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February 25, 2016 07:31
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| /* | |
| optimized-ggx.glsl | |
| This file describes several optimizations you can make when creating a GGX shader. | |
| AUTHOR: John Hable | |
| LICENSE: | |
| This is free and unencumbered software released into the public domain. | |
| Anyone is free to copy, modify, publish, use, compile, sell, or | |
| distribute this software, either in source code form or as a compiled | |
| binary, for any purpose, commercial or non-commercial, and by any | |
| means. | |
| In jurisdictions that recognize copyright laws, the author or authors | |
| of this software dedicate any and all copyright interest in the | |
| software to the public domain. We make this dedication for the benefit | |
| of the public at large and to the detriment of our heirs and | |
| successors. We intend this dedication to be an overt act of | |
| relinquishment in perpetuity of all present and future rights to this | |
| software under copyright law. | |
| 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 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. | |
| For more information, please refer to <http://unlicense.org/> | |
| */ | |
| float G1V(float dotNV, float k) | |
| { | |
| return 1.0f/(dotNV*(1.0f-k)+k); | |
| } | |
| float LightingFuncGGX_REF(vec3 N, vec3 V, vec3 L, float roughness, float F0) | |
| { | |
| float alpha = roughness*roughness; | |
| vec3 H = normalize(V+L); | |
| float dotNL = saturate(dot(N,L)); | |
| float dotNV = saturate(dot(N,V)); | |
| float dotNH = saturate(dot(N,H)); | |
| float dotLH = saturate(dot(L,H)); | |
| float F, D, vis; | |
| // D | |
| float alphaSqr = alpha*alpha; | |
| float pi = 3.14159f; | |
| float denom = dotNH * dotNH *(alphaSqr-1.0) + 1.0f; | |
| D = alphaSqr/(pi * denom * denom); | |
| // F | |
| float dotLH5 = pow(1.0f-dotLH,5); | |
| F = F0 + (1.0-F0)*(dotLH5); | |
| // V | |
| float k = alpha/2.0f; | |
| vis = G1V(dotNL,k)*G1V(dotNV,k); | |
| float specular = dotNL * D * F * vis; | |
| return specular; | |
| } | |
| float LightingFuncGGX_OPT1(vec3 N, vec3 V, vec3 L, float roughness, float F0) | |
| { | |
| float alpha = roughness*roughness; | |
| vec3 H = normalize(V+L); | |
| float dotNL = saturate(dot(N,L)); | |
| float dotLH = saturate(dot(L,H)); | |
| float dotNH = saturate(dot(N,H)); | |
| float F, D, vis; | |
| // D | |
| float alphaSqr = alpha*alpha; | |
| float pi = 3.14159f; | |
| float denom = dotNH * dotNH *(alphaSqr-1.0) + 1.0f; | |
| D = alphaSqr/(pi * denom * denom); | |
| // F | |
| float dotLH5 = pow(1.0f-dotLH,5); | |
| F = F0 + (1.0-F0)*(dotLH5); | |
| // V | |
| float k = alpha/2.0f; | |
| vis = G1V(dotLH,k)*G1V(dotLH,k); | |
| float specular = dotNL * D * F * vis; | |
| return specular; | |
| } | |
| float LightingFuncGGX_OPT2(vec3 N, vec3 V, vec3 L, float roughness, float F0) | |
| { | |
| float alpha = roughness*roughness; | |
| vec3 H = normalize(V+L); | |
| float dotNL = saturate(dot(N,L)); | |
| float dotLH = saturate(dot(L,H)); | |
| float dotNH = saturate(dot(N,H)); | |
| float F, D, vis; | |
| // D | |
| float alphaSqr = alpha*alpha; | |
| float pi = 3.14159f; | |
| float denom = dotNH * dotNH *(alphaSqr-1.0) + 1.0f; | |
| D = alphaSqr/(pi * denom * denom); | |
| // F | |
| float dotLH5 = pow(1.0f-dotLH,5); | |
| F = F0 + (1.0-F0)*(dotLH5); | |
| // V | |
| float k = alpha/2.0f; | |
| float k2 = k*k; | |
| float invK2 = 1.0f-k2; | |
| vis = rcp(dotLH*dotLH*invK2 + k2); | |
| float specular = dotNL * D * F * vis; | |
| return specular; | |
| } | |
| vec2 LightingFuncGGX_FV(float dotLH, float roughness) | |
| { | |
| float alpha = roughness*roughness; | |
| // F | |
| float F_a, F_b; | |
| float dotLH5 = pow(1.0f-dotLH,5); | |
| F_a = 1.0f; | |
| F_b = dotLH5; | |
| // V | |
| float vis; | |
| float k = alpha/2.0f; | |
| float k2 = k*k; | |
| float invK2 = 1.0f-k2; | |
| vis = rcp(dotLH*dotLH*invK2 + k2); | |
| return vec2(F_a*vis,F_b*vis); | |
| } | |
| float LightingFuncGGX_D(float dotNH, float roughness) | |
| { | |
| float alpha = roughness*roughness; | |
| float alphaSqr = alpha*alpha; | |
| float pi = 3.14159f; | |
| float denom = dotNH * dotNH *(alphaSqr-1.0) + 1.0f; | |
| float D = alphaSqr/(pi * denom * denom); | |
| return D; | |
| } | |
| float LightingFuncGGX_OPT3(vec3 N, vec3 V, vec3 L, float roughness, float F0) | |
| { | |
| vec3 H = normalize(V+L); | |
| float dotNL = saturate(dot(N,L)); | |
| float dotLH = saturate(dot(L,H)); | |
| float dotNH = saturate(dot(N,H)); | |
| float D = LightingFuncGGX_D(dotNH,roughness); | |
| vec2 FV_helper = LightingFuncGGX_FV(dotLH,roughness); | |
| float FV = F0*FV_helper.x + (1.0f-F0)*FV_helper.y; | |
| float specular = dotNL * D * FV; | |
| return specular; | |
| } |
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