From 83c0163ec6935aaf1537fb623488ecb5007a2334 Mon Sep 17 00:00:00 2001
From: John Senneker <johns@matterandform.net>
Date: Thu, 29 Sep 2016 17:44:04 -0400
Subject: [PATCH] glTF: Read and write transparency values

---
 code/glTFAsset.inl       | 1 +
 code/glTFAssetWriter.inl | 3 +++
 code/glTFExporter.cpp    | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/code/glTFAsset.inl b/code/glTFAsset.inl
index b9f3fccd8..64966fb28 100644
--- a/code/glTFAsset.inl
+++ b/code/glTFAsset.inl
@@ -696,6 +696,7 @@ inline void Material::Read(Value& material, Asset& r)
         ReadMaterialProperty(r, *values, "diffuse", this->diffuse);
         ReadMaterialProperty(r, *values, "specular", this->specular);
 
+        ReadMember(*values, "transparency", transparency);
         ReadMember(*values, "shininess", shininess);
     }
 
diff --git a/code/glTFAssetWriter.inl b/code/glTFAssetWriter.inl
index 119ebc937..af27604f2 100644
--- a/code/glTFAssetWriter.inl
+++ b/code/glTFAssetWriter.inl
@@ -171,6 +171,9 @@ namespace glTF {
             WriteColorOrTex(v, m.specular, "specular", w.mAl);
             WriteColorOrTex(v, m.emission, "emission", w.mAl);
 
+            if (m.transparent)
+                v.AddMember("transparency", m.transparency, w.mAl);
+
             v.AddMember("shininess", m.shininess, w.mAl);
         }
         obj.AddMember("values", v, w.mAl);
diff --git a/code/glTFExporter.cpp b/code/glTFExporter.cpp
index 708570577..8f37452b1 100644
--- a/code/glTFExporter.cpp
+++ b/code/glTFExporter.cpp
@@ -274,6 +274,8 @@ void glTFExporter::ExportMaterials()
         GetMatColorOrTex(mat, m->specular, AI_MATKEY_COLOR_SPECULAR, aiTextureType_SPECULAR);
         GetMatColorOrTex(mat, m->emission, AI_MATKEY_COLOR_EMISSIVE, aiTextureType_EMISSIVE);
 
+        m->transparent = mat->Get(AI_MATKEY_OPACITY, m->transparency) == aiReturn_SUCCESS && m->transparency != 1.0;
+
         GetMatScalar(mat, m->shininess, AI_MATKEY_SHININESS);
     }
 }