From 200bf8df7a6879b5c0840cba0b9d620f6b4221b1 Mon Sep 17 00:00:00 2001
From: diharaw <shredhead94@gmail.com>
Date: Wed, 29 Sep 2021 17:05:17 +0100
Subject: [PATCH 1/7] Added gltf2 KHR_materials_volume import support.

---
 code/AssetLib/glTF2/glTF2Asset.h      | 16 ++++++++++++++++
 code/AssetLib/glTF2/glTF2Asset.inl    | 21 +++++++++++++++++++++
 code/AssetLib/glTF2/glTF2Importer.cpp | 10 ++++++++++
 include/assimp/material.h             | 17 +++++++++++++++++
 4 files changed, 64 insertions(+)

diff --git a/code/AssetLib/glTF2/glTF2Asset.h b/code/AssetLib/glTF2/glTF2Asset.h
index 9a50ede99..fb3100b2c 100644
--- a/code/AssetLib/glTF2/glTF2Asset.h
+++ b/code/AssetLib/glTF2/glTF2Asset.h
@@ -49,6 +49,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *   KHR_materials_sheen full
  *   KHR_materials_clearcoat full
  *   KHR_materials_transmission full
+ *   KHR_materials_volume full
  */
 #ifndef GLTF2ASSET_H_INC
 #define GLTF2ASSET_H_INC
@@ -713,6 +714,7 @@ const vec3 defaultEmissiveFactor = { 0, 0, 0 };
 const vec4 defaultDiffuseFactor = { 1, 1, 1, 1 };
 const vec3 defaultSpecularFactor = { 1, 1, 1 };
 const vec3 defaultSheenFactor = { 0, 0, 0 };
+const vec3 defaultAttenuationColor = { 1, 1, 1 };
 
 struct TextureInfo {
     Ref<Texture> texture;
@@ -777,6 +779,16 @@ struct MaterialTransmission {
     float transmissionFactor = 0.f;
 };
 
+struct MaterialVolume {
+    float thicknessFactor = 0.f;
+    TextureInfo thicknessTexture;
+    float attenuationDistance = 0.f;
+    vec3 attenuationColor;
+
+    MaterialVolume() { SetDefaults(); }
+    void SetDefaults();
+};
+
 //! The material appearance of a primitive.
 struct Material : public Object {
     //PBR metallic roughness properties
@@ -803,6 +815,9 @@ struct Material : public Object {
     //extension: KHR_materials_transmission
     Nullable<MaterialTransmission> materialTransmission;
 
+    //extension: KHR_materials_volume
+    Nullable<MaterialVolume> materialVolume;
+    
     //extension: KHR_materials_unlit
     bool unlit;
 
@@ -1091,6 +1106,7 @@ public:
         bool KHR_materials_sheen;
         bool KHR_materials_clearcoat;
         bool KHR_materials_transmission;
+        bool KHR_materials_volume;
         bool KHR_draco_mesh_compression;
         bool FB_ngon_encoding;
         bool KHR_texture_basisu;
diff --git a/code/AssetLib/glTF2/glTF2Asset.inl b/code/AssetLib/glTF2/glTF2Asset.inl
index 4832995cc..ff71ff53b 100644
--- a/code/AssetLib/glTF2/glTF2Asset.inl
+++ b/code/AssetLib/glTF2/glTF2Asset.inl
@@ -1215,6 +1215,19 @@ inline void Material::Read(Value &material, Asset &r) {
             }
         }
 
+        if (r.extensionsUsed.KHR_materials_volume) {
+            if (Value *curMaterialVolume = FindObject(*extensions, "KHR_materials_volume")) {
+                MaterialVolume volume;
+
+                ReadMember(*curMaterialVolume, "thicknessFactor", volume.thicknessFactor);
+                ReadTextureProperty(r, *curMaterialVolume, "thicknessTexture", volume.thicknessTexture);
+                ReadMember(*curMaterialVolume, "attenuationDistance", volume.attenuationDistance);
+                ReadMember(*curMaterialVolume, "attenuationColor", volume.attenuationColor);
+
+                this->materialVolume = Nullable<MaterialVolume>(volume);
+            }
+        }
+
         unlit = nullptr != FindObject(*extensions, "KHR_materials_unlit");
     }
 }
@@ -1260,6 +1273,13 @@ inline void MaterialSheen::SetDefaults() {
     sheenRoughnessFactor = 0.f;
 }
 
+inline void MaterialVolume::SetDefaults() {
+    //KHR_materials_volume properties
+    thicknessFactor = 0.f;
+    attenuationDistance = INFINITY;
+    SetVector(attenuationColor, defaultAttenuationColor);
+}
+
 namespace {
 
 template <int N>
@@ -1931,6 +1951,7 @@ inline void Asset::ReadExtensionsUsed(Document &doc) {
     CHECK_EXT(KHR_materials_sheen);
     CHECK_EXT(KHR_materials_clearcoat);
     CHECK_EXT(KHR_materials_transmission);
+    CHECK_EXT(KHR_materials_volume);
     CHECK_EXT(KHR_draco_mesh_compression);
     CHECK_EXT(KHR_texture_basisu);
 
diff --git a/code/AssetLib/glTF2/glTF2Importer.cpp b/code/AssetLib/glTF2/glTF2Importer.cpp
index 6c92bdc87..136b01d07 100644
--- a/code/AssetLib/glTF2/glTF2Importer.cpp
+++ b/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -341,6 +341,16 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
             SetMaterialTextureProperty(embeddedTexIdxs, r, transmission.transmissionTexture, aimat, AI_MATKEY_TRANSMISSION_TEXTURE);
         }
 
+        // KHR_materials_volume
+        if (mat.materialVolume.isPresent) {
+            MaterialVolume &volume = mat.materialVolume.value;
+
+            aimat->AddProperty(&volume.thicknessFactor, 1, AI_MATKEY_VOLUME_THICKNESS_FACTOR);
+            SetMaterialTextureProperty(embeddedTexIdxs, r, volume.thicknessTexture, aimat, AI_MATKEY_VOLUME_THICKNESS_TEXTURE);
+            aimat->AddProperty(&volume.attenuationDistance, 1, AI_MATKEY_VOLUME_ATTENUATION_DISTANCE);
+            SetMaterialColorProperty(r, volume.attenuationColor, aimat, AI_MATKEY_VOLUME_ATTENUATION_COLOR);
+        }
+
         return aimat;
     } catch (...) {
         delete aimat;
diff --git a/include/assimp/material.h b/include/assimp/material.h
index 250ad90d5..2373185fc 100644
--- a/include/assimp/material.h
+++ b/include/assimp/material.h
@@ -318,6 +318,12 @@ enum aiTextureType {
     */
     aiTextureType_TRANSMISSION = 21,
 
+    /** Volume
+    * Simulates transmission through the surface
+    * May include further information such as wall thickness
+    */
+    aiTextureType_VOLUME = 22,
+
     /** Unknown texture
      *
      *  A texture reference that does not match any of the definitions
@@ -1028,6 +1034,17 @@ extern "C" {
 // Multiplied by AI_MATKEY_TRANSMISSION_FACTOR
 #define AI_MATKEY_TRANSMISSION_TEXTURE aiTextureType_TRANSMISSION, 0
 
+// Volume
+// ------------
+// https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_volume
+// Base percentage of light transmitted through the surface. 0.0 = Opaque, 1.0 = Fully transparent
+#define AI_MATKEY_VOLUME_THICKNESS_FACTOR "$mat.volume.thicknessFactor", 0, 0
+// Texture defining percentage of light transmitted through the surface.
+// Multiplied by AI_MATKEY_THICKNESS_FACTOR
+#define AI_MATKEY_VOLUME_THICKNESS_TEXTURE aiTextureType_VOLUME, 0
+#define AI_MATKEY_VOLUME_ATTENUATION_DISTANCE "$mat.volume.attenuationDistance", 0, 0
+#define AI_MATKEY_VOLUME_ATTENUATION_COLOR "$mat.volume.attenuationColor", 0, 0
+
 // Emissive
 // --------
 #define AI_MATKEY_USE_EMISSIVE_MAP "$mat.useEmissiveMap", 0, 0

From d3276de47da869417b1a619640f534d90e66a6dc Mon Sep 17 00:00:00 2001
From: diharaw <shredhead94@gmail.com>
Date: Thu, 30 Sep 2021 08:10:02 +0100
Subject: [PATCH 2/7] Added gltf2 KHR_materials_volume write support.

---
 code/AssetLib/glTF2/glTF2AssetWriter.h   |  1 +
 code/AssetLib/glTF2/glTF2AssetWriter.inl | 26 ++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/code/AssetLib/glTF2/glTF2AssetWriter.h b/code/AssetLib/glTF2/glTF2AssetWriter.h
index 8244a14b9..9be3fdf0c 100644
--- a/code/AssetLib/glTF2/glTF2AssetWriter.h
+++ b/code/AssetLib/glTF2/glTF2AssetWriter.h
@@ -49,6 +49,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *   KHR_materials_sheen: full
  *   KHR_materials_clearcoat: full
  *   KHR_materials_transmission: full
+ *   KHR_materials_volume: full
  */
 #ifndef GLTF2ASSETWRITER_H_INC
 #define GLTF2ASSETWRITER_H_INC
diff --git a/code/AssetLib/glTF2/glTF2AssetWriter.inl b/code/AssetLib/glTF2/glTF2AssetWriter.inl
index 115cdf903..03b8476dc 100644
--- a/code/AssetLib/glTF2/glTF2AssetWriter.inl
+++ b/code/AssetLib/glTF2/glTF2AssetWriter.inl
@@ -474,6 +474,28 @@ namespace glTF2 {
             }
         }
 
+        if (m.materialVolume.isPresent) {
+            Value materialVolume(rapidjson::Type::kObjectType);
+
+            MaterialVolume &volume = m.materialVolume.value;
+
+            if (volume.thicknessFactor != 0.f) {
+                WriteFloat(materialVolume, volume.thicknessFactor, "thicknessFactor", w.mAl);
+            }
+
+            WriteTex(materialVolume, volume.thicknessTexture, "thicknessTexture", w.mAl);
+
+            if (volume.attenuationDistance != INFINITY) {
+                WriteFloat(materialVolume, volume.attenuationDistance, "attenuationDistance", w.mAl);
+            }
+
+            WriteVec(materialVolume, volume.attenuationColor, "attenuationColor", defaultAttenuationColor, w.mAl);
+
+            if (!materialVolume.ObjectEmpty()) {
+                exts.AddMember("KHR_materials_volume", materialVolume, w.mAl);
+            }
+        }
+
         if (!exts.ObjectEmpty()) {
             obj.AddMember("extensions", exts, w.mAl);
         }
@@ -890,6 +912,10 @@ namespace glTF2 {
                 exts.PushBack(StringRef("KHR_materials_transmission"), mAl);
             }
 
+            if (this->mAsset.extensionsUsed.KHR_materials_volume) {
+                exts.PushBack(StringRef("KHR_materials_volume"), mAl);
+            }
+
             if (this->mAsset.extensionsUsed.FB_ngon_encoding) {
                 exts.PushBack(StringRef("FB_ngon_encoding"), mAl);
             }

From addd54125133c590bcf1dda68ca78f9952651f33 Mon Sep 17 00:00:00 2001
From: diharaw <shredhead94@gmail.com>
Date: Thu, 30 Sep 2021 08:47:53 +0100
Subject: [PATCH 3/7] Added gltf2 KHR_materials_ior support.

---
 code/AssetLib/glTF2/glTF2Asset.h         | 12 ++++++++++
 code/AssetLib/glTF2/glTF2Asset.inl       | 16 ++++++++++++++
 code/AssetLib/glTF2/glTF2AssetWriter.h   |  1 +
 code/AssetLib/glTF2/glTF2AssetWriter.inl | 18 +++++++++++++++
 code/AssetLib/glTF2/glTF2Exporter.cpp    | 28 ++++++++++++++++++++++++
 code/AssetLib/glTF2/glTF2Exporter.h      |  4 ++++
 code/AssetLib/glTF2/glTF2Importer.cpp    |  7 ++++++
 include/assimp/material.h                | 12 ++++++++--
 8 files changed, 96 insertions(+), 2 deletions(-)

diff --git a/code/AssetLib/glTF2/glTF2Asset.h b/code/AssetLib/glTF2/glTF2Asset.h
index fb3100b2c..c790a1374 100644
--- a/code/AssetLib/glTF2/glTF2Asset.h
+++ b/code/AssetLib/glTF2/glTF2Asset.h
@@ -50,6 +50,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *   KHR_materials_clearcoat full
  *   KHR_materials_transmission full
  *   KHR_materials_volume full
+ *   KHR_materials_ior full
  */
 #ifndef GLTF2ASSET_H_INC
 #define GLTF2ASSET_H_INC
@@ -789,6 +790,13 @@ struct MaterialVolume {
     void SetDefaults();
 };
 
+struct MaterialIOR {
+    float ior = 0.f;
+
+    MaterialIOR() { SetDefaults(); }
+    void SetDefaults();
+};
+
 //! The material appearance of a primitive.
 struct Material : public Object {
     //PBR metallic roughness properties
@@ -817,6 +825,9 @@ struct Material : public Object {
 
     //extension: KHR_materials_volume
     Nullable<MaterialVolume> materialVolume;
+
+    //extension: KHR_materials_ior
+    Nullable<MaterialIOR> materialIOR;
     
     //extension: KHR_materials_unlit
     bool unlit;
@@ -1107,6 +1118,7 @@ public:
         bool KHR_materials_clearcoat;
         bool KHR_materials_transmission;
         bool KHR_materials_volume;
+        bool KHR_materials_ior;
         bool KHR_draco_mesh_compression;
         bool FB_ngon_encoding;
         bool KHR_texture_basisu;
diff --git a/code/AssetLib/glTF2/glTF2Asset.inl b/code/AssetLib/glTF2/glTF2Asset.inl
index ff71ff53b..d65b4132b 100644
--- a/code/AssetLib/glTF2/glTF2Asset.inl
+++ b/code/AssetLib/glTF2/glTF2Asset.inl
@@ -1228,6 +1228,16 @@ inline void Material::Read(Value &material, Asset &r) {
             }
         }
 
+        if (r.extensionsUsed.KHR_materials_ior) {
+            if (Value *curMaterialIOR = FindObject(*extensions, "KHR_materials_ior")) {
+                MaterialIOR ior;
+
+                ReadMember(*curMaterialIOR, "ior", ior.ior);
+          
+                this->materialIOR = Nullable<MaterialIOR>(ior);
+            }
+        }
+
         unlit = nullptr != FindObject(*extensions, "KHR_materials_unlit");
     }
 }
@@ -1280,6 +1290,11 @@ inline void MaterialVolume::SetDefaults() {
     SetVector(attenuationColor, defaultAttenuationColor);
 }
 
+inline void MaterialIOR::SetDefaults() {
+    //KHR_materials_ior properties
+    ior = 1.5f;
+}
+
 namespace {
 
 template <int N>
@@ -1952,6 +1967,7 @@ inline void Asset::ReadExtensionsUsed(Document &doc) {
     CHECK_EXT(KHR_materials_clearcoat);
     CHECK_EXT(KHR_materials_transmission);
     CHECK_EXT(KHR_materials_volume);
+    CHECK_EXT(KHR_materials_ior);
     CHECK_EXT(KHR_draco_mesh_compression);
     CHECK_EXT(KHR_texture_basisu);
 
diff --git a/code/AssetLib/glTF2/glTF2AssetWriter.h b/code/AssetLib/glTF2/glTF2AssetWriter.h
index 9be3fdf0c..ce8b4d65e 100644
--- a/code/AssetLib/glTF2/glTF2AssetWriter.h
+++ b/code/AssetLib/glTF2/glTF2AssetWriter.h
@@ -50,6 +50,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *   KHR_materials_clearcoat: full
  *   KHR_materials_transmission: full
  *   KHR_materials_volume: full
+ *   KHR_materials_ior: full
  */
 #ifndef GLTF2ASSETWRITER_H_INC
 #define GLTF2ASSETWRITER_H_INC
diff --git a/code/AssetLib/glTF2/glTF2AssetWriter.inl b/code/AssetLib/glTF2/glTF2AssetWriter.inl
index 03b8476dc..b91553fbe 100644
--- a/code/AssetLib/glTF2/glTF2AssetWriter.inl
+++ b/code/AssetLib/glTF2/glTF2AssetWriter.inl
@@ -496,6 +496,20 @@ namespace glTF2 {
             }
         }
 
+        if (m.materialIOR.isPresent) {
+            Value materialIOR(rapidjson::Type::kObjectType);
+
+            MaterialIOR &ior = m.materialIOR.value;
+
+            if (ior.ior != 1.5f) {
+                WriteFloat(materialIOR, ior.ior, "ior", w.mAl);
+            }
+
+            if (!materialIOR.ObjectEmpty()) {
+                exts.AddMember("KHR_materials_ior", materialIOR, w.mAl);
+            }
+        }
+
         if (!exts.ObjectEmpty()) {
             obj.AddMember("extensions", exts, w.mAl);
         }
@@ -916,6 +930,10 @@ namespace glTF2 {
                 exts.PushBack(StringRef("KHR_materials_volume"), mAl);
             }
 
+            if (this->mAsset.extensionsUsed.KHR_materials_ior) {
+                exts.PushBack(StringRef("KHR_materials_ior"), mAl);
+            }
+
             if (this->mAsset.extensionsUsed.FB_ngon_encoding) {
                 exts.PushBack(StringRef("FB_ngon_encoding"), mAl);
             }
diff --git a/code/AssetLib/glTF2/glTF2Exporter.cpp b/code/AssetLib/glTF2/glTF2Exporter.cpp
index 22db4b26d..8327f8c54 100644
--- a/code/AssetLib/glTF2/glTF2Exporter.cpp
+++ b/code/AssetLib/glTF2/glTF2Exporter.cpp
@@ -704,6 +704,22 @@ bool glTF2Exporter::GetMatTransmission(const aiMaterial &mat, glTF2::MaterialTra
     return result || transmission.transmissionTexture.texture;
 }
 
+bool glTF2Exporter::GetMatVolume(const aiMaterial &mat, glTF2::MaterialVolume &volume) {
+    bool result = mat.Get(AI_MATKEY_VOLUME_THICKNESS_FACTOR, volume.thicknessFactor) != aiReturn_SUCCESS;
+
+    GetMatTex(mat, volume.thicknessTexture, AI_MATKEY_VOLUME_THICKNESS_TEXTURE);
+
+    result = result || mat.Get(AI_MATKEY_VOLUME_ATTENUATION_DISTANCE, volume.attenuationDistance);
+    result = result || GetMatColor(mat, volume.attenuationColor, AI_MATKEY_VOLUME_ATTENUATION_COLOR) != aiReturn_SUCCESS;
+
+    // Valid if any of these properties are available
+    return result || volume.thicknessTexture.texture;
+}
+
+bool glTF2Exporter::GetMatIOR(const aiMaterial &mat, glTF2::MaterialIOR &ior) {
+    return mat.Get(AI_MATKEY_IOR, ior.ior) == aiReturn_SUCCESS;
+}
+
 void glTF2Exporter::ExportMaterials() {
     aiString aiName;
     for (unsigned int i = 0; i < mScene->mNumMaterials; ++i) {
@@ -824,6 +840,18 @@ void glTF2Exporter::ExportMaterials() {
                     mAsset->extensionsUsed.KHR_materials_transmission = true;
                     m->materialTransmission = Nullable<MaterialTransmission>(transmission);
                 }
+                
+                MaterialVolume volume;
+                if (GetMatVolume(mat, volume)) {
+                    mAsset->extensionsUsed.KHR_materials_volume = true;
+                    m->materialVolume = Nullable<MaterialVolume>(volume);
+                }
+                                
+                MaterialIOR ior;
+                if (GetMatIOR(mat, ior)) {
+                    mAsset->extensionsUsed.KHR_materials_ior = true;
+                    m->materialIOR = Nullable<MaterialIOR>(ior);
+                }
             }
         }
     }
diff --git a/code/AssetLib/glTF2/glTF2Exporter.h b/code/AssetLib/glTF2/glTF2Exporter.h
index 842d29815..6d70d915e 100644
--- a/code/AssetLib/glTF2/glTF2Exporter.h
+++ b/code/AssetLib/glTF2/glTF2Exporter.h
@@ -77,6 +77,8 @@ struct PbrSpecularGlossiness;
 struct MaterialSheen;
 struct MaterialClearcoat;
 struct MaterialTransmission;
+struct MaterialVolume;
+struct MaterialIOR;
 
 // Vec/matrix types, as raw float arrays
 typedef float(vec2)[2];
@@ -114,6 +116,8 @@ protected:
     bool GetMatSheen(const aiMaterial &mat, glTF2::MaterialSheen &sheen);
     bool GetMatClearcoat(const aiMaterial &mat, glTF2::MaterialClearcoat &clearcoat);
     bool GetMatTransmission(const aiMaterial &mat, glTF2::MaterialTransmission &transmission);
+    bool GetMatVolume(const aiMaterial &mat, glTF2::MaterialVolume &volume);
+    bool GetMatIOR(const aiMaterial &mat, glTF2::MaterialIOR &ior);
     void ExportMetadata();
     void ExportMaterials();
     void ExportMeshes();
diff --git a/code/AssetLib/glTF2/glTF2Importer.cpp b/code/AssetLib/glTF2/glTF2Importer.cpp
index 136b01d07..c7de2af4f 100644
--- a/code/AssetLib/glTF2/glTF2Importer.cpp
+++ b/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -351,6 +351,13 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
             SetMaterialColorProperty(r, volume.attenuationColor, aimat, AI_MATKEY_VOLUME_ATTENUATION_COLOR);
         }
 
+        // KHR_materials_ior
+        if (mat.materialIOR.isPresent) {
+            MaterialIOR &ior = mat.materialIOR.value;
+
+            aimat->AddProperty(&ior.ior, 1, AI_MATKEY_IOR);
+        }
+
         return aimat;
     } catch (...) {
         delete aimat;
diff --git a/include/assimp/material.h b/include/assimp/material.h
index 2373185fc..c86848993 100644
--- a/include/assimp/material.h
+++ b/include/assimp/material.h
@@ -1037,14 +1037,22 @@ extern "C" {
 // Volume
 // ------------
 // https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_volume
-// Base percentage of light transmitted through the surface. 0.0 = Opaque, 1.0 = Fully transparent
+// The thickness of the volume beneath the surface. If the value is 0 the material is thin-walled. Otherwise the material is a volume boundary.
 #define AI_MATKEY_VOLUME_THICKNESS_FACTOR "$mat.volume.thicknessFactor", 0, 0
-// Texture defining percentage of light transmitted through the surface.
+// Texture that defines the thickness.
 // Multiplied by AI_MATKEY_THICKNESS_FACTOR
 #define AI_MATKEY_VOLUME_THICKNESS_TEXTURE aiTextureType_VOLUME, 0
+// Density of the medium given as the average distance that light travels in the medium before interacting with a particle.
 #define AI_MATKEY_VOLUME_ATTENUATION_DISTANCE "$mat.volume.attenuationDistance", 0, 0
+// The color that white light turns into due to absorption when reaching the attenuation distance.
 #define AI_MATKEY_VOLUME_ATTENUATION_COLOR "$mat.volume.attenuationColor", 0, 0
 
+// IOR
+// ------------
+// https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_ior
+// Index of Refraction.
+#define AI_MATKEY_IOR "$mat.ior", 0, 0
+
 // Emissive
 // --------
 #define AI_MATKEY_USE_EMISSIVE_MAP "$mat.useEmissiveMap", 0, 0

From 46a7de7a0b21ebf03c8128fb3952db4c4d670228 Mon Sep 17 00:00:00 2001
From: diharaw <shredhead94@gmail.com>
Date: Thu, 30 Sep 2021 08:56:16 +0100
Subject: [PATCH 4/7] Moved KHR_material_volume thickness texture under
 aiTextureType_TRANSMISSION.

---
 include/assimp/material.h | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/include/assimp/material.h b/include/assimp/material.h
index c86848993..5499bd916 100644
--- a/include/assimp/material.h
+++ b/include/assimp/material.h
@@ -318,12 +318,6 @@ enum aiTextureType {
     */
     aiTextureType_TRANSMISSION = 21,
 
-    /** Volume
-    * Simulates transmission through the surface
-    * May include further information such as wall thickness
-    */
-    aiTextureType_VOLUME = 22,
-
     /** Unknown texture
      *
      *  A texture reference that does not match any of the definitions
@@ -1041,7 +1035,7 @@ extern "C" {
 #define AI_MATKEY_VOLUME_THICKNESS_FACTOR "$mat.volume.thicknessFactor", 0, 0
 // Texture that defines the thickness.
 // Multiplied by AI_MATKEY_THICKNESS_FACTOR
-#define AI_MATKEY_VOLUME_THICKNESS_TEXTURE aiTextureType_VOLUME, 0
+#define AI_MATKEY_VOLUME_THICKNESS_TEXTURE aiTextureType_TRANSMISSION, 1
 // Density of the medium given as the average distance that light travels in the medium before interacting with a particle.
 #define AI_MATKEY_VOLUME_ATTENUATION_DISTANCE "$mat.volume.attenuationDistance", 0, 0
 // The color that white light turns into due to absorption when reaching the attenuation distance.

From 0738742611dba94d9adef998e59df963ba8c4115 Mon Sep 17 00:00:00 2001
From: diharaw <shredhead94@gmail.com>
Date: Thu, 7 Oct 2021 09:30:22 +0100
Subject: [PATCH 5/7] Removed KHR_materials_ior support.

---
 code/AssetLib/glTF2/glTF2Asset.h         | 12 ------------
 code/AssetLib/glTF2/glTF2Asset.inl       | 16 ----------------
 code/AssetLib/glTF2/glTF2AssetWriter.h   |  1 -
 code/AssetLib/glTF2/glTF2AssetWriter.inl | 18 ------------------
 code/AssetLib/glTF2/glTF2Exporter.cpp    | 10 ----------
 code/AssetLib/glTF2/glTF2Exporter.h      |  2 --
 code/AssetLib/glTF2/glTF2Importer.cpp    |  7 -------
 include/assimp/material.h                |  6 ------
 8 files changed, 72 deletions(-)

diff --git a/code/AssetLib/glTF2/glTF2Asset.h b/code/AssetLib/glTF2/glTF2Asset.h
index c790a1374..e97523bbe 100644
--- a/code/AssetLib/glTF2/glTF2Asset.h
+++ b/code/AssetLib/glTF2/glTF2Asset.h
@@ -50,7 +50,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *   KHR_materials_clearcoat full
  *   KHR_materials_transmission full
  *   KHR_materials_volume full
- *   KHR_materials_ior full
  */
 #ifndef GLTF2ASSET_H_INC
 #define GLTF2ASSET_H_INC
@@ -790,13 +789,6 @@ struct MaterialVolume {
     void SetDefaults();
 };
 
-struct MaterialIOR {
-    float ior = 0.f;
-
-    MaterialIOR() { SetDefaults(); }
-    void SetDefaults();
-};
-
 //! The material appearance of a primitive.
 struct Material : public Object {
     //PBR metallic roughness properties
@@ -826,9 +818,6 @@ struct Material : public Object {
     //extension: KHR_materials_volume
     Nullable<MaterialVolume> materialVolume;
 
-    //extension: KHR_materials_ior
-    Nullable<MaterialIOR> materialIOR;
-    
     //extension: KHR_materials_unlit
     bool unlit;
 
@@ -1118,7 +1107,6 @@ public:
         bool KHR_materials_clearcoat;
         bool KHR_materials_transmission;
         bool KHR_materials_volume;
-        bool KHR_materials_ior;
         bool KHR_draco_mesh_compression;
         bool FB_ngon_encoding;
         bool KHR_texture_basisu;
diff --git a/code/AssetLib/glTF2/glTF2Asset.inl b/code/AssetLib/glTF2/glTF2Asset.inl
index d65b4132b..ff71ff53b 100644
--- a/code/AssetLib/glTF2/glTF2Asset.inl
+++ b/code/AssetLib/glTF2/glTF2Asset.inl
@@ -1228,16 +1228,6 @@ inline void Material::Read(Value &material, Asset &r) {
             }
         }
 
-        if (r.extensionsUsed.KHR_materials_ior) {
-            if (Value *curMaterialIOR = FindObject(*extensions, "KHR_materials_ior")) {
-                MaterialIOR ior;
-
-                ReadMember(*curMaterialIOR, "ior", ior.ior);
-          
-                this->materialIOR = Nullable<MaterialIOR>(ior);
-            }
-        }
-
         unlit = nullptr != FindObject(*extensions, "KHR_materials_unlit");
     }
 }
@@ -1290,11 +1280,6 @@ inline void MaterialVolume::SetDefaults() {
     SetVector(attenuationColor, defaultAttenuationColor);
 }
 
-inline void MaterialIOR::SetDefaults() {
-    //KHR_materials_ior properties
-    ior = 1.5f;
-}
-
 namespace {
 
 template <int N>
@@ -1967,7 +1952,6 @@ inline void Asset::ReadExtensionsUsed(Document &doc) {
     CHECK_EXT(KHR_materials_clearcoat);
     CHECK_EXT(KHR_materials_transmission);
     CHECK_EXT(KHR_materials_volume);
-    CHECK_EXT(KHR_materials_ior);
     CHECK_EXT(KHR_draco_mesh_compression);
     CHECK_EXT(KHR_texture_basisu);
 
diff --git a/code/AssetLib/glTF2/glTF2AssetWriter.h b/code/AssetLib/glTF2/glTF2AssetWriter.h
index ce8b4d65e..9be3fdf0c 100644
--- a/code/AssetLib/glTF2/glTF2AssetWriter.h
+++ b/code/AssetLib/glTF2/glTF2AssetWriter.h
@@ -50,7 +50,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *   KHR_materials_clearcoat: full
  *   KHR_materials_transmission: full
  *   KHR_materials_volume: full
- *   KHR_materials_ior: full
  */
 #ifndef GLTF2ASSETWRITER_H_INC
 #define GLTF2ASSETWRITER_H_INC
diff --git a/code/AssetLib/glTF2/glTF2AssetWriter.inl b/code/AssetLib/glTF2/glTF2AssetWriter.inl
index b91553fbe..03b8476dc 100644
--- a/code/AssetLib/glTF2/glTF2AssetWriter.inl
+++ b/code/AssetLib/glTF2/glTF2AssetWriter.inl
@@ -496,20 +496,6 @@ namespace glTF2 {
             }
         }
 
-        if (m.materialIOR.isPresent) {
-            Value materialIOR(rapidjson::Type::kObjectType);
-
-            MaterialIOR &ior = m.materialIOR.value;
-
-            if (ior.ior != 1.5f) {
-                WriteFloat(materialIOR, ior.ior, "ior", w.mAl);
-            }
-
-            if (!materialIOR.ObjectEmpty()) {
-                exts.AddMember("KHR_materials_ior", materialIOR, w.mAl);
-            }
-        }
-
         if (!exts.ObjectEmpty()) {
             obj.AddMember("extensions", exts, w.mAl);
         }
@@ -930,10 +916,6 @@ namespace glTF2 {
                 exts.PushBack(StringRef("KHR_materials_volume"), mAl);
             }
 
-            if (this->mAsset.extensionsUsed.KHR_materials_ior) {
-                exts.PushBack(StringRef("KHR_materials_ior"), mAl);
-            }
-
             if (this->mAsset.extensionsUsed.FB_ngon_encoding) {
                 exts.PushBack(StringRef("FB_ngon_encoding"), mAl);
             }
diff --git a/code/AssetLib/glTF2/glTF2Exporter.cpp b/code/AssetLib/glTF2/glTF2Exporter.cpp
index 8327f8c54..46433fc95 100644
--- a/code/AssetLib/glTF2/glTF2Exporter.cpp
+++ b/code/AssetLib/glTF2/glTF2Exporter.cpp
@@ -716,10 +716,6 @@ bool glTF2Exporter::GetMatVolume(const aiMaterial &mat, glTF2::MaterialVolume &v
     return result || volume.thicknessTexture.texture;
 }
 
-bool glTF2Exporter::GetMatIOR(const aiMaterial &mat, glTF2::MaterialIOR &ior) {
-    return mat.Get(AI_MATKEY_IOR, ior.ior) == aiReturn_SUCCESS;
-}
-
 void glTF2Exporter::ExportMaterials() {
     aiString aiName;
     for (unsigned int i = 0; i < mScene->mNumMaterials; ++i) {
@@ -846,12 +842,6 @@ void glTF2Exporter::ExportMaterials() {
                     mAsset->extensionsUsed.KHR_materials_volume = true;
                     m->materialVolume = Nullable<MaterialVolume>(volume);
                 }
-                                
-                MaterialIOR ior;
-                if (GetMatIOR(mat, ior)) {
-                    mAsset->extensionsUsed.KHR_materials_ior = true;
-                    m->materialIOR = Nullable<MaterialIOR>(ior);
-                }
             }
         }
     }
diff --git a/code/AssetLib/glTF2/glTF2Exporter.h b/code/AssetLib/glTF2/glTF2Exporter.h
index 6d70d915e..c00faafb9 100644
--- a/code/AssetLib/glTF2/glTF2Exporter.h
+++ b/code/AssetLib/glTF2/glTF2Exporter.h
@@ -78,7 +78,6 @@ struct MaterialSheen;
 struct MaterialClearcoat;
 struct MaterialTransmission;
 struct MaterialVolume;
-struct MaterialIOR;
 
 // Vec/matrix types, as raw float arrays
 typedef float(vec2)[2];
@@ -117,7 +116,6 @@ protected:
     bool GetMatClearcoat(const aiMaterial &mat, glTF2::MaterialClearcoat &clearcoat);
     bool GetMatTransmission(const aiMaterial &mat, glTF2::MaterialTransmission &transmission);
     bool GetMatVolume(const aiMaterial &mat, glTF2::MaterialVolume &volume);
-    bool GetMatIOR(const aiMaterial &mat, glTF2::MaterialIOR &ior);
     void ExportMetadata();
     void ExportMaterials();
     void ExportMeshes();
diff --git a/code/AssetLib/glTF2/glTF2Importer.cpp b/code/AssetLib/glTF2/glTF2Importer.cpp
index c7de2af4f..136b01d07 100644
--- a/code/AssetLib/glTF2/glTF2Importer.cpp
+++ b/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -351,13 +351,6 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
             SetMaterialColorProperty(r, volume.attenuationColor, aimat, AI_MATKEY_VOLUME_ATTENUATION_COLOR);
         }
 
-        // KHR_materials_ior
-        if (mat.materialIOR.isPresent) {
-            MaterialIOR &ior = mat.materialIOR.value;
-
-            aimat->AddProperty(&ior.ior, 1, AI_MATKEY_IOR);
-        }
-
         return aimat;
     } catch (...) {
         delete aimat;
diff --git a/include/assimp/material.h b/include/assimp/material.h
index 5499bd916..4e55e4894 100644
--- a/include/assimp/material.h
+++ b/include/assimp/material.h
@@ -1041,12 +1041,6 @@ extern "C" {
 // The color that white light turns into due to absorption when reaching the attenuation distance.
 #define AI_MATKEY_VOLUME_ATTENUATION_COLOR "$mat.volume.attenuationColor", 0, 0
 
-// IOR
-// ------------
-// https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_ior
-// Index of Refraction.
-#define AI_MATKEY_IOR "$mat.ior", 0, 0
-
 // Emissive
 // --------
 #define AI_MATKEY_USE_EMISSIVE_MAP "$mat.useEmissiveMap", 0, 0

From b01d008bc0d8042bd2395be4b0a8b0bb2eaaa0c6 Mon Sep 17 00:00:00 2001
From: diharaw <shredhead94@gmail.com>
Date: Thu, 7 Oct 2021 09:36:53 +0100
Subject: [PATCH 6/7] Revert "Removed KHR_materials_ior support."

This reverts commit 0738742611dba94d9adef998e59df963ba8c4115.
---
 code/AssetLib/glTF2/glTF2Asset.h         | 12 ++++++++++++
 code/AssetLib/glTF2/glTF2Asset.inl       | 16 ++++++++++++++++
 code/AssetLib/glTF2/glTF2AssetWriter.h   |  1 +
 code/AssetLib/glTF2/glTF2AssetWriter.inl | 18 ++++++++++++++++++
 code/AssetLib/glTF2/glTF2Exporter.cpp    | 10 ++++++++++
 code/AssetLib/glTF2/glTF2Exporter.h      |  2 ++
 code/AssetLib/glTF2/glTF2Importer.cpp    |  7 +++++++
 include/assimp/material.h                |  6 ++++++
 8 files changed, 72 insertions(+)

diff --git a/code/AssetLib/glTF2/glTF2Asset.h b/code/AssetLib/glTF2/glTF2Asset.h
index e97523bbe..c790a1374 100644
--- a/code/AssetLib/glTF2/glTF2Asset.h
+++ b/code/AssetLib/glTF2/glTF2Asset.h
@@ -50,6 +50,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *   KHR_materials_clearcoat full
  *   KHR_materials_transmission full
  *   KHR_materials_volume full
+ *   KHR_materials_ior full
  */
 #ifndef GLTF2ASSET_H_INC
 #define GLTF2ASSET_H_INC
@@ -789,6 +790,13 @@ struct MaterialVolume {
     void SetDefaults();
 };
 
+struct MaterialIOR {
+    float ior = 0.f;
+
+    MaterialIOR() { SetDefaults(); }
+    void SetDefaults();
+};
+
 //! The material appearance of a primitive.
 struct Material : public Object {
     //PBR metallic roughness properties
@@ -818,6 +826,9 @@ struct Material : public Object {
     //extension: KHR_materials_volume
     Nullable<MaterialVolume> materialVolume;
 
+    //extension: KHR_materials_ior
+    Nullable<MaterialIOR> materialIOR;
+    
     //extension: KHR_materials_unlit
     bool unlit;
 
@@ -1107,6 +1118,7 @@ public:
         bool KHR_materials_clearcoat;
         bool KHR_materials_transmission;
         bool KHR_materials_volume;
+        bool KHR_materials_ior;
         bool KHR_draco_mesh_compression;
         bool FB_ngon_encoding;
         bool KHR_texture_basisu;
diff --git a/code/AssetLib/glTF2/glTF2Asset.inl b/code/AssetLib/glTF2/glTF2Asset.inl
index ff71ff53b..d65b4132b 100644
--- a/code/AssetLib/glTF2/glTF2Asset.inl
+++ b/code/AssetLib/glTF2/glTF2Asset.inl
@@ -1228,6 +1228,16 @@ inline void Material::Read(Value &material, Asset &r) {
             }
         }
 
+        if (r.extensionsUsed.KHR_materials_ior) {
+            if (Value *curMaterialIOR = FindObject(*extensions, "KHR_materials_ior")) {
+                MaterialIOR ior;
+
+                ReadMember(*curMaterialIOR, "ior", ior.ior);
+          
+                this->materialIOR = Nullable<MaterialIOR>(ior);
+            }
+        }
+
         unlit = nullptr != FindObject(*extensions, "KHR_materials_unlit");
     }
 }
@@ -1280,6 +1290,11 @@ inline void MaterialVolume::SetDefaults() {
     SetVector(attenuationColor, defaultAttenuationColor);
 }
 
+inline void MaterialIOR::SetDefaults() {
+    //KHR_materials_ior properties
+    ior = 1.5f;
+}
+
 namespace {
 
 template <int N>
@@ -1952,6 +1967,7 @@ inline void Asset::ReadExtensionsUsed(Document &doc) {
     CHECK_EXT(KHR_materials_clearcoat);
     CHECK_EXT(KHR_materials_transmission);
     CHECK_EXT(KHR_materials_volume);
+    CHECK_EXT(KHR_materials_ior);
     CHECK_EXT(KHR_draco_mesh_compression);
     CHECK_EXT(KHR_texture_basisu);
 
diff --git a/code/AssetLib/glTF2/glTF2AssetWriter.h b/code/AssetLib/glTF2/glTF2AssetWriter.h
index 9be3fdf0c..ce8b4d65e 100644
--- a/code/AssetLib/glTF2/glTF2AssetWriter.h
+++ b/code/AssetLib/glTF2/glTF2AssetWriter.h
@@ -50,6 +50,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *   KHR_materials_clearcoat: full
  *   KHR_materials_transmission: full
  *   KHR_materials_volume: full
+ *   KHR_materials_ior: full
  */
 #ifndef GLTF2ASSETWRITER_H_INC
 #define GLTF2ASSETWRITER_H_INC
diff --git a/code/AssetLib/glTF2/glTF2AssetWriter.inl b/code/AssetLib/glTF2/glTF2AssetWriter.inl
index 03b8476dc..b91553fbe 100644
--- a/code/AssetLib/glTF2/glTF2AssetWriter.inl
+++ b/code/AssetLib/glTF2/glTF2AssetWriter.inl
@@ -496,6 +496,20 @@ namespace glTF2 {
             }
         }
 
+        if (m.materialIOR.isPresent) {
+            Value materialIOR(rapidjson::Type::kObjectType);
+
+            MaterialIOR &ior = m.materialIOR.value;
+
+            if (ior.ior != 1.5f) {
+                WriteFloat(materialIOR, ior.ior, "ior", w.mAl);
+            }
+
+            if (!materialIOR.ObjectEmpty()) {
+                exts.AddMember("KHR_materials_ior", materialIOR, w.mAl);
+            }
+        }
+
         if (!exts.ObjectEmpty()) {
             obj.AddMember("extensions", exts, w.mAl);
         }
@@ -916,6 +930,10 @@ namespace glTF2 {
                 exts.PushBack(StringRef("KHR_materials_volume"), mAl);
             }
 
+            if (this->mAsset.extensionsUsed.KHR_materials_ior) {
+                exts.PushBack(StringRef("KHR_materials_ior"), mAl);
+            }
+
             if (this->mAsset.extensionsUsed.FB_ngon_encoding) {
                 exts.PushBack(StringRef("FB_ngon_encoding"), mAl);
             }
diff --git a/code/AssetLib/glTF2/glTF2Exporter.cpp b/code/AssetLib/glTF2/glTF2Exporter.cpp
index 46433fc95..8327f8c54 100644
--- a/code/AssetLib/glTF2/glTF2Exporter.cpp
+++ b/code/AssetLib/glTF2/glTF2Exporter.cpp
@@ -716,6 +716,10 @@ bool glTF2Exporter::GetMatVolume(const aiMaterial &mat, glTF2::MaterialVolume &v
     return result || volume.thicknessTexture.texture;
 }
 
+bool glTF2Exporter::GetMatIOR(const aiMaterial &mat, glTF2::MaterialIOR &ior) {
+    return mat.Get(AI_MATKEY_IOR, ior.ior) == aiReturn_SUCCESS;
+}
+
 void glTF2Exporter::ExportMaterials() {
     aiString aiName;
     for (unsigned int i = 0; i < mScene->mNumMaterials; ++i) {
@@ -842,6 +846,12 @@ void glTF2Exporter::ExportMaterials() {
                     mAsset->extensionsUsed.KHR_materials_volume = true;
                     m->materialVolume = Nullable<MaterialVolume>(volume);
                 }
+                                
+                MaterialIOR ior;
+                if (GetMatIOR(mat, ior)) {
+                    mAsset->extensionsUsed.KHR_materials_ior = true;
+                    m->materialIOR = Nullable<MaterialIOR>(ior);
+                }
             }
         }
     }
diff --git a/code/AssetLib/glTF2/glTF2Exporter.h b/code/AssetLib/glTF2/glTF2Exporter.h
index c00faafb9..6d70d915e 100644
--- a/code/AssetLib/glTF2/glTF2Exporter.h
+++ b/code/AssetLib/glTF2/glTF2Exporter.h
@@ -78,6 +78,7 @@ struct MaterialSheen;
 struct MaterialClearcoat;
 struct MaterialTransmission;
 struct MaterialVolume;
+struct MaterialIOR;
 
 // Vec/matrix types, as raw float arrays
 typedef float(vec2)[2];
@@ -116,6 +117,7 @@ protected:
     bool GetMatClearcoat(const aiMaterial &mat, glTF2::MaterialClearcoat &clearcoat);
     bool GetMatTransmission(const aiMaterial &mat, glTF2::MaterialTransmission &transmission);
     bool GetMatVolume(const aiMaterial &mat, glTF2::MaterialVolume &volume);
+    bool GetMatIOR(const aiMaterial &mat, glTF2::MaterialIOR &ior);
     void ExportMetadata();
     void ExportMaterials();
     void ExportMeshes();
diff --git a/code/AssetLib/glTF2/glTF2Importer.cpp b/code/AssetLib/glTF2/glTF2Importer.cpp
index 136b01d07..c7de2af4f 100644
--- a/code/AssetLib/glTF2/glTF2Importer.cpp
+++ b/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -351,6 +351,13 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
             SetMaterialColorProperty(r, volume.attenuationColor, aimat, AI_MATKEY_VOLUME_ATTENUATION_COLOR);
         }
 
+        // KHR_materials_ior
+        if (mat.materialIOR.isPresent) {
+            MaterialIOR &ior = mat.materialIOR.value;
+
+            aimat->AddProperty(&ior.ior, 1, AI_MATKEY_IOR);
+        }
+
         return aimat;
     } catch (...) {
         delete aimat;
diff --git a/include/assimp/material.h b/include/assimp/material.h
index 4e55e4894..5499bd916 100644
--- a/include/assimp/material.h
+++ b/include/assimp/material.h
@@ -1041,6 +1041,12 @@ extern "C" {
 // The color that white light turns into due to absorption when reaching the attenuation distance.
 #define AI_MATKEY_VOLUME_ATTENUATION_COLOR "$mat.volume.attenuationColor", 0, 0
 
+// IOR
+// ------------
+// https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_ior
+// Index of Refraction.
+#define AI_MATKEY_IOR "$mat.ior", 0, 0
+
 // Emissive
 // --------
 #define AI_MATKEY_USE_EMISSIVE_MAP "$mat.useEmissiveMap", 0, 0

From 0fb66f84378ef441977fd552b6cda2ff3dd7216d Mon Sep 17 00:00:00 2001
From: diharaw <shredhead94@gmail.com>
Date: Thu, 7 Oct 2021 09:39:08 +0100
Subject: [PATCH 7/7] Replaced AI_MATKEY_IOR with AI_MATKEY_REFRACTI.

---
 code/AssetLib/glTF2/glTF2Exporter.cpp | 2 +-
 code/AssetLib/glTF2/glTF2Importer.cpp | 2 +-
 include/assimp/material.h             | 6 ------
 3 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/code/AssetLib/glTF2/glTF2Exporter.cpp b/code/AssetLib/glTF2/glTF2Exporter.cpp
index 8327f8c54..572c61f2b 100644
--- a/code/AssetLib/glTF2/glTF2Exporter.cpp
+++ b/code/AssetLib/glTF2/glTF2Exporter.cpp
@@ -717,7 +717,7 @@ bool glTF2Exporter::GetMatVolume(const aiMaterial &mat, glTF2::MaterialVolume &v
 }
 
 bool glTF2Exporter::GetMatIOR(const aiMaterial &mat, glTF2::MaterialIOR &ior) {
-    return mat.Get(AI_MATKEY_IOR, ior.ior) == aiReturn_SUCCESS;
+    return mat.Get(AI_MATKEY_REFRACTI, ior.ior) == aiReturn_SUCCESS;
 }
 
 void glTF2Exporter::ExportMaterials() {
diff --git a/code/AssetLib/glTF2/glTF2Importer.cpp b/code/AssetLib/glTF2/glTF2Importer.cpp
index c7de2af4f..87f2604ca 100644
--- a/code/AssetLib/glTF2/glTF2Importer.cpp
+++ b/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -355,7 +355,7 @@ static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, M
         if (mat.materialIOR.isPresent) {
             MaterialIOR &ior = mat.materialIOR.value;
 
-            aimat->AddProperty(&ior.ior, 1, AI_MATKEY_IOR);
+            aimat->AddProperty(&ior.ior, 1, AI_MATKEY_REFRACTI);
         }
 
         return aimat;
diff --git a/include/assimp/material.h b/include/assimp/material.h
index 5499bd916..4e55e4894 100644
--- a/include/assimp/material.h
+++ b/include/assimp/material.h
@@ -1041,12 +1041,6 @@ extern "C" {
 // The color that white light turns into due to absorption when reaching the attenuation distance.
 #define AI_MATKEY_VOLUME_ATTENUATION_COLOR "$mat.volume.attenuationColor", 0, 0
 
-// IOR
-// ------------
-// https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_ior
-// Index of Refraction.
-#define AI_MATKEY_IOR "$mat.ior", 0, 0
-
 // Emissive
 // --------
 #define AI_MATKEY_USE_EMISSIVE_MAP "$mat.useEmissiveMap", 0, 0