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#1 2008-02-09 12:47:02
- Lucario621
- Community Moderator
- Registered: 2007-10-03
- Posts: 1000+
Scripts in blocks
I am wondering, what formula could I use to simulate the block that says "if touching edge, bounce"?
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#2 2008-02-09 13:11:25
- Paddle2See
- Scratch Team
- Registered: 2007-10-27
- Posts: 1000+
Re: Scripts in blocks
It's fairly simple, if you are using velocity variables to control your sprites movement. Then, if it is a left or right edge, just multiply the horizontal velocity by (-1) to change the sign. If it is a top of bottom edge, multiply the vertical velocity by (-1).
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#3 2008-02-09 16:53:23
- Lucario621
- Community Moderator
- Registered: 2007-10-03
- Posts: 1000+
Re: Scripts in blocks
Not with veloctiy. With direction and move _ steps
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#4 2008-02-09 17:34:14
Re: Scripts in blocks
You will need to calculate which edge you are touching - so rather than using "if touching edge" use
If ABS(X)>239
> Point in direction (-1)*(direction)
> Repeat until ABS(X)<240
> > Move 5 (this part is to stop it from getting stuck)
If ABS(Y)>179
> Point in direction (180)-(direction)
> Repeat until ABS(Y)<180
> > Move 5 (this part is to stop it from getting stuck)
Enclose all that inside a loop, includeing "Move 5" at the start of the loop.
Example here:
http://scratch.mit.edu/projects/Mayhem/96405
Web-spinning Spider: http://scratch.mit.edu/projects/Mayhem/18456
3D Dungeon Adventure: http://scratch.mit.edu/projects/Mayhem/23570
Starfighter X: http://scratch.mit.edu/projects/Mayhem/21825
Wandering Knight: http://scratch.mit.edu/projects/Mayhem/28484
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#5 2008-02-09 18:00:59
- kevin_karplus
- Scratcher
- Registered: 2007-04-27
- Posts: 1000+
Re: Scripts in blocks
If you are using "move __ steps" then the bounce is just a change of direction.
If you are bouncing off a vertical edge, then the direction change is
set direction to -direction
If you are bouncing off a horizontal edge, then the direction change is
set direction to 180-direction
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#6 2008-02-09 19:30:37
- Lucario621
- Community Moderator
- Registered: 2007-10-03
- Posts: 1000+
Re: Scripts in blocks
Thanks guys,
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#7 2008-02-09 19:34:34
- Lucario621
- Community Moderator
- Registered: 2007-10-03
- Posts: 1000+
Re: Scripts in blocks
Honestly I was going to use it so if a ball was to touch the side of a rectangle it would bounce in the correct direction rather than pick random -40 to 40. :@
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#8 2008-02-09 19:44:20
Re: Scripts in blocks
My code can easily be adaped for that by changing the values that X and Y are checked against.
Web-spinning Spider: http://scratch.mit.edu/projects/Mayhem/18456
3D Dungeon Adventure: http://scratch.mit.edu/projects/Mayhem/23570
Starfighter X: http://scratch.mit.edu/projects/Mayhem/21825
Wandering Knight: http://scratch.mit.edu/projects/Mayhem/28484
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#9 2008-02-10 16:05:59
- Lucario621
- Community Moderator
- Registered: 2007-10-03
- Posts: 1000+
Re: Scripts in blocks
I thought so.
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