I am a huge fan of MaterialParamterCollections and use them whenever possible, however there is one that needs to be addressed; MaterialParameterCollection values cannot be previewed live in the material graph, using a CollectionParameter in a node network will end up causing every node’s preview to be totally black that is connected in that network. I have some images here to demonstrate what I mean, they were captured in 4.6.1, but I have confirmed in 4.7 preview 7 occurs as well.
is what you will see using the VectorParameter’s. Note that All nodes are being previewed live on the graph canvas, each node displays it’s preview, and the material preview viewport on the left shows the proper end result:
Now compare that to the exact same parameter values from a MPC using CollectionParameters:
The preview viewport on the left shows the end result correctly, but none of the nodes on the graph update their individual previews. If I was to right click on the Lerp in the image above and choose “Start Previewing Node” the end result will preview correctly in the material preview viewport, but the node itself remains completely black in the editor graph.
No matter what you add to the node network it will always preview as 0-Black. As the node network starts to get more complicated can become a bit frustrating:
It seems like should be fairly easy to fix since you can preview it in the material viewport, so I would like to make a feature request to add in a live preview of MPC nodes using their default values set in the MPC. Hopefully isn’t too difficult to do, it would be a big help when building materials.
Let me know if you need any more info, thanks guys!