[Chicago] My mind is not seeing it

[Adam Bain]

Randy,

I don't see the bug exactly as you describe it. What I see is the ball
speeds up only when hitting the paddles (not when hitting the gutter, I
tried letting the ball hit the gutter a lot and saw no velocity increase
until I hit it with a paddle).  This seems to be the intended behavior as
you increase the horizontal component of the velocity by 10% each time
theres a paddle hit.

ball_vel[0] = ( -ball_vel[0] ) * 1.0

This horizontal speed does not get reset in magnitude after a point is
scored but it does get reversed (this doesn;t really affect the bug, but I
can't really tell if this is intended) :

else:
            ball_vel[0] = ( -ball_vel[0] )

To get to the meat of the bug though, what is happening is that you are
multiplying up the magnitude of the horizontal by 1.1 each hit (e.g 4,.4.4,
4.84, ~5.32, ~5.86, ~6.44, ~7.09). As you noted this does eventually go
above 7, but consider what the code does in that situation.

if ( ball_pos[1] <= bottom1 ) and ( ball_pos[1] >= top1 ): # You hit left
paddle
    # increase abolute velocity 10 percent but to no more than 7
            print ' hit paddle '
            if abs( ball_vel[0] ) < 7:
                ball_vel[0] = ( -ball_vel[0] ) * 1.1

This means that when the paddle is lined up for a hit, it will pass the
first if, print the 'hit paddle' and then fail the second if condition,
which means the ball never gets reversed.

To the second part of your question, I assume you are asking why this
eventually gets counted as a point.  This is simply because as the ball
goes through the paddle, it will eventually no longer satisfy the first if
condition of being between the two paddle boundaries (especially since ht
user wont be able to see the ball anymore) and will fall through to the
else, which will run the 'point scored' code,

There are a couple of simple ways to close this bug (depending on how
strictly you want to enforce the 7 speed limit), but rather than spelling
them out for you hopefully, this helps you getting on the right track to
coming up with a solution. Post back if you're still having trouble.


Adam Bain


On Wed, Jan 16, 2013 at 11:41 AM, Randy Baxley <randy7771026 at gmail.com>wrote:

>
> Would someone play this game and tell me why towards the end the ball
> speed increases when hitting the gutters and fails the test when hitting
> the paddles and then passes the test?
>
> http://www.codeskulptor.org/#user8-paYp6vO6lS-19.py
>
> TIA,
>
> Randy
>
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>
>
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