tower / files / test / desert.test.ts
desert.test.ts
| 1 | import { readFileSync } from 'node:fs' |
| 2 | import { describe, expect, it } from 'vitest' |
| 3 | import { RADIUS_M } from '../src/canon/constants.js' |
| 4 | import { compileWorld } from '../src/terrain/compile.js' |
| 5 | import { BENCH_STEP_M, CORRIDOR_M, terrace } from '../src/terrain/desert.js' |
| 6 | import { prepare } from '../src/terrain/field.js' |
| 7 | import { MATERIALS, materialsAt } from '../src/terrain/tile.js' |
| 8 | import { type Desert, parseWorld } from '../src/world/schema.js' |
| 9 | |
| 10 | const world = parseWorld(JSON.parse(readFileSync('content/world.json', 'utf8'))) |
| 11 | const cw = compileWorld(world) |
| 12 | const rt = prepare(cw) |
| 13 | const reach = world.features.find((f): f is Desert => f.kind === 'desert')! |
| 14 | const d = cw.deserts.find((x) => x.id === reach.id)! |
| 15 | const ground = (z: number, a: number): number => rt.sample(a / RADIUS_M, z, 2).h |
| 16 | |
| 17 | /** Every cell of the desert's grid, as (index, z, a). */ |
| 18 | function* cells(step = 3): Generator<[number, number, number]> { |
| 19 | const { grid } = d |
| 20 | for (let i = 0; i < grid.nz; i += step) { |
| 21 | for (let j = 0; j < grid.na; j += step) { |
| 22 | yield [i * grid.na + j, grid.z0 + i * grid.cell, grid.a0 + j * grid.cell] |
| 23 | } |
| 24 | } |
| 25 | } |
| 26 | |
| 27 | describe('the terrace profile', () => { |
| 28 | it('stays within its range and climbs in the number of tiers asked for', () => { |
| 29 | for (const terraces of [1, 3, 5]) { |
| 30 | expect(terrace(0, terraces)).toBe(0) |
| 31 | expect(terrace(1, terraces)).toBeCloseTo(1, 6) |
| 32 | // As many rises as there are tiers, each with a flat bench before the next. |
| 33 | let risers = 0, climbing = false |
| 34 | let prev = terrace(0, terraces) |
| 35 | for (let p = 0; p <= 1; p += 0.002) { |
| 36 | const v = terrace(p, terraces) |
| 37 | expect(v).toBeGreaterThanOrEqual(prev - 1e-9) |
| 38 | const rising = v - prev > 1e-6 |
| 39 | if (rising && !climbing) risers++ |
| 40 | climbing = rising |
| 41 | prev = v |
| 42 | } |
| 43 | expect(risers).toBe(terraces) |
| 44 | } |
| 45 | }) |
| 46 | |
| 47 | it('leaves the tops flat: most of a tier is a level bench', () => { |
| 48 | let flat = 0, n = 0 |
| 49 | for (let p = 0; p <= 1; p += 0.001) { |
| 50 | const slope = Math.abs(terrace(p + 0.001, 3) - terrace(p, 3)) / 0.001 |
| 51 | if (slope < 0.05) flat++ |
| 52 | n++ |
| 53 | } |
| 54 | expect(flat / n).toBeGreaterThan(0.55) |
| 55 | }) |
| 56 | }) |
| 57 | |
| 58 | describe('the Dry Reach as compiled', () => { |
| 59 | it('lays out the plateaus over about the coverage asked for', () => { |
| 60 | let inside = 0, rock = 0 |
| 61 | for (const [k] of cells()) { |
| 62 | if (d.inside[k]! < 0.9) continue |
| 63 | inside++ |
| 64 | if (d.plateau[k]! > 0.5) rock++ |
| 65 | } |
| 66 | expect(inside).toBeGreaterThan(1000) |
| 67 | expect(rock / inside).toBeGreaterThan(reach.plateaus.coverage * 0.6) |
| 68 | expect(rock / inside).toBeLessThan(reach.plateaus.coverage * 1.4) |
| 69 | }) |
| 70 | |
| 71 | it('cuts washes that run: a network, deep where it has gathered', () => { |
| 72 | let cutCells = 0, inside = 0, deepest = 0 |
| 73 | for (const [k] of cells()) { |
| 74 | if (d.inside[k]! < 0.9) continue |
| 75 | inside++ |
| 76 | if (d.cut[k]! > 3) cutCells++ |
| 77 | deepest = Math.max(deepest, d.cut[k]!) |
| 78 | } |
| 79 | // Channels, not a lowered desert: a minority of the ground, and tens of metres deep. |
| 80 | expect(cutCells / inside).toBeGreaterThan(0.05) |
| 81 | expect(cutCells / inside).toBeLessThan(0.6) |
| 82 | expect(deepest).toBeGreaterThan(15) |
| 83 | expect(deepest).toBeLessThan(60) |
| 84 | }) |
| 85 | |
| 86 | it('lays the salt pans Tower asked for, spaced out, in the low ground', () => { |
| 87 | expect(d.pans).toHaveLength(reach.pastWater.saltPans) |
| 88 | for (let i = 0; i < d.pans.length; i++) { |
| 89 | for (let j = i + 1; j < d.pans.length; j++) { |
| 90 | const p = d.pans[i]!, q = d.pans[j]! |
| 91 | expect(Math.hypot(p.z - q.z, p.a - q.a)).toBeGreaterThan(p.radiusM * 2) |
| 92 | } |
| 93 | } |
| 94 | }) |
| 95 | |
| 96 | it('makes a pan floor dead flat, and steps the ground around it in benches', () => { |
| 97 | const pan = d.pans[0]! |
| 98 | const level = ground(pan.z, pan.a) |
| 99 | for (const off of [-pan.radiusM * 0.5, -pan.radiusM * 0.25, pan.radiusM * 0.25, pan.radiusM * 0.5]) { |
| 100 | expect(Math.abs(ground(pan.z + off, pan.a) - level)).toBeLessThan(2) |
| 101 | expect(Math.abs(ground(pan.z, pan.a + off) - level)).toBeLessThan(2) |
| 102 | } |
| 103 | // Outside it, the ground stands at the levels a lake would have left: heights cluster |
| 104 | // on multiples of the bench step above the floor, rather than climbing smoothly. |
| 105 | let onStep = 0, n = 0 |
| 106 | for (let off = pan.radiusM * 1.1; off < pan.radiusM + 900; off += 25) { |
| 107 | const above = ground(pan.z + off, pan.a) - level |
| 108 | if (above <= 0) continue |
| 109 | const away = Math.abs(above / BENCH_STEP_M - Math.round(above / BENCH_STEP_M)) |
| 110 | if (away < 0.22) onStep++ |
| 111 | n++ |
| 112 | } |
| 113 | expect(n).toBeGreaterThan(10) |
| 114 | expect(onStep / n).toBeGreaterThan(0.5) |
| 115 | }) |
| 116 | |
| 117 | it('keeps its rock off the rivers Tower had already routed', () => { |
| 118 | const trunk = cw.rivers.find((r) => r.id === 'the-long-water')! |
| 119 | for (let i = 0; i < trunk.line.s.length; i += 40) { |
| 120 | const z = trunk.line.pts[2 * i]!, a = trunk.line.pts[2 * i + 1]! |
| 121 | const { grid } = d |
| 122 | const gi = Math.round((z - grid.z0) / grid.cell) |
| 123 | if (gi < 0 || gi >= grid.nz) continue |
| 124 | const gj = ((Math.round((a - grid.a0) / grid.cell) % grid.na) + grid.na) % grid.na |
| 125 | expect(d.plateau[gi * grid.na + gj]!).toBeLessThan(0.05) |
| 126 | } |
| 127 | }) |
| 128 | |
| 129 | it('claims rock where the rock is, and salt on the pans', () => { |
| 130 | const out = new Float32Array(MATERIALS.length) |
| 131 | const pan = d.pans[0]! |
| 132 | materialsAt(rt.sample(pan.a / RADIUS_M, pan.z, 2), 0, out) |
| 133 | expect(out[MATERIALS.indexOf('salt')]!).toBeGreaterThan(0.8) |
| 134 | expect(out[MATERIALS.indexOf('desert')]!).toBeLessThan(0.2) |
| 135 | |
| 136 | // A mesa top: bare rock, and no sand claim on it. |
| 137 | let mesa: [number, number] | null = null |
| 138 | for (const [k, z, a] of cells()) if (!mesa && d.plateau[k]! > 0.98) mesa = [z, a] |
| 139 | materialsAt(rt.sample(mesa![1] / RADIUS_M, mesa![0], 2), 0, out) |
| 140 | expect(out[MATERIALS.indexOf('rock')]! + out[MATERIALS.indexOf('sandstone')]!).toBeGreaterThan(0.8) |
| 141 | }) |
| 142 | |
| 143 | it('stands a dune field up in the sand, crest to trough about the height asked for', () => { |
| 144 | let sandy: [number, number] | null = null |
| 145 | for (const [k, z, a] of cells()) { |
| 146 | if (!sandy && d.sand[k]! > 0.95 && d.plateau[k]! < 0.02 && d.cut[k]! < 1) sandy = [z, a] |
| 147 | } |
| 148 | expect(sandy).not.toBeNull() |
| 149 | // Across the wind — the dunes' crests run across it, so a transect along it crosses them. |
| 150 | let lo = Infinity, hi = -Infinity |
| 151 | for (let i = 0; i < 40; i++) { |
| 152 | const h = ground(sandy![0] + i * 60, sandy![1]) |
| 153 | lo = Math.min(lo, h); hi = Math.max(hi, h) |
| 154 | } |
| 155 | expect(hi - lo).toBeGreaterThan(reach.dunes.heightM * 0.3) |
| 156 | expect(hi - lo).toBeLessThan(reach.dunes.heightM * 2.5) |
| 157 | }) |
| 158 | |
| 159 | it('costs about a second of the compile, and no seam where theta wraps', () => { |
| 160 | const { grid } = d |
| 161 | expect(grid.cell * grid.na).toBeCloseTo(2 * Math.PI * RADIUS_M, 3) |
| 162 | for (const z of [152_000, 170_000, 200_000]) { |
| 163 | const before = ground(z, -30) |
| 164 | const after = ground(z, 2 * Math.PI * RADIUS_M - 30) |
| 165 | expect(Math.abs(after - before)).toBeLessThan(0.01) |
| 166 | } |
| 167 | expect(CORRIDOR_M).toBeGreaterThan(1000) |
| 168 | }) |
| 169 | }) |