"""The world the painter looks at: a procedural, multi-scale grassy landscape. Units are metres. x runs to screen right, y away from the viewer, z up. Every field is a pure function of world position, evaluated band-limited at the spacing the current zoom needs (min_wl), so the same world can be looked at from 30 px/m down to 0.3 px/m without anything changing identity. The scene: a small stream winding along a valley floor, a grassy cut bank on its far side with hummocks along the lip, a meadow slope above, and rolling grassland hills beyond. Wetness collects in low ground; grazing shortens the sward; tussock colonies form where it is wet and lightly grazed. """ import numpy as np from dataclasses import dataclass, field from .noise import fbm, value_noise # grass species: height of the sward (m), tuft spacing (m), tuft width (m), # tussock fraction, stiffness (how straight blades stand), seedhead fraction SPECIES = { # h spacing width tussock stiff seedheads "turf": (0.08, 0.07, 0.06, 0.00, 0.8, 0.00), "meadow": (0.35, 0.10, 0.10, 0.05, 0.6, 0.10), "hay": (0.60, 0.10, 0.10, 0.02, 0.5, 0.25), "tussock": (0.45, 0.16, 0.22, 0.45, 0.4, 0.05), "sedge": (0.50, 0.12, 0.16, 0.30, 0.7, 0.02), } @dataclass class World: seed: int = 1 species: str = "meadow" moisture: float = 0.5 # 0 dry .. 1 wet (shifts hue green<->straw, sedge in hollows) grazing: float = 0.2 # 0 ungrazed .. 1 close-cropped wind: float = 0.3 # 0 calm .. 1 strong (lean + combing) wind_dir: float = 1.0 # +1 blows to screen right, -1 to the left season_dead: float = 0.05 # base fraction of straw (dead) blades relief: float = 1.0 # scales regional hills hummock: float = 0.3 # amplitude (m) of the 2-6 m hummocks water_level: float = 0.0 # ----- geometry -------------------------------------------------------------- def channel(self, x): """Stream centre line y_c(x) and half width.""" s = self.seed yc = (5.0 * np.sin(x / 37.0 + s) + 2.0 * np.sin(x / 11.0 + 2 * s) + 60.0 * np.sin(x / 420.0 + 0.3 * s)) return yc, 1.6 def height(self, x, y, min_wl=0.0): s = self.seed yc, hw = self.channel(x) d = y - yc # signed distance-ish to the stream (m); >0 = far side ad = np.abs(d) # regional hills, rising away from the valley floor reg = 38.0 * self.relief * fbm(x, y, 900.0, 4, 0.5, seed=s + 3, min_wl=min_wl) valley = 0.035 * self.relief * np.minimum(ad, 900.0) + 12.0 * self.relief * (1 - np.exp(-ad / 150.0)) z = 1.2 + valley + reg * np.clip(ad / 120.0, 0, 1) # spurs and gullies (100-300 m), ridged so hill flanks read as planes from afar rid = 1.0 - np.abs(fbm(x, y, 260.0, 3, 0.5, seed=s + 5, min_wl=min_wl)) z = z + 8.0 * self.relief * (rid - 0.5) * np.clip(ad / 60.0, 0, 1) # meadow undulation (swells of a few tens of metres) z = z + 1.6 * fbm(x, y, 40.0, 3, 0.5, seed=s + 7, min_wl=min_wl) # hummocks, 2-6 m hum = fbm(x, y, 6.0, 3, 0.55, seed=s + 11, min_wl=min_wl) z = z + self.hummock * hum # tussock micro-relief (0.4-1 m), only where tussocks grow tus = self.tussockness(x, y) mic = fbm(x, y, 1.2, 2, 0.5, seed=s + 13, min_wl=min_wl) z = z + 0.12 * tus * np.maximum(mic, -0.2) # the cut bank: a terrace step at the channel edge, ragged along its length rag = 0.5 * fbm(x, y, 3.0, 3, 0.5, seed=s + 17, min_wl=min_wl) bank_w = 1.6 + 0.8 * value_noise(x / 9.0, 0.5, s + 19) t = np.clip((ad - hw - rag * 0.6) / bank_w, 0, 1) step = t * t * (3 - 2 * t) bed = self.water_level - 0.35 z = bed + (z - bed) * step return z def normal(self, x, y, min_wl=0.0, eps=None): if eps is None: eps = max(0.02, min_wl * 0.5) z0 = self.height(x, y, min_wl) zx = (self.height(x + eps, y, min_wl) - z0) / eps zy = (self.height(x, y + eps, min_wl) - z0) / eps n = np.stack([-zx, -zy, np.ones_like(zx)]) return n / np.linalg.norm(n, axis=0) # ----- ecology --------------------------------------------------------------- def wetness(self, x, y): """0..1: wet in low ground near the stream and in patchy flushes.""" yc, hw = self.channel(x) ad = np.abs(y - yc) near = np.exp(-np.maximum(ad - hw, 0) / 12.0) patch = 0.5 + 0.5 * fbm(x, y, 30.0, 3, 0.5, seed=self.seed + 31) return np.clip((0.15 + 0.35 * self.moisture) * near + 0.5 * (patch - 0.5) + 1.1 * (self.moisture - 0.5) + 0.45, 0, 1) def tussockness(self, x, y): sp = SPECIES[self.species] colony = 0.5 + 0.5 * fbm(x, y, 12.0, 3, 0.5, seed=self.seed + 37) yc, hw = self.channel(x) wet = np.exp(-np.maximum(np.abs(y - yc) - hw, 0) / 15.0) v = sp[3] + 0.5 * wet * (1 - self.grazing) * (colony - 0.35) return np.clip(v * (1.0 - 0.6 * self.grazing), 0, 1) def dead(self, x, y): """Fraction of straw blades: dry ridges, grazing, season.""" w = self.wetness(x, y) patch = fbm(x, y, 18.0, 3, 0.5, seed=self.seed + 41) return np.clip(self.season_dead + 1.0 * (0.5 - w) + 0.35 * patch + 0.2 * self.grazing, 0, 1) def clump(self, x, y): """0..1 clumpiness at 0.3-2 m: grass grows in clumps with low gaps between; the taller crowns catch the light. At mid distance the clump is the mark.""" c = fbm(x, y, 1.6, 3, 0.55, seed=self.seed + 47) return np.clip(0.5 + 0.9 * c, 0, 1) def sheen(self, x, y): """Wind combing: long bands across the wind, lit where blades bend toward you.""" return fbm(x * 0.35, y * 1.4, 8.0, 3, 0.5, seed=self.seed + 53) def material(self, x, y): """-1..1 ground masses at 10-80 m, independent of light: drier knolls and trampled/grazed patches read lighter, wet flushes and lush growth darker.""" big = fbm(x, y, 45.0, 3, 0.5, seed=self.seed + 71) dry = 0.5 - self.wetness(x, y) return np.clip(0.8 * big + 0.8 * dry, -1, 1) def sward_height(self, x, y): """Local blade height (m).""" sp = SPECIES[self.species] h = sp[0] * (1.0 - 0.75 * self.grazing) patch = fbm(x, y, 5.0, 3, 0.5, seed=self.seed + 43) tus = self.tussockness(x, y) cl = self.clump(x, y) return np.maximum(0.03, h * (1 + 0.35 * patch) * (1 + 0.6 * tus) * (0.75 + 0.5 * cl))