Add Deformable material domain

Source/Editor/Surface/Archetypes/Material.cs

@@ -156,6 +156,7 @@ namespace FlaxEditor.Surface.Archetypes
                 case MaterialDomain.Surface:
                 case MaterialDomain.Terrain:
                 case MaterialDomain.Particle:
+                case MaterialDomain.Deformable:
                 {
                     bool isNotUnlit = info.ShadingModel != MaterialShadingModel.Unlit;
                     bool isTransparent = info.BlendMode == MaterialBlendMode.Transparent;

Source/Editor/Viewport/Previews/MaterialPreview.cs

@@ -172,6 +172,9 @@ namespace FlaxEditor.Viewport.Previews
                         usePreviewActor = false;
                         particleMaterial = _material;
                         break;
+                    case MaterialDomain.Deformable:
+                        // TODO: preview Deformable material (eg. by using Spline with Spline Model)
+                        break;
                     default: throw new ArgumentOutOfRangeException();
                     }
                 }