Multiple creators

[vpontis]

We want a way of storing multiple creators on an NFT.

This is useful for:

• showing that multiple people were involved with the NFT (can add them as signers)
• paying out royalties
• giving more than one person auth for modifying the NFT

Questions

1. should creators be on the collection or NFT level? or both?
2. should creators and royalties be combined into one PDA or should royalties be in a separate PDA?
3. should we indicate on the NFT that the NFT has royalties? it could be an extra flag
4. what should the unit of royalty be?
   • basis points — 1 / 100th of 1% so 10,000 basis points which requires u16 rather than u8

Spec

ix_nft_setup_creators

• check all the royalties add up
• store if there are / are not royalties
• store the overall royalty amount that the NFT should have
• verified creators should be signed
• update the NFT to store royalties_enabled

ix_nft_update_creators

• reset creators to new value

is_nft_add_creator

• should be signed with the new, verified creator

Future

• add this to Mintlist
• allow setting creators on the collection level rather than NFT level

Misc

Related to #11

[vpontis]

Tests

• adding creators works
• you can't add verified creators that haven't signed
• the basis points add up to 10k