Orkuncakilkaya
3f0bb07c16
sb7_pack / sb7_field are the one pack and unpack of the stream kinds' record (56 bits, least significant first: x 12, z 12, y 12 over the chunk's y span, scale 6, yaw 6, seed 4, wind 4, read as a low and a high word), which the bake and the game both import; stream_emit_baked decodes a prefix of it. layer_chunks_begin / layer_chunk_put / layer_chunk_drop keep a fixed layer (trees, boulders, stones: 12-byte records) as a slab per resident chunk in its instance list, an n x n index made at load, the list re-uploaded at most once a frame. Nothing calls them yet: behaviour unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
60 lines
3.4 KiB
Text
60 lines
3.4 KiB
Text
# stream_baked.ludic — a stream filled from baked chunks instead of generated ones (plan 26 of
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# maroon-lake). The bake stores every instance of a kind once per 64 m chunk, at full density and in a
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# shuffled order, so a distance band draws a PREFIX of it: a nearer band holds everything a farther one
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# does. The stream kinds' records are 7 bytes (below); the fixed layers' 12 (layer_chunks.ludic).
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# the stream's cells laid on the baked chunks' grid: `size` metres from the corner (ox, oz)
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export function stream_set_grid(s: Stream, ox: float, oz: float) -> void {
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s.ox = ox
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s.oz = oz
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}
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# ---- the stream kinds' 7-byte record (the one pack and unpack both the bake and the game use) ----
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# 56 bits, least significant first, bytes little-endian: x 12 (1/4096 of the chunk), z 12, y 12 (over
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# the chunk's y span: y_base + v / 4095 * y_span), scale 6 (lo + v / 63 * (hi - lo)), yaw 6 (v / 64 of a
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# turn), seed 4 (v / 15), wind 4 (v / 15). Read as a low word (bytes 0-3) and a high one (4-6), so no
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# field needs a 64-bit int.
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const SB7_REC: int = 7
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# one record's fields (already quantized) written at `at` in `out`
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export function sb7_pack(out: []byte, at: int, x: int, z: int, y: int, scale: int, yaw: int, seed: int, wind: int) -> void {
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let lo = (x & 4095) | ((z & 4095) << 12) | ((y & 255) << 24)
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let hi = ((y >> 8) & 15) | ((scale & 63) << 4) | ((yaw & 63) << 10) | ((seed & 15) << 16) | ((wind & 15) << 20)
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out[at] = lo & 255; out[at + 1] = (lo >> 8) & 255; out[at + 2] = (lo >> 16) & 255; out[at + 3] = (lo >> 24) & 255
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out[at + 4] = hi & 255; out[at + 5] = (hi >> 8) & 255; out[at + 6] = (hi >> 16) & 255
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}
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# field k of the record at `at` (0 x, 1 z, 2 y, 3 scale, 4 yaw, 5 seed, 6 wind), as its integer
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export function sb7_field(recs: pointer, at: int, k: int) -> int {
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let lo = recs[at] | (recs[at + 1] << 8) | (recs[at + 2] << 16) | ((recs[at + 3] & 255) << 24)
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let hi = recs[at + 4] | (recs[at + 5] << 8) | (recs[at + 6] << 16)
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if k == 0 { return lo & 4095 }
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if k == 1 { return (lo >> 12) & 4095 }
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if k == 2 { return ((lo >> 24) & 255) | ((hi & 15) << 8) }
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if k == 3 { return (hi >> 4) & 63 }
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if k == 4 { return (hi >> 10) & 63 }
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if k == 5 { return (hi >> 16) & 15 }
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return (hi >> 20) & 15
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}
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# the first `keep` 7-byte records of a stream kind's chunk emitted into the chunk being filled
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export function stream_emit_baked(render3d_st: mut Render3dState, s: Stream, recs: pointer, count: int, keep: int, x0: float, z0: float, y_base: float, y_span: float, lo: float, hi: float) -> void {
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let n = min(keep, count)
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let span = s.size / 4096.0
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for i in 0 .. n {
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let o = i * SB7_REC
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let x = x0 + float(sb7_field(recs, o, 0)) * span
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let z = z0 + float(sb7_field(recs, o, 1)) * span
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let y = y_base + float(sb7_field(recs, o, 2)) / 4095.0 * y_span
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let scale = lo + float(sb7_field(recs, o, 3)) / 63.0 * (hi - lo)
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let yaw = float(sb7_field(recs, o, 4)) * (2.0 * PI / 64.0)
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stream_emit(render3d_st, s, x, y, z, scale, yaw, float(sb7_field(recs, o, 5)) / 15.0, float(sb7_field(recs, o, 6)) / 15.0)
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}
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}
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# how many of a chunk's records a band keeps: all at band 0, then the share each band out had of the
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# generated density (the caller's table), rounded so a band is never empty where the chunk is not
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export function stream_band_keep(count: int, share: float) -> int {
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if count == 0 { return 0 }
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return max(1, min(count, int(float(count) * share + 0.5)))
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}
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