ENH: Option to not use a shading/lighting model

Source/Rendering/Materials/imstkRenderMaterial.h

@@ -56,6 +56,7 @@ public:
     /// surface shading model. Defaults to Phong
     enum class ShadingModel
     {
+        None,    ///< Renders without shading, no lighting
         Phong,   ///< Phong shading model (default)
         Gouraud, ///< Gouraud shading model (default)
         Flat,    ///< Flat shading model with no interpolation

Source/Rendering/VTKRenderer/RenderDelegate/imstkVTKPolyDataRenderDelegate.cpp

@@ -114,6 +114,7 @@ VTKPolyDataRenderDelegate::updateRenderProperties()
         /*actorProperty->UseImageBasedLightingOn();
             actorProperty->SetEnvironmentCubeMap(getVTKTexture(cubemap));*/
 
+        actorProperty->LightingOn();
         actorProperty->SetInterpolationToPBR();
 
         // configure the basic properties
@@ -121,16 +122,23 @@ VTKPolyDataRenderDelegate::updateRenderProperties()
     }
     else if (material->getShadingModel() == RenderMaterial::ShadingModel::Phong)
     {
+        actorProperty->LightingOn();
         actorProperty->SetInterpolationToPhong();
     }
     else if (material->getShadingModel() == RenderMaterial::ShadingModel::Gouraud)
     {
+        actorProperty->LightingOn();
         actorProperty->SetInterpolationToGouraud();
     }
-    else
+    else if (material->getShadingModel() == RenderMaterial::ShadingModel::Flat)
     {
+        actorProperty->LightingOn();
         actorProperty->SetInterpolationToFlat();
     }
+    else if (material->getShadingModel() == RenderMaterial::ShadingModel::None)
+    {
+        actorProperty->LightingOff();
+    }
 
     // Display mode
     switch (material->getDisplayMode())