diff options
Diffstat (limited to 'src/extras/shaders/gl3/metalroughuniform.frag')
-rw-r--r-- | src/extras/shaders/gl3/metalroughuniform.frag | 123 |
1 files changed, 88 insertions, 35 deletions
diff --git a/src/extras/shaders/gl3/metalroughuniform.frag b/src/extras/shaders/gl3/metalroughuniform.frag index cccd31b52..f4bad0a00 100644 --- a/src/extras/shaders/gl3/metalroughuniform.frag +++ b/src/extras/shaders/gl3/metalroughuniform.frag @@ -66,11 +66,6 @@ uniform vec4 baseColor; uniform float metalness; uniform float roughness; -// Roughness -> mip level mapping -uniform float maxT = 0.939824; -uniform float mipLevels = 11.0; -uniform float mipOffset = 5.0; - // Exposure correction uniform float exposure = 0.0; // Gamma correction @@ -78,6 +73,25 @@ uniform float gamma = 2.2; #pragma include light.inc.frag +int mipLevelCount(const in samplerCube cube) +{ + int baseSize = textureSize(cube, 0).x; + int nMips = int(log2(float(baseSize>0 ? baseSize : 1))) + 1; + return nMips; +} + +float remapRoughness(const in float roughness) +{ + // As per page 14 of + // http://www.frostbite.com/wp-content/uploads/2014/11/course_notes_moving_frostbite_to_pbr.pdf + // we remap the roughness to give a more perceptually linear response + // of "bluriness" as a function of the roughness specified by the user. + // r = roughness^2 + const float maxSpecPower = 999999.0; + const float minRoughness = sqrt(2.0 / (maxSpecPower + 2)); + return max(roughness * roughness, minRoughness); +} + mat3 calcWorldSpaceToTangentSpaceMatrix(const in vec3 wNormal, const in vec4 wTangent) { // Make the tangent truly orthogonal to the normal by using Gram-Schmidt. @@ -98,32 +112,42 @@ mat3 calcWorldSpaceToTangentSpaceMatrix(const in vec3 wNormal, const in vec4 wTa return worldToTangentMatrix; } -float roughnessToMipLevel(float roughness) -{ - // HACK: Improve the roughness -> mip level mapping for roughness map from substace painter - // TODO: Use mathematica or similar to improve this mapping more generally - roughness = 0.75 + (1.7 * (roughness - 0.5)); - return (mipLevels - 1.0 - mipOffset) * (1.0 - (1.0 - roughness) / maxT); -} - -// Helper function to map from linear roughness value to non-linear alpha (shininess) -float roughnessToAlpha(const in float roughness) +float alphaToMipLevel(float alpha) { - // Constants to control how to convert from roughness [0,1] to - // shininess (alpha) [minAlpha, maxAlpha] using a power law with - // a power of 1 / rho. - const float minAlpha = 1.0; - const float maxAlpha = 1024.0; - const float rho = 3.0; - - return minAlpha + (maxAlpha - minAlpha) * (1.0 - pow(roughness, 1.0 / rho)); + float specPower = 2.0 / (alpha * alpha) - 2.0; + + // We use the mip level calculation from Lys' default power drop, which in + // turn is a slight modification of that used in Marmoset Toolbag. See + // https://docs.knaldtech.com/doku.php?id=specular_lys for details. + // For now we assume a max specular power of 999999 which gives + // maxGlossiness = 1. + const float k0 = 0.00098; + const float k1 = 0.9921; + float glossiness = (pow(2.0, -10.0 / sqrt(specPower)) - k0) / k1; + + // TODO: Optimize by doing this on CPU and set as + // uniform int envLight.specularMipLevels say (if present in shader). + // Lookup the number of mips in the specular envmap + int mipLevels = mipLevelCount(envLight.specular); + + // Offset of smallest miplevel we should use (corresponds to specular + // power of 1). I.e. in the 32x32 sized mip. + const float mipOffset = 5.0; + + // The final factor is really 1 - g / g_max but as mentioned above g_max + // is 1 by definition here so we can avoid the division. If we make the + // max specular power for the spec map configurable, this will need to + // be handled properly. + float mipLevel = (mipLevels - 1.0 - mipOffset) * (1.0 - glossiness); + return mipLevel; } -float normalDistribution(const in vec3 n, const in vec3 h, const in float roughness) +float normalDistribution(const in vec3 n, const in vec3 h, const in float alpha) { - // Blinn-Phong approximation - float alpha = roughnessToAlpha(roughness); - return (alpha + 2.0) / (2.0 * 3.14159) * pow(max(dot(n, h), 0.0), alpha); + // Blinn-Phong approximation - see + // http://graphicrants.blogspot.co.uk/2013/08/specular-brdf-reference.html + float specPower = 2.0 / (alpha * alpha) - 2.0; + return (specPower + 2.0) / (2.0 * 3.14159) * pow(max(dot(n, h), 0.0), specPower); } vec3 fresnelFactor(const in vec3 color, const in float cosineFactor) @@ -171,7 +195,7 @@ vec3 pbrModel(const in int lightIndex, const in vec3 wView, const in vec3 baseColor, const in float metalness, - const in float roughness) + const in float alpha) { // Calculate some useful quantities vec3 n = wNormal; @@ -228,7 +252,7 @@ vec3 pbrModel(const in int lightIndex, vec3 specularFactor = vec3(0.0); if (sDotN > 0.0) { specularFactor = specularModel(F0, sDotH, sDotN, vDotN, n, h); - specularFactor *= normalDistribution(n, h, roughness); + specularFactor *= normalDistribution(n, h, alpha); } vec3 specularColor = lights[lightIndex].color; vec3 specular = specularColor * specularFactor; @@ -241,7 +265,7 @@ vec3 pbrIblModel(const in vec3 wNormal, const in vec3 wView, const in vec3 baseColor, const in float metalness, - const in float roughness) + const in float alpha) { // Calculate reflection direction of view vector about surface normal // vector in world space. This is used in the fragment shader to sample @@ -265,7 +289,31 @@ vec3 pbrIblModel(const in vec3 wNormal, vec3 F0 = mix(dielectricColor, baseColor, metalness); vec3 specularFactor = specularModel(F0, lDotH, lDotN, vDotN, n, h); - float lod = roughnessToMipLevel(roughness); + // As per page 14 of + // http://www.frostbite.com/wp-content/uploads/2014/11/course_notes_moving_frostbite_to_pbr.pdf + // we remap the roughness to give a more perceptually linear response + // of "bluriness" as a function of the roughness specified by the user. + // r = roughness^2 + float lod = alphaToMipLevel(alpha); +//#define DEBUG_SPECULAR_LODS +#ifdef DEBUG_SPECULAR_LODS + if (lod > 7.0) + return vec3(1.0, 0.0, 0.0); + else if (lod > 6.0) + return vec3(1.0, 0.333, 0.0); + else if (lod > 5.0) + return vec3(1.0, 1.0, 0.0); + else if (lod > 4.0) + return vec3(0.666, 1.0, 0.0); + else if (lod > 3.0) + return vec3(0.0, 1.0, 0.666); + else if (lod > 2.0) + return vec3(0.0, 0.666, 1.0); + else if (lod > 1.0) + return vec3(0.0, 0.0, 1.0); + else if (lod > 0.0) + return vec3(1.0, 0.0, 1.0); +#endif vec3 specularSkyColor = textureLod(envLight.specular, l, lod).rgb; vec3 specular = specularSkyColor * specularFactor; @@ -287,23 +335,28 @@ void main() { vec3 cLinear = vec3(0.0); + // Remap roughness for a perceptually more linear correspondence + float alpha = remapRoughness(roughness); + + + vec3 wNormal = normalize(worldNormal); vec3 worldView = normalize(eyePosition - worldPosition); for (int i = 0; i < envLightCount; ++i) { - cLinear += pbrIblModel(worldNormal, + cLinear += pbrIblModel(wNormal, worldView, baseColor.rgb, metalness, - roughness); + alpha); } for (int i = 0; i < lightCount; ++i) { cLinear += pbrModel(i, worldPosition, - worldNormal, + wNormal, worldView, baseColor.rgb, metalness, - roughness); + alpha); } // Apply exposure correction |