Unreal Engine: How to Add Widgets With C++ at Runtime

Let’s say you have an existing UMG UI which you’ve created in C++ already* (derived from UUserWidget), and you want to add child widgets at runtime. Imagine you have an inventory UI with a container of some kind (I’ll use a vertical box in this example) and you want to add an item at which the player is aiming. You could add a method to your UUserWidget-derived class like this (I’ve used a text block for the example but you can use any widget derived from UWidget):

void UMyUserWidget::AddInventoryItem(FText ItemName)
    auto NewInventoryItemWidget = WidgetTree->ConstructWidget<UImage>();

That’s it!

* Mike Stevanovic has a great tutorial for creating UUserWidgets and adding them to the viewport using C++.

How to Create a Circle Crosshair in Unreal Engine

This tutorial shows you how to create a circular crosshair using a widget blueprint with a material. As always, there are many methods available but this one has some key advantages:

  • Material parameters let you modify the crosshair in realtime. In this tutorial we will use a material parameter to optionally fill the circle.
  • No texture manipulation needed with external software.
  • The colour of the crosshair can be easily changed, both in the editor and during runtime.

This is what the final crosshair will look like. I’ve wired up the “F” key to fill the crosshair for demonstration purposes, but my game will ultimately fill the inside when the player is aiming at an interactable object.

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