Scratch

Can you explain further?

Use the following script and make the balls blue:

when gf clicked
forever
 if <touching color [#0000FF]>
  turn cw (180) degrees
   repeat until <touching color [#0000FF]>
    move (10) steps
   end
 end
end

How would I do that?  And sonicgames20's script won't work.

Assuming you have a sprite for a sircle, or a set of coords, you can work out the distance (scratch has a block for sprite distance, but the formula for coords is harder), do this:
sqrt of (playerx - circlex)^2 + (playery - circley)^2
Effectively the Pythagoras theorem. After you have the distance you check if the distance is less than the radius, then simply do your turning script (change direction, bounce off etc)

Implementation of amercbu's method. circle's center is the circle sprite, and padding is the amount of extra space you want between the circle and the sprite. Circle radius is the radius of the circle.

when gf clicked
forever
if <(distance to [circle's center v]) < (circle's radius)>
change x by (([cos v] of (direction)) * ((distance to [circle's center v]) + (padding)))
change y by (([sin v] of (direction)) * ((distance to [circle's center v]) + (padding)))
end
end

Last edited by bobbybee (2012-07-08 15:35:29)

Wait.  What's padding?

After it bounces, how far will it move away

when gf clicked
forever
if <([distance v] to [circle centre v]) < (radius)>
point in direction ((direction) * (-1)
move (10) steps

By point away, do you mean in the opposite direction, or just off to the side

point in direction ((direction) * (-1))

amcerbu wrote:

You can also point towards the center of the circle and turn 180 degrees for a roughly approximate bounce.  The actual physics are a bit more complicated (although I can explain them, if you want).

Well you could do that with a bit more complexity:
1) store your direction in variable (old)
2) point towards the center of the circle
3) turn (direction - old) degrees

That should work for a pretty accurate bounce.

There was one SDS project with circle bouncing.  What was that script?