Fix export of metallic and normal texture map. Add support for any shader that can support metallic roughness workflow.

UnityGLTF/Assets/Resources/MetalGlossChannelSwap.shader

@@ -0,0 +1,61 @@
+Shader "Hidden/MetalGlossChannelSwap"
+{
+	Properties
+	{
+		_MainTex ("Texture", 2D) = "white" {}
+	}
+	SubShader
+	{
+		// No culling or depth
+		Cull Off ZWrite Off ZTest Always
+
+		Pass
+		{
+			CGPROGRAM
+			#pragma vertex vert
+			#pragma fragment frag
+
+			#include "UnityCG.cginc"
+
+			struct appdata
+			{
+				float4 vertex : POSITION;
+				float2 uv : TEXCOORD0;
+			};
+
+			struct v2f
+			{
+				float2 uv : TEXCOORD0;
+				float4 vertex : SV_POSITION;
+			};
+
+			v2f vert (appdata v)
+			{
+				v2f o;
+				o.vertex = UnityObjectToClipPos(v.vertex);
+				o.uv = v.uv;
+				return o;
+			}
+
+			sampler2D _MainTex;
+
+			float4 frag (v2f i) : SV_Target
+			{
+				float4 col = tex2D(_MainTex, i.uv);
+				// From the GLTF 2.0 spec
+				// The metallic-roughness texture. The metalness values are sampled from the B channel. 
+				// The roughness values are sampled from the G channel. These values are linear. 
+				// If other channels are present (R or A), they are ignored for metallic-roughness calculations.
+				//
+				// Unity, by default, puts metallic in R channel and glossiness in A channel.
+				// Unity uses a metallic-gloss texture so we need to invert the value in the g channel.
+				//
+				// Conversion Summary
+				// Unity R channel goes into B channel
+				// Unity A channel goes into G channel, then inverted
+				return float4(1, 1 - col.a, col.r, 1);
+			}
+			ENDCG
+		}
+	}
+}

UnityGLTF/Assets/Resources/NormalChannel.shader

@@ -0,0 +1,52 @@
+Shader "Hidden/NormalChannel"
+{
+	Properties
+	{
+		_MainTex ("Texture", 2D) = "white" {}
+	}
+	SubShader
+	{
+		// No culling or depth
+		Cull Off ZWrite Off ZTest Always
+
+		Pass
+		{
+			CGPROGRAM
+			#pragma vertex vert
+			#pragma fragment frag
+
+			#include "UnityCG.cginc"
+
+			struct appdata
+			{
+				float4 vertex : POSITION;
+				float2 uv : TEXCOORD0;
+			};
+
+			struct v2f
+			{
+				float2 uv : TEXCOORD0;
+				float4 vertex : SV_POSITION;
+			};
+
+			v2f vert (appdata v)
+			{
+				v2f o;
+				o.vertex = UnityObjectToClipPos(v.vertex);
+				o.uv = v.uv;
+				return o;
+			}
+
+			sampler2D _MainTex;
+
+			fixed4 frag (v2f i) : SV_Target
+			{
+				float4 col = tex2D(_MainTex, i.uv);
+				// If a texture is marked as a normal map
+				// the values are stored in the A and G channel.
+				return float4(col.a, col.g, 1, 1);
+			}
+			ENDCG
+		}
+	}
+}

UnityGLTF/Assets/UnityGLTF/Scripts/Editor/GLTFExportMenu.cs

@@ -17,8 +17,11 @@ static void ExportSelected()
 			throw new Exception("No objects selected, cannot export.");
 
 		var exporter = new GLTFSceneExporter(Selection.transforms);
+
 		var path = EditorUtility.OpenFolderPanel("glTF Export Path", "", "");
-		exporter.SaveGLTFandBin(path, name);
+		if (!string.IsNullOrEmpty(path)) {
+			exporter.SaveGLTFandBin (path, name);
+		}
 	}
 
 	[MenuItem("GLTF/Export Scene")]
@@ -30,6 +33,8 @@ static void ExportScene()
 
 		var exporter = new GLTFSceneExporter(transforms);
 		var path = EditorUtility.OpenFolderPanel("glTF Export Path", "", "");
-		exporter.SaveGLTFandBin(path, scene.name);
+		if (path != "") {
+			exporter.SaveGLTFandBin (path, scene.name);
+		}
 	}
 }

UnityGLTF/Assets/UnityGLTF/Scripts/Editor/PbrShaderGUI.cs

@@ -56,8 +56,6 @@ private static class Styles
         MaterialProperty bumpMap = null;
         MaterialProperty occlusionStrength = null;
         MaterialProperty occlusionMap = null;
-        MaterialProperty heigtMapScale = null;
-        MaterialProperty heightMap = null;
         MaterialProperty emissionColor = null;
         MaterialProperty emissionMap = null;
 

UnityGLTF/Assets/UnityGLTF/Scripts/GLTFComponent.cs

@@ -10,7 +10,7 @@ namespace UnityGLTF
 	/// </summary>
 	class GLTFComponent : MonoBehaviour
 	{
-		public string Url;
+		public string Url = null;
 		public bool Multithreaded = true;
 		public bool UseStream = false;