Touching ()? (block)

"Touching" redirects here. For the block that senses if a sprite is touching a color, see Touching Color ()? (block).

Touching ()?
touching ( v)?
Category	Sensing
Type	Boolean

The Touching ()? block is a sensing block and a boolean block. The block checks if its sprite is touching the mouse-pointer, edge, or another sprite (a reporter block which returns the sprite's name, usually a variable can be used). If the sprite is touching the selected object, the block returns true; if it is not, it returns false.

This block behaves differently when the sprite is hidden. Every check for collisions with other sprites return false, however, it still senses the mouse and the edges.

Detection

Whether or not a sprite is touching another depends on whether or not a part of the sprite's visual texture (defined by its Costume) is touching that of another. For example, if a sprite's Costume is that of a circle, it will have a circular hitbox when detecting if it is touching other sprites.

Note:

The collision detection data of this block can be finicky and inaccurate with large or moving sprites, particularly when applied to physics engines.

Example Uses

Because this block checks if its sprite is touching another sprite or an edge, it is widely used in detecting collisions.

Some common uses for the Touching ()? block:

• Moving a sprite until it touches the edge of the screen

repeat until <touching (edge v)?>
   move (3) steps
end

• Having a sprite chase another sprite until the chaser touches the other sprite

repeat until <touching (Sprite2 v)?>
   point towards (Sprite2 v)
   move (3) steps
end
say [I got you!] for (2) secs

• Stopping bullets when they hit walls

In this example, the wall is moving, and the bullet remains fixed.

forever
if <touching (wall v)?> then
hide

• In a maze, sensing if a sprite has hit a dead-end

forever
if <touching (maze walls v)?> then
say [Dead end!] for (1) secs

• Checking if a sprite is touching the mouse pointer

when flag clicked
forever
if <touching (mouse-pointer v)?> then
switch costume to (highlighted v)
else
switch costume to (normal v)
end

• Checking if the player has touched an enemy in a game

forever
if <touching (Enemy v)?> then
say [Game over!]
stop [all v]
end

Clones Touching Clones

Normally, most blocks targeting other sprites will not act on one of the sprite’s clones, but for the parent sprite. However, with this block, if <touching (sprite2 v)?> is used in a clone of sprite1, not only will it report true when touching the parent sprite, but also when touching any clone.

Related Suggestion

Some Scratchers want a block that detects if two different sprites are touching. The advantage of such a block is that it grants a 3rd sprite the ability to sense if another two are touching. Such a block would look similar to this:

<(sprite1 v) is touching (sprite2 v)? ::sensing>

This can be replicated with a global variable, with one of the touching sprites checking, and setting the value, like so:

// In Sprite1
when I receive [Check for Touching v]
 if <touching (Sprite2 v)?> then
  set [Sprite1 Touching Sprite2? v] to [yes]
 else
  set [Sprite1 Touching Sprite2? v] to [no]
 end


// Place this in any sprite to check for the touching
broadcast (Check for Touching v) and wait
if <(Sprite1 Touching Sprite2?) = [yes]> then
// put the desired output if touching here
else
// put what you want if they aren't here
end