Scratch

thanks so much!

music_man wrote:

That is an easy way to make gravity.  Hope this works for you!

That is not a very efficient way of doing gravity and by the looks of it the script will make a sprite move at a constant speed which may not be something you want for realistic looking gravity.

The cleaner the code the better 

Last edited by archmage (2007-11-23 16:24:14)

I have made a simple gravity demo for you which includes bounce.
http://scratch.mit.edu/projects/archmage/58354

Now bouncing on angles in more difficult because it involves trigonometry.

Check out http://scratch.mit.edu/projects/archmage/58354 for a simple bouncing script.

To bounce the ball, do this:

<forever if>  <touching color[  black
<set{  gravity  }to(  ((  <{  gravity  }>  <*>  -1  ))
<end>

funkymonkey's way to clean it up is good.  This one will make it bounce.

This may cause some problems just to let you know.  I have a project I will let you use.  It shows you how to make a ball bounce.  It is not on the web sight yet but it will soon.

Last edited by music_man (2007-11-23 23:13:48)

music_man wrote:

To bounce the ball, do this:

<forever if>  <touching color[  black
<set{  gravity  }to(  ((  <{  gravity  }>  <*>  -1  ))
<end>

funkymonkey's way to clean it up is good.  This one will make it bounce.

This may cause some problems just to let you know.  I have a project I will let you use.  It shows you how to make a ball bounce.  It is not on the web sight yet but it will soon.

If you want it to lose power do this


<forever if>  <touching[  ground
<set{  gravity  }to(  ((  <{  yVelocity  }>  <*>  -0.95  ))
<change{ yVelocity  }by( 1
<end>

This is what I have in my demo

Music_man's way was pretty similar but the object will not lose it's bounce power.

Last edited by archmage (2007-11-24 11:27:35)

funkymonkey wrote:

so that would make it like what you had in your project? for me to make something bounce i should use these 2 scripts:
[blocks]  <when green flag clicked>
<set{ yVelocity }to( 0
<forever>
<change{ yVelocity }by( -1
<change y by( yVelocity
<end>

<when green flag clicked>
<forever if>  <touching[  ground
<set{  gravity  }to(  ((  <{  yVelocity  }>  <*>  -0.95  ))
<change{ yVelocity  }by( 1
<end>
[/blocks]

i would need the variables gravity and yVelocity, and also a sprite called ground.

just clearing it up. thanks!

Oh, very sorry a part of the script is wrong.

It should have the yVelocity variable instead of the gravity variable

//Like this
<when green flag clicked>
<forever if>  <touching[  ground
<set{  yVelocity  }to(  ((  <{  yVelocity  }>  <*>  -0.95  ))
<change{ yVelocity  }by( 1
<end>

It would also be a good idea to set the yVelocity to 0 when the flag is clicked.

can you make the ball bounce other ways that just up and down? like since im making a soccer game, i need to be able to make the ball be able to move when it is hit.

kevin_karplus wrote:

For more complicated bouncing off of objects, check out the pinball game at
http://scratch.mit.edu/projects/kevin_and_abe/54377
It only works in scratch v1.2, but it has pretty good bounces with slow gravity.

what was the script that you used to make it bounce like that?

music_man wrote:

No.

actually thats basically what you said would make it bounce. archmage's scripts were the only ones that made it actually bounce.

Last edited by funkymonkey (2007-11-25 20:52:33)

music_man wrote:

Here is a way to do gravity:

  <forever if>  <not>  <touching color[  black
  <change{  gravity  }by(  -0.5
  <end>

  <forever if>  <touching color[  black
  <set{  gravity  }to(  0
  <end>

  <forever if>  <not>  <touching color[  black
  <set y to(  <{  gravity  }>
  <end>

  <forever>
  <if>  <key[  up arrow  ]pressed?>
  <change y by(  3
  <set{  gravity  }to(  8
  <wait until>  <touching color[  black
  <end>
  <end>

That is an easy way to make gravity.  Hope this works for you!

does this work for gravity? just for making the jump look more realistic. thats what i need now.

You might also want to look at the ball sprite in "School pinball"
http://scratch.mit.edu/projects/kevin_and_abe/54377