Variables

Variables hold values that can be read or written. Definition:

let name = value

This defines name with value value. value can be a Float, a Rect, or an expression that evaluates to one of those.

Variables can be redefined; only the last definition takes effect. Once defined, a variable can be used when creating elements or defining other variables.

Built-in variables

• t: current time in seconds
• top: ratio of actual height to actual width
• o: scroll offset
• joined: 1 if the user has joined the event, 0 otherwise
• $h: maximum scroll height; set this to limit how far the user can scroll

NOTE

UML itself has no event system. To create dynamic behavior such as animations or page switching, use t, o, and button press times.

Global variables

Global variables can be read or written anywhere in the UML file. Definition:

global name = @type

Here, type can only be btn. You can still assign to it with let; the last assignment wins.

NOTE

The event UI is redrawn every frame, so all variables are recomputed every frame as well. Some button properties need to persist across frames, so they are stored in global variables.