The world-unit standard deviation of a splat along the view ray,
sigmaRay = 1/√(rᵀ Σ⁻¹ r) — the sum projection's ray-integral scale. ONE
graph for the visual vertex stage (sum-projection variants) and the pick
factory, which must weigh a splat by the amplitude the draw emits. A plain
graph builder (not a TSL Fn), so it emits exactly the statements inlined
at the call site. GLSL twin: the uProjectionMode == 0 block of
shader-glsl.ts (and of picking/gsplat/shaders.ts).
The world-unit standard deviation of a splat along the view ray,
sigmaRay = 1/√(rᵀ Σ⁻¹ r)— the sum projection's ray-integral scale. ONE graph for the visual vertex stage (sum-projection variants) and the pick factory, which must weigh a splat by the amplitude the draw emits. A plain graph builder (not a TSLFn), so it emits exactly the statements inlined at the call site. GLSL twin: theuProjectionMode == 0block of shader-glsl.ts (and of picking/gsplat/shaders.ts).