Event (vuo.event)

Nodes for working with events, which control the timing of when different parts of a composition execute.

Events are a fundamental concept in Vuo. They’re what make things happen in a composition. For more information, see the Vuo Manual.

Some of these nodes fire events in response to certain basic activity as a composition is running, such as when the composition first starts or when the display refreshes.

To fire events at certain time intervals, see the vuo.time node set.

Many other node sets also have nodes that fire events (for example, in response to activity from a device).

Example compositions:

• Load Image Asynchronously: Downloads an image from the internet and displays it. While waiting for the image to download, displays a placeholder image.
• Load Image Asynchronously and Show URL: Displays an image URL and, meanwhile, downloads the image and displays it when available.
• Scale Rectangle When Value Edited: Changes the size of a rectangle layer when you drag a slider in the Vuo editor.
• Spin Kaleidoscope: Applies a kaleidoscope effect to an image. This composition demonstrates the best way to fetch an image (or do other one-time tasks) within an image generator or image filter — use an Allow First Event node instead of a Fire on Start node. Image by Pexels on Pixabay
• Spin Psychedelic Checkerboard: Each time the mouse is clicked, the checkerboard rotates several degrees, leaving a trail behind it. The trail forms because the checkerboard is actually rotated in several small increments per mouse click, with image feedback applied to each one.
• Store Count: Displays an increasing value alongside a saved value. When releasing a mouse click, the next value is stored and displayed.

Nodes:

• Allow Changes (vuo.event.allowChanges2): Outputs the input value when it changes.
• Allow First Event (vuo.event.allowFirst): Allows one event through, and blocks all events after that.
• Allow First Value (vuo.event.allowFirstValue): Allows one event through, and blocks all events after that.
• Are All Hit (vuo.event.areAllHit.2): Outputs true if both input ports receive the same event, and false otherwise.
• Became False (vuo.event.becameFalse2): Outputs an event when the input changes from true to false.
• Became True (vuo.event.becameTrue): Outputs an event when the input changes from false to true.
• Block Empty List (vuo.event.emptyList): Outputs the input list only if it contains at least one item.
• Changed (vuo.event.changed2): Outputs an event when the input changes to a different value.
• Decreased (vuo.event.decreased2): Outputs an event when the input changes to a lower value.
• Fire on Display Refresh (vuo.event.fireOnDisplayRefresh): Fires an event when the display is ready for the next frame.
• Fire on Start (vuo.event.fireOnStart): Fires an event when the composition starts.
• Fire when Value Edited (vuo.event.fireWhenValueEdited): Fires an event when Value is changed in the Vuo editor.
• Increased (vuo.event.increased2): Outputs an event when the input changes to a higher value.
• Share Event (vuo.event.share): Outputs the input event.
• Spin Off Event (vuo.event.spinOffEvent2): When this node receives an event, it fires a separate event.
• Spin Off Events (vuo.event.spinOffEvents): When this node receives an event, it fires multiple events.
• Spin Off Value (vuo.event.spinOffValue): When this node receives an event, it fires a separate event with that same value.