Expose gsplat scene render settings in scene settings UI

[mvaligursky]

The engine now applies a set of gsplat parameters from serialized scene render settings via AppBase#applySceneSettings (Scene#applySettings -> GSplatParams#applySettings). The Editor should expose these in the scene settings UI and serialize them as flat render.gsplat* keys.

Settings to expose (key -> GSplatParams property):

• gsplatRadialSorting -> radialSorting (boolean)
• gsplatLodUpdateDistance -> lodUpdateDistance (number)
• gsplatLodUpdateAngle -> lodUpdateAngle (number)
• gsplatLodBehindPenalty -> lodBehindPenalty (number)
• gsplatLodUnderfillLimit -> lodUnderfillLimit (number)
• gsplatSplatBudget -> splatBudget (number)
• gsplatAlphaClip -> alphaClip (number)
• gsplatAlphaClipForward -> alphaClipForward (number)
• gsplatMinPixelSize -> minPixelSize (number)
• gsplatMinContribution -> minContribution (number)
• gsplatFoveationStrength -> foveationStrength (number)
• gsplatFoveationCenter -> foveationCenter (number)
• gsplatAntiAlias -> antiAlias (boolean)
• gsplatUseFog -> useFog (boolean)
• gsplatColorUpdateAngle -> colorUpdateAngle (number)
• gsplatCooldownTicks -> cooldownTicks (number)
• gsplatDataFormat -> dataFormat (string; one of the GSPLATDATA_* constants)
• gsplatEnableIds -> enableIds (boolean)

Dependency: Requires the engine v2.20 release.

Engine PR: playcanvas/engine#8909

[willeastcott]

Isn't whether a splat was trained to be anti-aliased or not a property of the asset?

[mvaligursky]

Not with unified rendering, where multiple splats are rendered together.