader. The Rive presentation uses up to 2× device pixel density for native text and curves. The signed .riv and its original shader remain unchanged.