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Diffstat (limited to 'indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl')
| -rw-r--r-- | indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl b/indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl new file mode 100644 index 0000000000..9e6c853015 --- /dev/null +++ b/indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl @@ -0,0 +1,141 @@ +/** + * @file class1/deferred/genbrdflut.glsl + * + * $LicenseInfo:firstyear=2022&license=viewerlgpl$ + * Second Life Viewer Source Code + * Copyright (C) 2022, Linden Research, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; + * version 2.1 of the License only. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + * + * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA + * $/LicenseInfo$ + */ + +/* Taken from Sascha Willem's Vulkan GLTF refernce implementation +MIT License + +Copyright (c) 2018 Sascha Willems + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. +*/ + +/*[EXTRA_CODE_HERE]*/ + +VARYING vec2 vary_uv; + +out vec4 outColor; + +#define NUM_SAMPLES 1024u + +const float PI = 3.1415926536; + +// Based omn http://byteblacksmith.com/improvements-to-the-canonical-one-liner-glsl-rand-for-opengl-es-2-0/ +float random(vec2 co) +{ + float a = 12.9898; + float b = 78.233; + float c = 43758.5453; + float dt= dot(co.xy ,vec2(a,b)); + float sn= mod(dt,3.14); + return fract(sin(sn) * c); +} + +vec2 hammersley2d(uint i, uint N) +{ + // Radical inverse based on http://holger.dammertz.org/stuff/notes_HammersleyOnHemisphere.html + uint bits = (i << 16u) | (i >> 16u); + bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u); + bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u); + bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u); + bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u); + float rdi = float(bits) * 2.3283064365386963e-10; + return vec2(float(i) /float(N), rdi); +} + +// Based on http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_slides.pdf +vec3 importanceSample_GGX(vec2 Xi, float roughness, vec3 normal) +{ + // Maps a 2D point to a hemisphere with spread based on roughness + float alpha = roughness * roughness; + float phi = 2.0 * PI * Xi.x + random(normal.xz) * 0.1; + float cosTheta = sqrt((1.0 - Xi.y) / (1.0 + (alpha*alpha - 1.0) * Xi.y)); + float sinTheta = sqrt(1.0 - cosTheta * cosTheta); + vec3 H = vec3(sinTheta * cos(phi), sinTheta * sin(phi), cosTheta); + + // Tangent space + vec3 up = abs(normal.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0); + vec3 tangentX = normalize(cross(up, normal)); + vec3 tangentY = normalize(cross(normal, tangentX)); + + // Convert to world Space + return normalize(tangentX * H.x + tangentY * H.y + normal * H.z); +} + +// Geometric Shadowing function +float G_SchlicksmithGGX(float dotNL, float dotNV, float roughness) +{ + float k = (roughness * roughness) / 2.0; + float GL = dotNL / (dotNL * (1.0 - k) + k); + float GV = dotNV / (dotNV * (1.0 - k) + k); + return GL * GV; +} + +vec2 BRDF(float NoV, float roughness) +{ + // Normal always points along z-axis for the 2D lookup + const vec3 N = vec3(0.0, 0.0, 1.0); + vec3 V = vec3(sqrt(1.0 - NoV*NoV), 0.0, NoV); + + vec2 LUT = vec2(0.0); + for(uint i = 0u; i < NUM_SAMPLES; i++) { + vec2 Xi = hammersley2d(i, NUM_SAMPLES); + vec3 H = importanceSample_GGX(Xi, roughness, N); + vec3 L = 2.0 * dot(V, H) * H - V; + + float dotNL = max(dot(N, L), 0.0); + float dotNV = max(dot(N, V), 0.0); + float dotVH = max(dot(V, H), 0.0); + float dotNH = max(dot(H, N), 0.0); + + if (dotNL > 0.0) { + float G = G_SchlicksmithGGX(dotNL, dotNV, roughness); + float G_Vis = (G * dotVH) / (dotNH * dotNV); + float Fc = pow(1.0 - dotVH, 5.0); + LUT += vec2((1.0 - Fc) * G_Vis, Fc * G_Vis); + } + } + return LUT / float(NUM_SAMPLES); +} + +void main() +{ + outColor = vec4(BRDF(vary_uv.s, 1.0-vary_uv.t), 0.0, 1.0); +} |