| If on Edge, Bounce | |
if on edge, bounce | |
| Category | Motion |
| Type | Stack |
| Introduced in | 10Jul04 (0.x) |
The if on edge, bounce block is a Motion Block and a stack block. The block checks to see if a sprite is touching the edge of the screen, and if it is, the sprite will point in a direction that mirrors the direction from which it was coming. It uses the edge as a mirror to determine the reflection angle. The block will also push the sprite out of the edge of the screen.
Example Uses
- Preventing a sprite from partially leaving the screen (often, this is followed by the Point in Direction block to stop reflection)
- Reflection
- Games such as "Pong"
- Allowing sprites to bounce off the screen:
- When the user wants a specific sprite to be in the screen without touching the edge.
when gf clicked forever move (10) steps if on edge, bounce
- It also works for games such as fish.
when gf clicked forever turn cw (pick random (-10) to (10)) degrees move (3) steps if on edge, bounce wait (0.01) seconds
Workaround
- Main article: List of Block Workarounds
This block can be replicated by detecting if the sprite is beyond the edge of the screen, and changing the sprite's direction if this is the case:
if <[240] < ([abs v] of (x position))> then
point in direction ((0)-(direction))
end
if <[180] < ([abs v] of (y position))> then
point in direction ((0)-(direction))
end
However, the workaround is not perfect, as it does not push the sprite out of the edge of the screen. Additionally, because the sprite's direction changes based on its coordinates rather than its actual shape, sprites with costumes not centered about the costume center may get stuck on the edge of the screen rather than bouncing off of it.
Bounce Block
Some users in the suggestions forum have requested a generalized bounce::motion block, which would allow sprites to bounce when they collide with other sprites or with colors.[1][2][3] The block, however, has been rejected, because of how ambiguous the implementation of such a block is.[4][5]
