The correct title of this article is Backdrop # (block). The Scratch Wiki uses this different title because of technical restrictions.
This article is about the block. For more information on the value this block reports, see Costume Number (value).
Backdrop #
2.0 Backdrop Number.png
Category Looks
Type Reporter
Introduced in 2.0

The Backdrop # block is a Looks block and a reporter block. This block holds the current backdrop number. It appears only in the stage's block palette; however, the Backdrop Name block appears in both the stage and sprites. (Background # can also be used in a sprite by dragging it from the stage's palette.) The equivalent for sprites is Costume #, which, conversely, cannot be used in the stage; if tried, a script error will be thrown.

This block can be displayed as a stage monitor.

History

Prior to Scratch 2.0, this block was called Background #. (Unlike the other backdrop blocks, only its name was changed, not its function.) During the development of Scratch 2.0, this block was available to both the stage and sprites.

Example Uses

As this block holds the backdrop number of the Stage, it is used when something must happen if the Stage is at a specific backdrop. Some more common uses:

  • Stopping the project once the Stage reaches the backdrop for the end of the project. This is helpful because it will automatically stop the project when that backdrop is reached.
when gf clicked
wait until <(backdrop #) = (6)>
stop [all v]
  • Checking what the current backdrop is
say (join [The current backdrop is: ] (backdrop #))
  • Setting a variable to the backdrop scene
set [level v] to (backdrop #)

Workaround

Main article: List of Block Workarounds

This block can simply be replicated with the following code

([backdrop # v] of [Stage v])

This workaround is useful whenever a sprite needs to detect the current backdrop number.

See Also