35 lines
1.2 KiB
HLSL
35 lines
1.2 KiB
HLSL
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "/Engine/Public/Platform.ush"
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#define MEDIUMP_FLT_MAX 65504.0
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#define MEDIUMP_FLT_MIN 0.00006103515625
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// Taken from https://gist.github.com/romainguy/a2e9208f14cae37c579448be99f78f25
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// Modified by Epic Games, Inc. To account for premultiplied light color and code style rules.
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half D_GGX_Mobile(half Roughness, float NoH)
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{
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// Walter et al. 2007, "Microfacet Models for Refraction through Rough Surfaces"
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float OneMinusNoHSqr = 1.0 - NoH * NoH;
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half a = Roughness * Roughness;
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half n = NoH * a;
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half p = a / (OneMinusNoHSqr + n * n);
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half d = (1.0 / PI) * p * p;
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// clamp to avoid overlfow in a bright env
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return min(d, 2048.0);
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} |