My ball won't come back ~ LOL

[jolly50]

Hey,

I'm working on some animation and i'm close to figuring it out, but i still have a while to go....

code:

setscreen ("graphics") var x :int x:=0 loop drawfilloval (x,200,100,100,brightblue) delay (10) drawfilloval (x,200,100,100,white) x:=x+5 if x >maxx then     drawfilloval (x,200,100,100,brightblue)     delay (10)     drawfilloval (x,200,100,100,white)     x:=x-5 end if end loop

I know it has something to do with the if statement....

What do i have to fix to make this work?

[Clayton]

Look closely at your if statement. If your ball goes beyond maxx, then you subtract 5 from it's x value. Afterwards, you assume you're below maxx, so you add 5 again, and this process just keeps on going in an infinite loop. Try using a velocity variable to keep track of whether you should add or subtract to your x position.

[CodeMonkey2000]

Basically (as Clayton said) make a variable called xIncrement (this is x component if your velocity). This will initially equal 5. Your x value will increase by xIncrement every time you go through the loop. If there is a collision, xIncrement should equal the negative of itself (ie. xIncrement=xIncrement*-1). And that's it.

[jolly50]

So... something like this?

code:

setscreen ("graphics") var x :int var vx: int x:=0 vx:=-5 loop     drawfilloval (x,200,100,100,brightblue)     delay (10)     drawfilloval (x,200,100,100,white)     x:=x+5         if x>maxx then         x:=x+vx         end if end loop

but the ball still wont come back?

[HeavenAgain]

change your if statement to

code:

if x >= maxx then         vx := -5     elsif x <= 0 then         vx := 5     end if

and your condition for x to

code:

x:=x+vx

im just "fixing" your code, but this is not the best way to do this kind of grahpics, im sure...
look up on View.Update to fix the flicker problem
and some other stuffs....

[CodeMonkey2000]

And that can be further broken down to

code:

if x >= maxx or elsif x <= 0 then          vx=vx*-1          end if

[Clayton]

A slight modification:

Turing:

%draw the ball, etc. ... %update ball's position x += vx if x <= 0 or x >= maxx then     vx *= -1 end if

EDIT: Fixed comments to be lead in by a %, not //

[CodeMonkey2000]

Set the vx to 5 before entering the loop, or else it will get stuck.

[jolly50]

ok, So i figured out my code...problem is.... I need help with the flicker....

code:

setscreen ("graphics") var x, y :int var vx, vy: int x:=0 vx:=5 y:=0 vy:=Rand.Int (1,10) loop     drawfilloval (x,y,100,100,brightblue)     delay (10)     drawfilloval (x,y,100,100,white)     x:=x+vx     y:=y+vy         if x>maxx then         vx:=-5            elsif x<0 then         vx:=5         end if                 if y<0 then         vy:=5         elsif y>maxy then         vy:=-5         end if end loop

Sorry if I'm getting aggravating....I'm just really interested in animation!

[HeavenAgain]

HeavenAgain @ Mon Nov 05, 2007 8:51 pm wrote:

change your if statement to
look up on View.Update to fix the flicker problem

oh my god, im quoting myself

code:

View.Set ("offscreenonly") View.Update

add viewset at the beginning of your code, and viewupdate before delay, or play around with it, i dont know

[Clayton]

Take a look at my tutorial in the Turing Walkthrough for View.Set() and View.Update(). That should answer all of your questions.

[Zampano]

That's good except there's probably one frame where the ball appears to be offscreen; the frame where the ball first goes offscreen. To solve that, why not rearrange your ifs and your drawfillovals? Then you use some math to restart the ball at the very edge of the screen.

[jolly50]

THANKS HeavenAgain!!!! it worked great!!!! and thanks to the all the rest of you for all your help!!!