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annotate semicongine/noise.nim @ 840:44ec744fbedc

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did: package restructuring according to nimble recommendation for libraries
author Sam <sam@basx.dev>
date Sat, 02 Dec 2023 22:23:29 +0700
parents
children c66503386e8b
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44ec744fbedc did: package restructuring according to nimble recommendation for libraries
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1 import hashes
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2 import math
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3
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4 import ./core/vector
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5
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6
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7 proc randomGradient(pos: Vec2f, seed: int32 = 0): Vec2f =
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8 let randomAngle: float32 = TAU * (float32(int(hash((pos.x, pos.y, seed)))) / float32(high(int)))
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9 return newVec2f(cos(randomAngle), sin(randomAngle))
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10
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11 proc interpolate(a: float32, b: float32, weight: float32): float32 =
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12 # with Smootherstep
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13 (b - a) * ((weight * (weight * 6.0 - 15.0) + 10.0) * weight * weight * weight) + a;
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14
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15 proc perlin*(pos: Vec2f, seed: int32 = 0): float32 =
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16 let
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17 # grid coordinates around target point
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18 topleft = newVec2f(trunc(pos.x), trunc(pos.y))
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19 topright = topleft + newVec2f(1, 0)
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20 bottomleft = topleft + newVec2f(0, 1)
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21 bottomright = topleft + newVec2f(1, 1)
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22 # products for weights
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23 topleft_dot = topleft.randomGradient(seed).dot((pos - topleft))
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24 topright_dot = topright.randomGradient(seed).dot((pos - topright))
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25 bottomleft_dot = bottomleft.randomGradient(seed).dot((pos - bottomleft))
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26 bottomright_dot = bottomright.randomGradient(seed).dot((pos - bottomright))
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27 xinterpol = pos.x - topleft.x
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28 yinterpol = pos.y - topleft.y
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29
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30 return interpolate(
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31 interpolate(topleft_dot, bottomleft_dot, yinterpol),
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32 interpolate(topright_dot, bottomright_dot, yinterpol),
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33 xinterpol
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34 )