Simple Onchain Widget

First make sure your Players can Connect their Wallet, you are Casting to the Player principal to the Game Instance and that you are aware of the Player TX UI/UX

To enable players to invoke a Transaction on the Stacks blockchain, via your UE5 based game, the Player should have their Wallet Connected and you've will Cast the Player Principal (with server authority assuming you are developing a multiplayer game) to the Player State through the Game Instance and Player Controller.

You are going to need to have Simple Widget UMG for the player to interact with and click Send with, we will call this widget our WB_Simple_Onchain_Widget

This documentation not go over all the details of creating a Unreal Engine UMG, there are plenty of examples of this already out there.

We will instead go over all the details related to what happens when you click the "Send" button in the WB_Simple_Onchain_Widget

Once your UMG Design is ready, you'll need update the Event Graph, specifically On Click Event handling for when the Send button is clicked. Select your Button, then in the Details panel, click the + Button to add the On Click event handler to your Event Graph.

The user clicks the "Send" button, which is wired to a Launch URL node (eg upon click the user is opening their browser at your Bridge App URL with something like)

https://your.bridge.url/?payload=%7B%22request%22%3A%22send%22%2C%22amount%22%3{TX_Amount}%2C%22to%22%3A%22{TO_Principal}%22%2C%22from%22%3A%22{PS_Principal}%22%2C%22isSTX%22%3Atrue%7D

(note: the URL has JSON encoded into it, thats why the extra padding characters exist, this will updated as time permits and should be easier on the eyes once updated)

We Drag off the On Click Event node, Cast to BP_PlayerController to get the Players State, then Cast to BP_PlayerState_Cryptonauts (your custom PlayerState class) so we can "As BP PlayerState Cryptonauts" extract the PS_Principl and use it as our from principal in our URL Arguements. We use String variables to concat (Append) the string into its final format before passing it to Launch URL. Replacing TX_Amount, TO_Principal, variables with your expectations (note: Amount should be micro STX denomination, eg no decimals)

We now have everything we need (in terms of Arguments, we have the TX_Amount TO_Principaland of course the players principal (PS_Principal) as the from principal in our URL arguments.