sightlineUsesPackedDepth

True when sightline receivers read the cube through a plain samplerCube (no hardware depth-compare) — the depth pass then packs window depth into an RGBA8 color cube via earth.worldwind.render.program.PackedDepthProgram. Sampling a real DEPTH_COMPONENT texture through a plain sampler is driver-dependent — Adreno 512 returns ~8-bit quantized depth, collapsing the sightline's 1/d mapping into kilometre buckets — while RGBA8 color reads are exact on every GPU.