pub const REFERENCE_PX: u32 = 230_400;Expand description
The render target the attractor’s sample density is anchored to: 640x360, 230 400 pixels.
The attractor’s trail grid is surface-sized, so its deposit spreads over
whatever the target holds and a flat count therefore falls in density as the
target grows — 0.651 particles per pixel per frame here, 0.072 at 1080p, which
is the whole of the “it just looks like Leviathan upscaled” verdict. This is
the size whose density is already accepted, so it is where
attractor_budget resolves to exactly the tier’s own anchor.
The numerator is the grid’s texels before quantization —
GridScale::texels of the target’s pixels, which at GridScale::FULL is
the target’s pixel count exactly — so a field drawn at a fraction of the
target is sampled at the density this reference names rather than
over-sampled for texels it does not have (ADR-0245). What it still does not
count is the grid’s 128-texel rounding, a bounded difference either way —
1.07x here and at 720p, 0.95x at 1080p, 1.00x at a capped 4K — named
because the deposit lands per texel.