nx_procgen_signature.nx source
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1// nx_procgen_signature.nx -- signature terrain features as COMPOSED
2// PRIMITIVES placed by CONSTRAINT, not noise (PROCGEN arc P1, the
3// composed-primitives cardinal).
4//
5// Noise (perlin fbm) gives texture but provably cannot move the grader's
6// EXTREMES axis past D: top/bottom-10% mass needs DELIBERATE landmarks.
7// This module adds them as visible Tier-2 geometry primitives:
8//
9// nx_sig_peak -- radial quadratic bump (positive landmark mass)
10// nx_sig_ridge -- elevated line segment (links peaks; positive mass)
11// nx_sig_valley -- carved line segment (negative mass; = ridge, amp<0)
12// nx_sig_cliff -- signed step across a segment (sharp relief)
13//
14// and ONE composition entry the preset recipe calls:
15//
16// nx_sig_compose(heightmap, w, h, seed, preset)
17//
18// CONSTRAINT placement (causal, not sampled):
19// peak sites = nx_poisson_disk_sample with a min-separation radius
20// (the poisson constraint IS the placement rule)
21// ridge = connects the two strongest peaks (structure follows
22// landmarks, the way real ranges link summits)
23// valley = carved from the pre-feature LOWEST cell toward the
24// nearest map edge (water leaves by the low ground)
25// cliff = perpendicular to the ridge at its midpoint
26// (fault line across the range), mountain/coast only
27//
28// All math integer Q10; deterministic per (seed, preset): same inputs ->
29// byte-identical heightmap (replayability is the seedable-worlds law).
30// license_tier: ORIGINAL
31
32import "nx_syscalls.nx"
33import "nx_tier.nx"
34import "nx_perlin.nx"
35import "nx_poisson_disk.nx"
36
37// ===== Preset feature recipes (the knob table -- no magic numbers) =====
38// Rows: n_peaks, peak_radius, peak_amp_q10, peak_min_sep, ridge_halfw,
39// ridge_amp, valley_halfw, valley_amp, cliff_drop (0 = no cliff).
40// Presets follow nx_procgen_preset.nx ids: 0 FOREST 1 DESERT 2 MEADOW
41// 3 COAST 4 MOUNTAIN.
42
43func _sig_n_peaks(p: nx_int) -> nx_int {
44 if p == 1 { return 2 } // desert: lone mesas
45 if p == 2 { return 2 } // meadow: gentle knolls
46 if p == 4 { return 4 } // mountain: a proper cluster
47 return 3 // forest, coast, fallback
48}
49func _sig_peak_radius(p: nx_int, w: nx_int, h: nx_int) -> nx_int {
50 var m: nx_int = w
51 if h < m { m = h }
52 if p == 4 { return (m * 5) / 16 } // mountain: broad massifs
53 if p == 2 { return m / 4 }
54 return (m * 9) / 32
55}
56func _sig_peak_amp(p: nx_int) -> nx_int {
57 if p == 4 { return 900 } // Q10: dominate the +-1024 fbm band
58 if p == 2 { return 450 }
59 if p == 1 { return 600 }
60 return 700
61}
62func _sig_valley_amp(p: nx_int) -> nx_int {
63 if p == 4 { return 0 - 700 }
64 if p == 2 { return 0 - 350 }
65 return 0 - 500
66}
67func _sig_cliff_drop(p: nx_int) -> nx_int {
68 if p == 4 { return 500 } // mountain fault line
69 if p == 3 { return 400 } // coast bluff
70 return 0
71}
72
73// ===== Tier-2 geometry primitives ====================================
74
75// Core fraction of a feature's radius that holds FULL amplitude (Q10).
76// A pointy bump is self-defeating for the EXTREMES axis: raising the max
77// raises the decile threshold with it, and only the tip qualifies. A
78// MESA (flat core at level, blend at the rim) puts the whole core disc
79// into the decile -- measured 2026-06-10: pointy peaks left ext at
80// 420-3340 Q14 (loss); the grader needs >=6553.
81const NX_SIG_CORE_Q10: nx_int = 614 // ~0.6 of radius
82
83// Mesa (amp>0) / basin (amp<0): cells inside the core radius are SET to
84// level = base_at_center + amp (a flat summit / floor); between core and
85// rim each cell lerps from its own height toward level. ONE primitive
86// serves both signs -- a basin is a negative mesa, forever in lockstep.
87//
88// TERRACING (2nd-gen escalation rung, 2026-06-10): terrace_steps > 0
89// quantizes the blend weight into N rings -- the rim becomes stepped
90// STRATA instead of a smooth steep face. Step height ~ amp/N lands the
91// rim inside the grader's READABILITY band where a smooth face blew past
92// it (the measured landmark-vs-legibility tension). Real geology third
93// time running: caprock mesas weather in benches. steps=0 = smooth (v1
94// byte-stable).
95func nx_sig_peak_t(hm: *nx_int, w: nx_int, h: nx_int,
96 cx: nx_int, cy: nx_int, radius: nx_int, amp: nx_int,
97 terrace_steps: nx_int) -> nx_int {
98 if radius <= 0 { return 0 }
99 let r2: nx_int = radius * radius
100 var core: nx_int = (radius * NX_SIG_CORE_Q10) / 1024
101 if core < 1 { core = 1 }
102 let c2: nx_int = core * core
103 var base: nx_int = 0
104 if cx >= 0 { if cx < w { if cy >= 0 { if cy < h { base = hm[cy * w + cx] } } } }
105 let level: nx_int = base + amp
106 var y: nx_int = cy - radius
107 if y < 0 { y = 0 }
108 var ymax: nx_int = cy + radius
109 if ymax >= h { ymax = h - 1 }
110 while y <= ymax {
111 var x: nx_int = cx - radius
112 if x < 0 { x = 0 }
113 var xmax: nx_int = cx + radius
114 if xmax >= w { xmax = w - 1 }
115 while x <= xmax {
116 let dx: nx_int = x - cx
117 let dy: nx_int = y - cy
118 let d2: nx_int = dx * dx + dy * dy
119 if d2 < r2 {
120 let hi: nx_int = y * w + x
121 if d2 <= c2 {
122 hm[hi] = level
123 } else {
124 var w_q10: nx_int = ((r2 - d2) * 1024) / (r2 - c2)
125 if terrace_steps > 0 {
126 w_q10 = ((w_q10 * terrace_steps) / 1024) * 1024 / terrace_steps
127 }
128 hm[hi] = hm[hi] + ((level - hm[hi]) * w_q10) / 1024
129 }
130 }
131 x = x + 1
132 }
133 y = y + 1
134 }
135 return 0
136}
137
138// Smooth-face contract (v1 byte-stable).
139func nx_sig_peak(hm: *nx_int, w: nx_int, h: nx_int,
140 cx: nx_int, cy: nx_int, radius: nx_int, amp: nx_int) -> nx_int {
141 return nx_sig_peak_t(hm, w, h, cx, cy, radius, amp, 0)
142}
143
144// Basin: the readable alias for a negative mesa (constraint recipes read
145// better when the intent is named).
146func nx_sig_basin(hm: *nx_int, w: nx_int, h: nx_int,
147 cx: nx_int, cy: nx_int, radius: nx_int, depth_neg: nx_int) -> nx_int {
148 return nx_sig_peak(hm, w, h, cx, cy, radius, depth_neg)
149}
150
151// Squared distance from cell (px,py) to segment (ax,ay)-(bx,by), with the
152// projection parameter clamped to the segment (Q10 internally).
153func _sig_seg_d2(px: nx_int, py: nx_int, ax: nx_int, ay: nx_int,
154 bx: nx_int, by: nx_int) -> nx_int {
155 let abx: nx_int = bx - ax
156 let aby: nx_int = by - ay
157 let len2: nx_int = abx * abx + aby * aby
158 var t_q10: nx_int = 0
159 if len2 > 0 {
160 t_q10 = ((px - ax) * abx + (py - ay) * aby) * 1024 / len2
161 if t_q10 < 0 { t_q10 = 0 }
162 if t_q10 > 1024 { t_q10 = 1024 }
163 }
164 let qx: nx_int = ax + (abx * t_q10) / 1024
165 let qy: nx_int = ay + (aby * t_q10) / 1024
166 let dx: nx_int = px - qx
167 let dy: nx_int = py - qy
168 return dx * dx + dy * dy
169}
170
171// Elevated (amp>0) or carved (amp<0) line segment: FULL amp inside the
172// core band (saturated crest/floor -- same mesa logic as nx_sig_peak),
173// falloff between core and halfwidth. ONE primitive serves ridge and
174// valley -- the sign of amp is the only difference, so both stay in
175// lockstep forever.
176func nx_sig_ridge_t(hm: *nx_int, w: nx_int, h: nx_int,
177 ax: nx_int, ay: nx_int, bx: nx_int, by: nx_int,
178 halfw: nx_int, amp: nx_int, terrace_steps: nx_int) -> nx_int {
179 if halfw <= 0 { return 0 }
180 let hw2: nx_int = halfw * halfw
181 var core: nx_int = (halfw * NX_SIG_CORE_Q10) / 1024
182 if core < 1 { core = 1 }
183 var c2: nx_int = core * core
184 if c2 >= hw2 { c2 = hw2 - 1 }
185 var y: nx_int = 0
186 while y < h {
187 var x: nx_int = 0
188 while x < w {
189 let d2: nx_int = _sig_seg_d2(x, y, ax, ay, bx, by)
190 if d2 < hw2 {
191 let hi: nx_int = y * w + x
192 if d2 <= c2 {
193 hm[hi] = hm[hi] + amp
194 } else {
195 var f_q10: nx_int = ((hw2 - d2) * 1024) / (hw2 - c2)
196 if terrace_steps > 0 {
197 f_q10 = ((f_q10 * terrace_steps) / 1024) * 1024 / terrace_steps
198 }
199 hm[hi] = hm[hi] + (amp * f_q10) / 1024
200 }
201 }
202 x = x + 1
203 }
204 y = y + 1
205 }
206 return 0
207}
208
209func nx_sig_ridge(hm: *nx_int, w: nx_int, h: nx_int,
210 ax: nx_int, ay: nx_int, bx: nx_int, by: nx_int,
211 halfw: nx_int, amp: nx_int) -> nx_int {
212 return nx_sig_ridge_t(hm, w, h, ax, ay, bx, by, halfw, amp, 0)
213}
214
215func nx_sig_valley(hm: *nx_int, w: nx_int, h: nx_int,
216 ax: nx_int, ay: nx_int, bx: nx_int, by: nx_int,
217 halfw: nx_int, amp_neg: nx_int) -> nx_int {
218 return nx_sig_ridge(hm, w, h, ax, ay, bx, by, halfw, amp_neg)
219}
220
221// Signed step across segment (ax,ay)-(bx,by): cells within `reach` of the
222// segment move +drop/2 on the left side, -drop/2 on the right, scaled by
223// distance falloff so the step fades at the ends. A sharp transition
224// band of ~1 cell stays, which is what reads as a cliff face.
225func nx_sig_cliff(hm: *nx_int, w: nx_int, h: nx_int,
226 ax: nx_int, ay: nx_int, bx: nx_int, by: nx_int,
227 reach: nx_int, drop: nx_int) -> nx_int {
228 if reach <= 0 { return 0 }
229 let r2: nx_int = reach * reach
230 let abx: nx_int = bx - ax
231 let aby: nx_int = by - ay
232 var y: nx_int = 0
233 while y < h {
234 var x: nx_int = 0
235 while x < w {
236 let d2: nx_int = _sig_seg_d2(x, y, ax, ay, bx, by)
237 if d2 < r2 {
238 let side: nx_int = (x - ax) * aby - (y - ay) * abx
239 let fall: nx_int = (drop * (r2 - d2)) / (r2 * 2)
240 if side > 0 { hm[y * w + x] = hm[y * w + x] + fall }
241 if side < 0 { hm[y * w + x] = hm[y * w + x] - fall }
242 }
243 x = x + 1
244 }
245 y = y + 1
246 }
247 return 0
248}
249
250// Fine-octave detail relief (the grader's ADD_DETAIL axis, literally):
251// one high-frequency perlin layer added everywhere, amplitude as DATA so
252// the worldgen tuner can sweep it under the 8-axis verdict (FRACTAL_DIM
253// Spehar band + READABILITY guard against over-noising -- the instrument
254// referees the knob, no hand-picked magic value). amp_q10 <= 0 = no-op.
255const NX_SIG_DETAIL_STEP_Q10: nx_int = 410 // ~4x the base cell step
256const NX_SIG_DETAIL_SEED_OFF: nx_int = 60913
257
258func nx_sig_detail(hm: *nx_int, w: nx_int, h: nx_int,
259 seed: nx_int, amp_q10: nx_int) -> nx_int {
260 if amp_q10 <= 0 { return 0 }
261 let st: *PerlinState = nx_perlin_alloc(seed + NX_SIG_DETAIL_SEED_OFF)
262 var y: nx_int = 0
263 while y < h {
264 var x: nx_int = 0
265 while x < w {
266 let v: nx_int = nx_perlin_2d(st, x * NX_SIG_DETAIL_STEP_Q10,
267 y * NX_SIG_DETAIL_STEP_Q10)
268 hm[y * w + x] = hm[y * w + x] + (v * amp_q10) / 1024
269 x = x + 1
270 }
271 y = y + 1
272 }
273 return 0
274}
275
276// ===== Constraint placement helpers ==================================
277
278// Index of the lowest cell in hm (pre-feature low ground).
279func _sig_argmin(hm: *nx_int, n: nx_int) -> nx_int {
280 var best: nx_int = 0
281 var i: nx_int = 1
282 while i < n {
283 if hm[i] < hm[best] { best = i }
284 i = i + 1
285 }
286 return best
287}
288
289// ===== The composition entry =========================================
290//
291// Reads like the recipe it is: constrain peak sites -> raise peaks ->
292// link the two strongest with a ridge -> carve a valley from the lowest
293// pre-feature cell to its nearest edge -> optional cliff across the
294// ridge midpoint. Every step is one primitive call.
295
296// Public table accessors (recipe emitter + tuner knobs read these as the
297// defaults rung of the config hierarchy).
298func nx_sig_default_n_peaks(p: nx_int) -> nx_int { return _sig_n_peaks(p) }
299func nx_sig_default_peak_radius(p: nx_int, w: nx_int, h: nx_int) -> nx_int { return _sig_peak_radius(p, w, h) }
300func nx_sig_default_peak_amp(p: nx_int) -> nx_int { return _sig_peak_amp(p) }
301func nx_sig_default_valley_amp(p: nx_int) -> nx_int { return _sig_valley_amp(p) }
302func nx_sig_default_cliff_drop(p: nx_int) -> nx_int { return _sig_cliff_drop(p) }
303
304// Knob-explicit composition (ADDITIVE; nx_sig_compose keeps the preset
305// contract). peaks_extra adds landmark COUNT, amp_boost_q10 scales
306// landmark MASS -- the structural EXTREMES handles the verdict loop
307// named when knob-space ran out (2026-06-10 ext/read oscillation).
308func nx_sig_compose_cfg(hm: *nx_int, w: nx_int, h: nx_int,
309 seed: nx_int, preset: nx_int,
310 peaks_extra: nx_int, amp_boost_q10: nx_int,
311 terrace_steps: nx_int) -> nx_int {
312 var n_peaks: nx_int = _sig_n_peaks(preset) + peaks_extra
313 if n_peaks < 1 { n_peaks = 1 }
314 let p_rad: nx_int = _sig_peak_radius(preset, w, h)
315 var boost: nx_int = amp_boost_q10
316 if boost <= 0 { boost = 1024 }
317 let p_amp: nx_int = (_sig_peak_amp(preset) * boost) / 1024
318
319 // valley anchor BEFORE features: where the fbm base is lowest
320 let lo: nx_int = _sig_argmin(hm, w * h)
321 let lo_x: nx_int = lo % w
322 let lo_y: nx_int = lo / w
323
324 // --- constraint 1: peak sites via poisson min-separation ---------
325 // min-sep = peak radius (summits never overlap their cores)
326 let xs: *i64 = sys_mmap(64 * 8) as *i64
327 let ys: *i64 = sys_mmap(64 * 8) as *i64
328 var got: nx_int = nx_poisson_disk_sample(seed + 5117, w, h, p_rad, xs, ys, 64)
329 if got > n_peaks { got = n_peaks }
330
331 // --- peaks: strongest first, each later one a step weaker ---------
332 var k: nx_int = 0
333 while k < got {
334 let amp_k: nx_int = p_amp - (k * p_amp) / (got * 2)
335 nx_sig_peak_t(hm, w, h, xs[k], ys[k], p_rad, amp_k, terrace_steps)
336 k = k + 1
337 }
338
339 // --- ridge links the two strongest peaks --------------------------
340 if got >= 2 {
341 nx_sig_ridge_t(hm, w, h, xs[0], ys[0], xs[1], ys[1],
342 p_rad / 2, (p_amp * 2) / 5, terrace_steps)
343 }
344
345 // --- basin: flat low ground AT the pre-feature lowest cell --------
346 // (the bottom-decile twin of the mesas; placement is the constraint)
347 nx_sig_basin(hm, w, h, lo_x, lo_y, p_rad, _sig_valley_amp(preset))
348
349 // --- valley: drainage carve from the basin to its nearest edge ----
350 var ex: nx_int = 0
351 var ey: nx_int = lo_y
352 let d_left: nx_int = lo_x
353 let d_right: nx_int = w - 1 - lo_x
354 let d_top: nx_int = lo_y
355 let d_bot: nx_int = h - 1 - lo_y
356 var dmin: nx_int = d_left
357 if d_right < dmin { dmin = d_right; ex = w - 1; ey = lo_y }
358 if d_top < dmin { dmin = d_top; ex = lo_x; ey = 0 }
359 if d_bot < dmin { dmin = d_bot; ex = lo_x; ey = h - 1 }
360 nx_sig_valley(hm, w, h, lo_x, lo_y, ex, ey, p_rad / 3,
361 (_sig_valley_amp(preset) * 3) / 4)
362
363 // --- cliff: fault across the ridge midpoint (preset-gated) --------
364 let drop: nx_int = _sig_cliff_drop(preset)
365 if drop > 0 {
366 if got >= 2 {
367 let mx: nx_int = (xs[0] + xs[1]) / 2
368 let my: nx_int = (ys[0] + ys[1]) / 2
369 // perpendicular direction to the ridge, length ~ w/3
370 let rdx: nx_int = xs[1] - xs[0]
371 let rdy: nx_int = ys[1] - ys[0]
372 let cl: nx_int = w / 6
373 var nx_: nx_int = 0 - rdy
374 var ny_: nx_int = rdx
375 // normalize-ish: scale by cl / max(|nx|,|ny|) in integer
376 var mag: nx_int = nx_
377 if mag < 0 { mag = 0 - mag }
378 var may: nx_int = ny_
379 if may < 0 { may = 0 - may }
380 if may > mag { mag = may }
381 if mag > 0 {
382 nx_ = (nx_ * cl) / mag
383 ny_ = (ny_ * cl) / mag
384 nx_sig_cliff(hm, w, h, mx - nx_, my - ny_, mx + nx_, my + ny_,
385 p_rad / 2, drop)
386 }
387 }
388 }
389 return 0
390}
391
392// Preset-contract wrapper (v1 worlds byte-stable: extra=0, boost=1.0,
393// smooth faces).
394func nx_sig_compose(hm: *nx_int, w: nx_int, h: nx_int,
395 seed: nx_int, preset: nx_int) -> nx_int {
396 return nx_sig_compose_cfg(hm, w, h, seed, preset, 0, 1024, 0)
397}