When an MPC is selected as the Source Material Collection for an NPC, all of its current parameters are carried over to the NPC with their current values.
After that, if parameters are added to, removed from, or updated on the MPC, those changes do not get reflected on the NPC. Also, unlinking the source MPC from the NPC does not cause its parameters to disappear from the list.
Clearing and reselecting the source MPC on the NPC forces a partial resynchronization. New parameters are added with their current values. However, removed parameters are not removed, and changed parameters are not updated (unless they were manually removed before reselecting the source MPC). Moreover, the same problem as before continues from that point on.
If the NPC editor window is closed and reopened, nothing changes. The only way to force a complete resynchronization is to unlink the source MPC, manually delete all leftover parameters, and relink the MPC, which is very cumbersome for artists working with NPCs.
Note that, since unlinking the MPC does not remove the corresponding parameters from the NPC, selecting one MPC and then another results in the NPC having all the parameters from both.
1. Create a Material Parameter Collection (MPC)
2. Open the MPC and add two float parameters
3. Create a Niagara Parameter Collection (NPC)
4. Open the NPC and set the MPC as its Source Material Collection.
4.1. The float parameters on the MPC are correctly carried over to the NPC
5. Make each of the following changes to the MPC:
5.1. Delete a float parameter
5.2. Change the value of the other float parameter
5.3. Add a new float parameter
6. Note that none of the changes above are carried over to the NPC, even after saving the assets and/or closing and reopening the asset editors.
7. Unlink the MPC by clearing the NPC's Source Material Collection
7.1. The existing parameters on the NPC are unaffected (undesirable)
8. Create a new MPC, add a vector parameter, and link it to the NPC
8.1. The resulting NPC contains parameters from both MPCs that were linked to it at some point (undesirable)
Note: Some of the behaviors above might be by design currently, but they make the MPC+NPC workflow very cumbersome and even unreliable for artists.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-226010 in the post.
| 1 |
| Component | UE - Niagara |
|---|---|
| Affects Versions | 5.4.4 |
| Created | Sep 30, 2024 |
|---|---|
| Updated | Oct 29, 2024 |