Class PunctualLightUniforms

One shaded pipeline's light-set uniforms: the five locations, and the CPU mirror that keeps a scene without point or spot lights emitting no GL call at all (R-17, 2026-08-09).

Shared by LitProgram and gl-standard.ts's StandardProgram because the upload is not a per-pipeline decision — the two stages consume the identical SceneLights arrays through the identical GLSL chunk, and a class each would be two places for the skip rule to drift apart.

The skip rule, and why it is byte-identity rather than an optimisation

#count starts at 0, which is what GL initializes an int uniform to. A frame whose SceneLights.punctualCount is 0 while the mirror is 0 therefore uploads nothing — not the count, not the four arrays — so a scene lit by a directional light and an ambient term issues byte-for-byte the GL sequence it issued before this class existed. The same technique as R-15's bool encode switch and R-38's permissive layer mask; the third confirmation that seeding a CPU mirror at GL's own initial value is how a feature is added to this backend for free.

When the count is non-zero the whole array is uploaded, dead tail included, rather than a live sub-range: uniform3fv over the record's own Float32Array copies nothing on the way (the reason @fourjs/render packs those arrays as typed arrays), and a sub-range upload would need the srcOffset/srcLength overloads this backend's hand-written GL surface deliberately does not carry.