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add reaction_diffusion

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Justin Lin 2022-01-24 18:05:37 +08:00
parent 9320125b42
commit dd632d5845
1 changed files with 96 additions and 0 deletions
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src/experimental/reaction_diffusion.scad Normal file
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function init(x, y, n, ix, iy, in) =
let(
half_x = floor(x / 2),
half_y = floor(y / 2),
half_ix = floor(ix / 2),
half_iy = floor(iy / 2),
lowx = half_x - half_ix,
highx = half_x + half_ix,
lowy = half_y - half_iy,
highy = half_y + half_iy
)
[
for(j = [0:y - 1])
[
for(i = [0:x - 1])
i >= lowx && i < highx && j >= lowy && j < highy ?
in : n
]
];
function gray_scott(u, v, feel, kill, Du, Dv, space_x, space_y) =
let(
nuv = [
for(y = [0:space_y - 1])
let(
uy = (y + 1 + space_y) % space_y,
ly = (y - 1 + space_y) % space_y,
row_u = u[y],
row_v = v[y],
row_uu = u[uy],
row_ul = u[ly],
row_vu = v[uy],
row_vl = v[ly]
)
[
for(x = [0:space_x - 1])
let(
cu = row_u[x],
cv = row_v[x],
rx = (x + 1 + space_x) % space_x,
lx = (x - 1 + space_x) % space_x,
reaction = cu * (cv ^ 2)
)
[
Du * (row_uu[x] + row_u[rx] + row_ul[x] + row_u[lx] - 4 * cu) - reaction + feel * (1 - cu),
Dv * (row_vu[x] + row_v[rx] + row_vl[x] + row_v[lx] - 4 * cv) + reaction - (feel + kill) * cv
]
]
]
)
[
u + [for(row = nuv) [for(uv = row) uv[0]]],
v + [for(row = nuv) [for(uv = row) uv[1]]]
];
function _reaction_diffusion(feel, kill, generation, u, v, Du, Dv, space_x, space_y) =
generation == 0 ? [u, v] :
let(nuv = gray_scott(u, v, feel, kill, Du, Dv, space_x, space_y))
_reaction_diffusion(feel, kill, generation - 1, nuv[0], nuv[1], Du, Dv, space_x, space_y);
function reaction_diffusion(
feel, kill, generation, space_size = [50, 50], init_size = [10, 10], init_u = 0.5, init_v = 0.25, Du = 0.2, Dv = 0.1) =
let(
u = init(space_size[0], space_size[1], 1, init_size[0], init_size[1], init_u),
v = init(space_size[0], space_size[1], 0, init_size[0], init_size[1], init_v)
)
_reaction_diffusion(feel, kill, generation, u, v, Du, Dv, space_size[0], space_size[1]);
/*
use <surface/sf_thicken.scad>;
use <experimental/reaction_diffusion.scad>;
feel = 0.04;
kill = 0.06;
generation = 1000;
thickness = 0.5;
altitude_scale = 10;
space_size = [50, 50];
init_size = [10, 10];
uv = reaction_diffusion(feel, kill, generation, space_size, init_size);
leng_y = len(uv[0]);
leng_x = len(uv[0][0]);
points = [
for(y = [0:leng_y - 1])
[
for(x = [0:leng_x - 1])
[x, y, uv[0][y][x] * altitude_scale]
]
];
sf_thicken(points, thickness);
*/