Fix .obj displacement texture parsing

The string for an opacity texture is a substring of the displacement
texture string. Due to the nature of the string comparison in the
material texture parsing, any displacement textures will be incorrectly
assigned as opacity textures. Fix this by simply performing the check
for displacement texture before checking for opacity texture.

code/ObjFileMtlImporter.cpp

@@ -332,6 +332,11 @@ void ObjFileMtlImporter::getTexture() {
         // Specular texture
         out = & m_pModel->m_pCurrentMaterial->textureSpecular;
         clampIndex = ObjFile::Material::TextureSpecularType;
+    } else if ( !ASSIMP_strincmp( pPtr, DisplacementTexture1.c_str(), static_cast<unsigned int>(DisplacementTexture1.size()) ) ||
+                !ASSIMP_strincmp( pPtr, DisplacementTexture2.c_str(), static_cast<unsigned int>(DisplacementTexture2.size()) ) ) {
+        // Displacement texture
+        out = &m_pModel->m_pCurrentMaterial->textureDisp;
+        clampIndex = ObjFile::Material::TextureDispType;
     } else if ( !ASSIMP_strincmp( pPtr, OpacityTexture.c_str(), static_cast<unsigned int>(OpacityTexture.size()) ) ) {
         // Opacity texture
         out = & m_pModel->m_pCurrentMaterial->textureOpacity;
@@ -354,11 +359,6 @@ void ObjFileMtlImporter::getTexture() {
         // Reflection texture(s)
         //Do nothing here
         return;
-    } else if ( !ASSIMP_strincmp( pPtr, DisplacementTexture1.c_str(), static_cast<unsigned int>(DisplacementTexture1.size()) ) ||
-                !ASSIMP_strincmp( pPtr, DisplacementTexture2.c_str(), static_cast<unsigned int>(DisplacementTexture2.size()) ) ) {
-        // Displacement texture
-        out = &m_pModel->m_pCurrentMaterial->textureDisp;
-        clampIndex = ObjFile::Material::TextureDispType;
     } else if ( !ASSIMP_strincmp( pPtr, SpecularityTexture.c_str(), static_cast<unsigned int>(SpecularityTexture.size()) ) ) {
         // Specularity scaling (glossiness)
         out = & m_pModel->m_pCurrentMaterial->textureSpecularity;