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terrain.py
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terrain.py
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"""Noise generators and other basic terrain functions."""
import time
import numpy as np
from numba import njit, prange
import opensimplex as osi
import cfg
# pylint: disable=not-an-iterable
# pylint: disable=line-too-long
@njit(cache=True, parallel=True, nogil=True)
def sample_noise(verts, perm, pgi, n_roughness=1, n_strength=0.2, radius=1):
"""Sample a simplex noise for given vertices."""
elevations = np.ones(len(verts), dtype=np.float64)
rough_verts = verts * n_roughness
for v in prange(len(rough_verts)):
elevations[v] = osi.noise3d(rough_verts[v][0], rough_verts[v][1], rough_verts[v][2], perm, pgi)
# print(" Pre-elevations:")
# print(elevations)
# print(" min:", np.amin(elevations))
# print(" max:", np.amax(elevations))
# NOTE: Adding 1 to elevation moves negative values in the 0-1 range.
# Multiplying by *0.5 drags any values > 1 back into the 0-1 range.
return (elevations 1) * 0.5 * n_strength * radius # NOTE: I'm not sure if multiplying by the radius is the proper thing to do in my next implementation.
# return elevations
def sample_octaves(verts, elevations, perm, pgi, n_octaves=1, n_init_roughness=1.5, n_init_strength=0.4, n_roughness=2.0, n_persistence=0.5, world_radius=1.0):
"""Sample octaves of noise and combine them together."""
if elevations is None:
elevations = np.zeros(len(verts), dtype=np.float64)
n_freq = n_init_roughness # Frequency
n_amp = n_init_strength # Amplitude
# In my separate-sampling experiment, rough/strength pairs of (1.6, 0.4) (5, 0.2) and (24, 0.02) were good for 3 octaves
# The final 3 results were added and then multiplied by 0.4
for i in range(n_octaves):
print(f"\r Octave {i 1}..", flush =True, end ='')
time_start = time.perf_counter()
elevations = sample_noise(verts, perm, pgi, n_freq / world_radius, n_amp / world_radius, world_radius)
n_freq *= n_roughness
n_amp *= n_persistence
time_end = time.perf_counter()
print(f" {time_end - time_start :.5f} sec")
# time_nmin = time.perf_counter()
emin = np.amin(elevations)
# time_nmax = time.perf_counter()
emax = np.amax(elevations)
# time_end = time.perf_counter()
# print(f" Time to find numpy min: {time_nmax - time_nmin :.5f} sec")
# print(f" Time to find numpy max: {time_end - time_nmax :.5f} sec")
print(" Combined octaves min:", emin)
print(" Combined octaves max:", emax)
return elevations
@njit(cache=True, parallel=True, nogil=True)
def make_bool_elevation_mask(height, mask_elevation):
"""Create a mask from an array of heights and a given elevation."""
# NOTE: Some other functions may not like that a dtype of bool_ stores "True" or "False" instead of numbers.
# Keep an eye on that. We can always switch to int8 or uint8 and store 0 or 1 if we need to.
mask = np.zeros(len(height), dtype=np.bool_)
for h in prange(len(height)):
if height[h] <= mask_elevation:
mask[h] = 1
return mask