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Approximate specularity / glossiness in metallicRoughness materials 

Before, models (of traditional lighting models) with specularity/glossiness would be completely flat when exported to metallicRoughness. These changes approximate glossiness (as an inverse of roughness, with specular intensity as a multiplier) both reading from gltf2 and writing to gltf2.
pull/1503/head
Daniel Hritzkiv 2017-10-19 12:30:32 -04:00
parent a898c1f2d1
commit 89358458f0
No known key found for this signature in database
GPG Key ID: D1D19875679D5CBF
2 changed files with 39 additions and 2 deletions
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34
code/glTF2Exporter.cpp
View File

@ -434,7 +434,29 @@ void glTF2Exporter::ExportMaterials()
m->pbrMetallicRoughness.metallicFactor = 0;
}
mat->Get(AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_ROUGHNESS_FACTOR, m->pbrMetallicRoughness.roughnessFactor);
// get roughness if source is gltf2 file
if (mat->Get(AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_ROUGHNESS_FACTOR, m->pbrMetallicRoughness.roughnessFactor) != AI_SUCCESS) {
// otherwise, try to derive and convert from specular + shininess values
aiColor4D specularColor;
ai_real shininess;
if (
mat->Get(AI_MATKEY_COLOR_SPECULAR, specularColor) == AI_SUCCESS &&
mat->Get(AI_MATKEY_SHININESS, shininess) == AI_SUCCESS
) {
// convert specular color to luminance
float specularIntensity = specularColor[0] * 0.2125 + specularColor[1] * 0.7154 + specularColor[2] * 0.0721;
float roughnessFactor = 1 - std::sqrt(shininess / 1000);
roughnessFactor = std::powf(roughnessFactor, 2);
roughnessFactor = std::min(std::max(roughnessFactor, 0.0f), 1.0f);
// low specular intensity values should produce a rough material even if shininess is high.
roughnessFactor = 1 - (roughnessFactor * specularIntensity);
m->pbrMetallicRoughness.roughnessFactor = roughnessFactor;
}
}
GetMatTex(mat, m->normalTexture, aiTextureType_NORMALS);
GetMatTex(mat, m->occlusionTexture, aiTextureType_LIGHTMAP);
@ -470,9 +492,17 @@ void glTF2Exporter::ExportMaterials()
PbrSpecularGlossiness pbrSG;
mat->Get(AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS_GLOSSINESS_FACTOR, pbrSG.glossinessFactor);
GetMatColor(mat, pbrSG.diffuseFactor, AI_MATKEY_COLOR_DIFFUSE);
GetMatColor(mat, pbrSG.specularFactor, AI_MATKEY_COLOR_SPECULAR);
if (mat->Get(AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS_GLOSSINESS_FACTOR, pbrSG.glossinessFactor) != AI_SUCCESS) {
float shininess;
if (mat->Get(AI_MATKEY_SHININESS, shininess)) {
pbrSG.glossinessFactor = shininess / 1000;
}
}
GetMatTex(mat, pbrSG.diffuseTexture, aiTextureType_DIFFUSE);
GetMatTex(mat, pbrSG.specularGlossinessTexture, aiTextureType_SPECULAR);

7
code/glTF2Importer.cpp
View File

@ -234,9 +234,13 @@ void glTF2Importer::ImportMaterials(glTF2::Asset& r)
SetMaterialTextureProperty(embeddedTexIdxs, r, mat.pbrMetallicRoughness.baseColorTexture, aimat, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_BASE_COLOR_TEXTURE);
SetMaterialTextureProperty(embeddedTexIdxs, r, mat.pbrMetallicRoughness.metallicRoughnessTexture, aimat, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_METALLICROUGHNESS_TEXTURE);
aimat->AddProperty(&mat.pbrMetallicRoughness.metallicFactor, 1, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_METALLIC_FACTOR);
aimat->AddProperty(&mat.pbrMetallicRoughness.roughnessFactor, 1, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_ROUGHNESS_FACTOR);
float roughnessAsShininess = (1 - mat.pbrMetallicRoughness.roughnessFactor) * 1000;
aimat->AddProperty(&roughnessAsShininess, 1, AI_MATKEY_SHININESS);
SetMaterialTextureProperty(embeddedTexIdxs, r, mat.normalTexture, aimat, aiTextureType_NORMALS);
SetMaterialTextureProperty(embeddedTexIdxs, r, mat.occlusionTexture, aimat, aiTextureType_LIGHTMAP);
SetMaterialTextureProperty(embeddedTexIdxs, r, mat.emissiveTexture, aimat, aiTextureType_EMISSIVE);
@ -255,6 +259,9 @@ void glTF2Importer::ImportMaterials(glTF2::Asset& r)
aimat->AddProperty(&mat.pbrSpecularGlossiness.isPresent, 1, AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS);
SetMaterialColorProperty(r, pbrSG.diffuseFactor, aimat, AI_MATKEY_COLOR_DIFFUSE);
SetMaterialColorProperty(r, pbrSG.specularFactor, aimat, AI_MATKEY_COLOR_SPECULAR);
float glossinessAsShininess = pbrSG.glossinessFactor * 1000.0f;
aimat->AddProperty(&glossinessAsShininess, 1, AI_MATKEY_SHININESS);
aimat->AddProperty(&pbrSG.glossinessFactor, 1, AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS_GLOSSINESS_FACTOR);
SetMaterialTextureProperty(embeddedTexIdxs, r, pbrSG.diffuseTexture, aimat, aiTextureType_DIFFUSE);