Scratch

coolhogs wrote:

Hello Scratchers of Help With Scripts,
I am trying to make a physics game... I know people have posted this a hundred times but... I need a great, long, hard script for friction and gravity... I think I already have gravity... but it needs friction... 

Friction is usually done by taking your velocities and multiplying them by a number x where 0<x<1.  Usually, .9<x<1 is a good place to start, since anything lower than .9 slows the sprite down extremely fast.  All you do for a script is:

set [xvel v] to ((xvel) * [.95])

I also have a script on my test account that allows you to pick a top speed and a friction to determine how much each press of a key should change your x and y. Here

I've learned it's to everyone's advantage to compile everything you can in one script:

when gf clicked
forever
 if <key [right arrow v] pressed?>
  change [xvel v] by (1)
 end
 if <key [left arrow v] pressed?>
  change [xvel v] by (-1)
 end
 set [xvel v] to ((xvel) * (.87))
 change x by (xvel)
 if <touching [level v]?>
  change y by (([abs v] of (xvel)) + (1))
  if <touching [level v]?>
   change y by ((0) - (([abs v] of (xvel)) + (1)))
   change x by ((0)-(xvel))
   set [xvel v] to ((xvel) / (2))
  end
 end  
 if <key [up arrow v] pressed?>
  change y by (-1)
  if <touching [level v]?>
   set [yvel v] to (10)
  end
  change y by (1)
 end
 if <(yvel) < [3]>
  change y by (-1)
  if <not<touching [level v]?>>
   change [yvel v] by (-1)
  end
  change y by (1)
 end
 set [yvel v] to ((yvel) * (0.9))
 change y by (yvel)
 if <touching [level v]?>
  change y by ((0) - (yvel))
  set [yvel v] to ((yvel) / (2.5))
 end
end