The UBF Previewer is a dedicated tool designed to streamline the content creation process by allowing creators to visually inspect UBF artifacts in real time. It serves as a crucial component of the UBF workflow—with the option to integrate directly with UBF Studio—to ensure that assets, blueprints, and instances function correctly before being integrated into an experience.

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Installation and Setup

Install UBF Previewer from Asset Creator Pack. In the pack, you will find the latest available version of UBF Studio and UBF Previewer for both Windows and Mac.
After installation, the UBF Previewer is ready to launch and can be opened like any other application on your system.

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Welcome to the UBF Previewer

Opening the UBF Previewer presents you with a dedicated environment for testing and validating your UBF creations. At the top left corner of the Previewer interface, you can inspect the current version of both the Previewer and the UBF Interpreter it is leveraging. This ensures that you are always aware of the specific interpreter version being used, which is useful for debugging and compatibility tracking.
ubf-previewer
A core component of the Previewer is the viewport (in blue) - which gives you the ability to navigate freely through a 3D, including rotating, panning, and zooming to inspect your creation from different angles. This allows for an in-depth visual review of your assets and their composition. At the bottom of the viewport, you can find two useful tools for testing:
  • Log Console – Displays any errors, warnings, or messages raised during your preview session.
  • Turntable – Allows you to start or stop the automatic rotation of your spawned asset, enabling a continuous 360-degree view.
The Previewer operates in two core modes - Live Connection Mode & Standalone Bundle Mode.

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Live Connection Mode

Live Connection Mode enables a direct link between the UBF Previewer and UBF Studio, allowing you to visualize changes in real time as you create or modify Blueprints and Blueprint Instances. By eliminating the need to repeatedly export artifacts, this mode dramatically speeds up iteration: any adjustment to a parameter, addition of a node, or reconfiguration of a Blueprint in Studio immediately appears in the Previewer. This rapid feedback loop is particularly valuable during early development and prototyping, where you may frequently adjust variables—such as colors, materials, or mesh placements—and want to assess those changes without the overhead of full export cycles.\

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Establishing Live Connection

To enter Live Connection Mode, first ensure that UBF Studio is running and that you have an open project. In the UBF Previewer, locate the Live Link button at the top right of the viewport. Selecting this option will prompt you to switch into Live Mode—confirm by clicking Yes.
ubf-live-connection
The Previewer’s interface will then update to reflect live view mode, indicated by a connection status in the bottom-left panel.
ubf-connection-status
Simultaneously, if you switch back to UBF Studio, you will notice a Preview button in the top-right corner of the Blueprint Editor screen.
UBF-view-preview
Pressing this button within any blueprint/blueprint instance pushes your changes to the Previewer for immediate review.
UBF-preview

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Standalone Bundle Mode

Standalone Bundle Mode allows you to load exported UBF bundles directly from your local disk, rendering them in the Previewer exactly as they would appear when interpreted by a UBF-compatible application. This approach is particularly valuable for the final verification of assets—once you’ve finished authoring and refining them in Studio, you can confirm their quality and functionality without the overhead of a live connection or additional integration steps. This mode is especially beneficial when you’re looking to review published content, test entire collections and even inter-project render testing - i.e. Preview how items from different projects might be combined.

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Loading Bundles

To load bundles in Standalone Bundle Mode, simply click the Bundle Loader icon—located in the bottom-left corner of the Previewer interface.
UBF-execute
This opens the Bundle Loader, where you can select one or more exported UBF bundles from disk. Each loaded bundle grants you access to its Blueprints and Blueprint Instances as well as all referenced resources, allowing you to preview multiple assets or entire collections simultaneously. Within the Bundle Explorer, clicking the ‘+’ button allows you to add a new bundle by selecting the path to a previously exported UBF bundle.
UBF-bundle-explorer
Once loaded, each bundle is represented as an entry with three key interactions:
  1. Bundle Information Panel – Displays details on how the bundle was loaded, including which Blueprints or Instances it contains, along with any warnings or errors encountered during the process.
  2. Update Bundle Path – Lets you modify the file path if the bundle’s location changes or you need to reference a different version.
  3. Remove Bundle – Deletes the bundle entry from the Previewer, ensuring you don’t accidentally spawn assets from an outdated or irrelevant bundle.
Once a bundle is successfully loaded through the Bundle Explorer, all Blueprints and Instances contained within that bundle become available to the Previewer. You can freely mix and match assets across any loaded bundles in your session, effectively creating a unified set of content to work with. This seamless integration allows you to spawn, combine, and validate items from different bundles in a single environment—ideal for testing cross-project assets or complex scenarios where multiple collections may interact.

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Previewing Loaded Blueprints

Once a UBF bundle is loaded, the Previewer enables you to select and test any Blueprint or Blueprint Instance contained within. This interface provides a flexible environment where you can experiment with input values and immediately observe the results—without making any permanent changes to the original blueprint data.
previewer-inspector
At the top of the Blueprint Execution Panel, you’ll find the Root Selector, which allows you to choose the root blueprint or blueprint instance you wish to preview. This selection determines which asset is instantiated in the viewport and which parameters appear in the input section. Inputs Panel Once a root is selected, the Inputs section dynamically populates with all configurable inputs defined in that blueprint. These fields represent the parameters that the blueprint expects—such as textures, meshes, materials, or nested blueprint references. Each input is automatically pre-filled with its default value, if one has been specified in the blueprint. You can override any of these values directly in the panel using the dropdowns or text inputs, depending on the input type.
Changing input values in the Previewer does not modify the blueprint itself—it only affects the current preview session.
Outputs Panel Below the inputs section, the Outputs panel displays all outputs declared by the selected blueprint. This includes any properties or computed values that the blueprint exposes to other blueprints or systems. Reviewing the output state helps ensure your blueprint logic is functioning as intended and is producing the correct results. Executing the Preview Once you have configured the desired input values, click the Execute button to run the blueprint with your selected parameters. The viewport will update to reflect your changes, and any relevant logs or errors will be displayed in the console panel below.
previewer-render
This previewing mechanism enables rapid experimentation and debugging—ideal for fine-tuning visual elements, validating logic, and exploring how combinations of assets appear in context. By leveraging the Previewer, creators can test blueprints both in isolation and as part of larger sets, ensuring greater confidence before artifacts are deployed to production environments.