I know this isn't answering your question about Term::ReadKey, but....

Have you considered using a GUI, a Graphical User Interface, like Tk, Wx, Tkx, Gtk2, etc? Just in case you weren't aware that better ways exit for Pong, than just using a terminal. See PONG with TkZinc for example.

oh, thanks, but I was trying to write specifically a ASCII version :)

I think that I am reading your code correctly, if not, then ignore as appropriate.

When you are printing your movement, you are first clearing the old location, then writing to the new location. There is a period of time where the screen does not have the "sprite" displayed. With graphics-based sprites, I believe that the correct solution is to xor at the new location, then xor at the old location. In your text based version, print to the new location first, then clear the old location. There may be some edge cases <update>especially when old and new overlap</update> that you need to consider.

It has been a number of years since I have tackled this problem, but I seem to remember it being a common one when moving blocks of stuff around the screen.

I solved this way:

#!/usr/bin/perl

start:
$|=1;

use Term::ReadKey;
ReadMode 3;
($w, $h) = GetTerminalSize;

$n = 0.97; #AI sternght
$l = 10; #difficulty

$x1 = $w/2; $y1 = $h/2;

@dxs = (-0.09, -0.08, -0.07, -0.06, -0.05, 0.05, 0.06, 0.07, 0.08, 0.0
+9);

@d = (0.05, -0.05);
$dx = $d[rand @d];
$dy = $d[rand @d];

$x = $w/2-5;

while (1) {

$key = ReadKey -1;

if ($key eq "d") {$x++; $x = $w-10 if $x > $w-10}
if ($key eq "a") {$x--; $x = 0     if $x < 0}

$s = " " x (($x1-5)*$n) . "[========]";
$s .= "\n" x $y1 . " " x $x1 . "o"; 
$s .= "\n" x ($h-$y1-4) . " " x $x . "[========]\n\nyou:\t\t$you\ncomp
+uter:\t$pc\n\r";
print $s;

$dx *= -1 if $x1 >= $w-1 || $x1 <= 0;
$dy *= -1 if  ($y1 >= $h-5 && $x1 > $x && $x1 < $x+10) || ($y1 <= 1 &&
+ $x1 > (($x1-5)*$n) && $x1 < (($x1+5)*$n));
$dx = $dxs[$x1-$x] if  ($y1 >= $h-5 && $x1 > $x && $x1 < $x+10) || ($y
+1 <= 1 && $x1 > (($x1-5)*$n) && $x1 < (($x1+5)*$n));

$x1 += $dx;
$y1 += $dy;

if ($y1 < 0) {ReadMode 0; ++$you; sleep 1; goto start} 
if ($y1 > $h-4) {ReadMode 0; ++$pc; sleep 1; goto start}

select(undef, undef, undef, 0.005/$l);
system('clear');

}

ReadMode 0;
[download]

saving everything inside $s (: now it works perfectly (it has some minor bugs, but whatever)

#!/usr/bin/perl

$|=1;

use Term::ReadKey;
ReadMode 3;
($w, $h) = GetTerminalSize; #get size of the screen

$x1 = 0; $y1 = 0; #ball start coordinates
$dx = 0.05; $dy = 0.05; #increments to the ball coordinates

$x = 0; #start position of the pad

while (1) {

$key = ReadKey -1;

if ($key eq "d") {$x++; $x = $w-10 if $x > $w-10} #moving the pad to t
+he right
if ($key eq "a") {$x--; $x = 0     if $x < 0} #moving the pad to the l
+eft

print "\e[H"; print "\n" x ($h-2); print "\r\e[K"; print " " x $x; pri
+nt "##########\r\e[H"; #drawing the pad at the bottom of the screen

for (0..($h-3)) {print " " x ($w); print "\n"} #cleaning the screen ab
+ove the pad
print "\e[H\n\n\n"; print "\n" x $y1; print " " x $x1; print "O\r"; #d
+rawing the ball

$x1 += $dx; #update coordinates of the ball
$y1 += $dy;

$dx *= -1 if $x1 >= $w-1 || $x1 <= 0; #if the ball hits the left or ri
+ght wall
$dy *= -1 if $y1 <= 0 || ( $y1 >= $h-5 && $x1 > $x && $x1 < $x+10 ); #
+if the ball hits the top wall or the pad

if ($y1 > $h-4) {ReadMode 0; die "\nyou lose!\n"} #if the ball doesn't
+ hit the pad

}

ReadMode 0;
[download]