25 lines
912 B
Python
25 lines
912 B
Python
# coding: utf-8
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# original alg from https://github.com/assimp/assimp/issues/4573
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# Copyright (C) 2023 Ilia Kurochkin <brothermechanic@yandex.com>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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__version__ = '0.1'
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import math
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def shiny_to_rough(shininess):
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''' convert shiny to roughness '''
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a, b = -1.0, 2.0
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c = (shininess / 100.0) - 1.0
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D = math.pow(b, 2) - (4 * a * c)
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roughness = (-b + math.sqrt(D)) / (2 * a)
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return max(roughness, 0)
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