Command Palette

Command Palette is a free and open-source editor plugin for Unreal Engine. It’s a utility window for quick access to assets, calculator, and Blueprint variables.

This plugin was made in a week as part of my self-study at university, and my first experience writing C++ in Unreal Engine.

Features

Technical Implementation

The plugin is designed for easy extensibility. It uses the Provider pattern, where the command palette window holds a list of providers:

TArray<USearchProvider*> SearchProviders;

USearchProvider is a base class that has a virtual HandleSearch function:

class COMMANDPALETTE_API USearchProvider : public UObject {
	GENERATED_BODY()
public:
	virtual SearchProviderResult HandleSearch(const SearchProviderContext& context) {
		checkNoEntry(); // *Unreal's way of forcing derived classes to implement this function
		return {};
	}
}

*Due to Unreal’s reflection system, pure virtual functions (= 0) are not allowed. checkNoEntry() is used instead. It triggers a runtime error if a derived class fails to implement the function.

Derived classes must implement HandleSearch, which fires each time the user types in the command palette. The context contains the search query and other relevant information, and the function returns a list of search results that are then displayed in the command palette window.

It’s up to the provider to decide how to handle the search query and what type of results to return. This makes it easy to add new functionality to the command palette by simply creating a new provider and implementing the search logic.

Having spent this extra time on making the plugin easily extensible, I was able to, within a week, add new features to the command palette by simply creating new providers and implementing the search logic in the HandleSearch function:

• Asset Search: Uses the IAssetRegistry to search for assets.
• Calculator: Uses the FBasicMathExpressionEvaluator to evaluate math expressions.
• Variable Search: Uses the Unreal reflection system to search for Blueprint variables.

This also allows other developers to easily extend the command palette with their own custom providers without having to modify the existing codebase.

Conclusion

For a first week with C++ in Unreal Engine, I’m happy with how the architecture turned out. The Provider pattern kept things clean and made adding features genuinely easy. Possible extensions include editor command execution, recent files, and settings search. The list goes on. Each would just be a new provider.

Command Palette is free and open-source. Feel free to try it out, contribute, or build your own providers on top of it.