ASCII Ball in Box Animation

Question

Write a program that displays a moving ASCII ball * inside a rectangle (20 by 10 chars including border). The ball must not cross the rectangle, e.g. bump off when it hits the wall. The scene must be cleared and redrawn every 0.1 seconds and the ball must move 1 char in x and y direction every frame. The shortest program written in any language wins.

Example output (frame 1)

+------------------+
|*                 |
|                  |
|                  |
|                  |
|                  |
|                  |
|                  |
|                  |
+------------------+

Example output (frame 2)

+------------------+
|                  |
| *                |
|                  |
|                  |
|                  |
|                  |
|                  |
|                  |
+------------------+

Example output (frame 8)

+------------------+
|                  |
|                  |
|                  |
|                  |
|                  |
|                  |
|                  |
|       *          |
+------------------+

Example output (frame 9)

+------------------+
|                  |
|                  |
|                  |
|                  |
|                  |
|                  |
|        *         |
|                  |
+------------------+

Answer 1

Ruby 1.9, 115 characters

The movement logic is quite similar to Danko's answer.

This version has been tested on Linux only.

p=0
loop{u=(?|+?\s*18+"|
")*8
u[165-21*(7-p%14).abs-(17-p%34).abs]=?*
p+=1
puts"\e[2J",r=?++?-*18+?+,u,r
sleep 0.1}

Answer 2

Powershell, 144 characters

Based on Joey's excellent answer, using the fact that the ball coordinates are a function of the frame index (i), so if you have something like x=n-abs(n-(i mod (2*n))), x will go from 0 to n, back to 0, and so on...

for(){cls
($l="+$('-'*18)+")
7..0|%{$j=$_
"|$(-join(17..0|%{'* '[$j-[Math]::abs(7-$i%14)-or$_-[Math]::abs(17-$i%34)]}))|"}
$l;$i++;sleep -m 100}

Answer 3

Python 2, 234

I'm sure this can be golfed more, but I gotta go so here's what I have sofar. will work more on it later

import os,time
a,b,c,d,e,n='+- |*\n'
w=d+c*18+d+n
s=a+b*18+a+n
x,y=0,0
g,h=17,7
j,k=1,1
while 1:
 if 0>x or x>g:j*=-1;x+=j
 if 0>y or y>h:k*=-1;y+=k
 os.system('cls');print s+w*y+d+c*x+e+c*(g-x)+d+n+w*(h-y)+s;x+=j;y+=k;time.sleep(0.1)

note: works on Windows command console. Other operating systems may use a different command than cls to clear the screen, such as clear

Answer 4

Ruby (179 174 147)

EDIT got rid of some more chars:

l=?++?-*18+?++?\n
c=?|+?\s*18+?|+?\n
p=22
u=v=1
loop{f=l+c*8+l
f[p]=?*
puts"\e[2J"+f
p+=(u=f[p+u]==' '?u:-u)+21*(v=f[p+21*v]==' '?v:-v)
sleep 0.1}

EDIT shaved off some chars, now 174:

l="+#{'-'*18}+\n";f=l+"|#{' '*18}|\n"*8+l;x=y=u=v=1
loop{f[21*y+x]='*';$><<"\e[2J\e[f"+f;f[21*y+x]=' '
u=f[21*y+x+u]==' '?u:-u;v=f[21*(y+v)+x]==' '?v:-v
x+=u;y+=v;sleep 0.1}

Ungolfed:

l="+#{'-'*18}+\n"           # top and bottom lines 
f=l+"|#{' '*18}|\n"*8+l     # complete box as string
x=y=u=v=1                   # x,y position; u,v next move
loop {                      #
  f[21*y+x]='*'             # add ball to box
  $> << "\e[2J\e[f"+f       # clear screen and print box with ball
  f[21*y+x]=' '             # remove ball from box
  u=f[21*y+x+u]==' '?u:-u   # next move in x direction
  v=f[21*(y+v)+x]==' '?v:-v # next move in y direction
  x+=u                      # perform move
  y+=v                      # --"--
  sleep 0.1                 # .zZZ...
}                           #

Answer 5

JavaScript (275 283)

s=Array(19).join(' ');n='\n';z=Array(9).join('|'+s+'|'+n).split(n,8);
x=y=0;a=b=1;t='+'+s.replace(/ /g,'-')+'+';
setInterval(function(){u=z[y];z[y]=u.replace(eval('/( {'+x+'}) /'),'$1*');
$('#o').text(t+n+z.join('\n')+n+t);z[y]=u;x+=a;y+=b;if(!x|x==17)a=-a;if(!y|y==7)b=-b},100)

Demo: http://jsfiddle.net/eKcfu/2/

I wrote this up pretty quickly so I'm sure there's still quite a bit of room for improvement. Suggestions are welcome :)

Edit 1: Remove unnecessary separate function call, embed directly in setInterval.

Answer 6

Haskell, 212 characters

import System
main=mapM_ f$s 19`zip`s 9
s n=[2..n]++[n-1,n-2..3]++s n
f p=r"clear">>putStr(unlines[[" |-+*"!!(19#i+2*(9#j)+4*e((i,j)==p))|i<-[1..20]]|j<-[1..10]])>>r"sleep 0.1"
b#n=e$n<2||n>b
e=fromEnum
r=system

Uses a more functional approach for calculating the coordinates, by making the infinite sequence for each coordinate separately and then zipping them together (lines 2 and 3). The rest is drawing code.

Answer 7

PowerShell, 184 185 215

Only semi-golfed as my brain isn't working properly when I'm sick ...

A few nice tricks in it, though.

for($a=$b=1){cls
($l="+$('-'*18)+")
0..7|%{$j=$_
"|$(-join(0..17|%{'* '[$j-$y-or$_-$x]}))|"}
$l
$x+=$a;$y+=$b
if(-1,18-eq$x){$a*=-1;$x+=2*$a}if(-1,8-eq$y){$b*=-1;$y+=2*$b}sleep -m 100}

[Edit]: Looping over the field is much shorter.

Answer 8

QBasic (QB64), 178 173 bytes

a$="+------------------+
?a$
for c=1to 8
?"|                  |
next
?a$
do
x=19-abs(17-(i mod 34))
y=9-abs(7-(i mod 14))
locate y,x
?"*
_delay .1
locate y,x
?" "
i=i+1
loop

-5 bytes thanks to DLosc

Answer 9

Perl 5, 141 characters

print"\e[H\e[2J",$h="+"."-"x18 ."+
",(map{"|".$"x$q,(abs$t%14-7)-$_?$":"*",$"x(17-$q),"|
"}0..7),$h,select'','','',0.1while$q=abs$t++%34-17,1

Does not start on the upper left corner as the example output does, but that is not stated as a requirement.

Answer 10

Ruby 1.9, 162 characters

35 chars shy of @Ventero's answer, but I was impressed that I could get it down this far while still using a relatively straightforward approach to the actual logic. The ^[ is a literal ESC (1 char).

x=y=0
v=h=1
s=' '
loop{puts"^[[2J"+b="+#{?-*18}+",*(0..7).map{|i|"|#{i!=y ?s*18:s*x+?*+s*(17-x)}|"},b
y+=v
y+=v*=-1if y<0||y>7
x+=h
x+=h*=-1if x<0||x>17
sleep 0.1}

Answer 11

R, 233 characters

s=c("\n+",rep("-",18),"+");for (j in 1:8){cat(s,sep="");cat(rep(c("\n|",rep("",17),"|"),j-1));cat(c("\n|",rep(" ",j-1),"*",rep(" ",18-j),"|"),sep="");cat(rep(c("\n|",rep("",17),"|"),8-j));cat(s,sep="");Sys.sleep(0.1);system("clear")}

Answer 12

Another bash entry - 213 204 chars

Not really a prize winner, but it was fun nonetheless. It uses vt100 char sequences for the drawing. (the code reported here uses 215 chars for readability, 2 chars can be removed by escaping, e.g. '*' -> \*

e(){ printf "\e[$1";}
e 2J;e H
h='+------------------+'
echo $h
for((;++j<9;));do printf '|%18s|\n';done
echo $h
e '3;2H*'
while :;do
e 'D '
((i/17%2))&&e D||e C
((++i/7%2))&&e A||e B
e 'D*'
sleep .1
done

Answer 13

Powershell, 139 bytes

Inspired by Danko Durbić's answer.

for(){cls
,"+$('-'*18)+
"*2-join("|$(' '*18)|
"*8-replace"^(\W{$(21*[Math]::abs(7-$i%14)+[Math]::abs(17-$i++%34))}.) ",'$1*')
sleep -m 100}

This script uses the -replace operator to draw * inside the rectangle.

Less golfed script to explain how it works:

for(){
    cls
    $y=[Math]::abs(7-$i%14)
    $x=[Math]::abs(17-$i++%34)
    $b="+$('-'*18)+`n"
    $m="|$(' '*18)|`n"*8-replace"^(\W{$(21*$y+$x)}.) ",'$1*'
    ,$b*2-join($m)          # draw it
    sleep -m 100
}

Answer 14

Bash 278 300, 296

h="+------------------+"
w="|                  |"
g(){
echo -e "\e[$2;$1H$3"
}
g 1 1 $h
for i in {1..8}
do
echo "$w"
done
echo $h
x=4
y=4
p=1
q=1
for((;;))
do
((x==19&&p==1||x==2&&p==-1))&&p=-$p
((y==9&&q==1||y==2&&q==-1))&&q=-$q
x=$((x+p))
y=$((y+q))
g $x $y \*
sleep .1
g $x $y " "
done

The \e in the line echo -e "\e[$2;$1H$3" can be produced by

echo -e "\x1b"

to replace it. As binary 0x1b it is 3 chars shorter; I count just 1 for "\e", because only the layouting software forces me to use \e.

Answer 15

TI Basic, 169 167 bytes

1→X
1→Y
1→S
1→T
While 1
ClrHome
Output(Y,X,"*
S(X>1 and X<20)+(X=1)-(X=20→S
T(Y>1 and Y<10)+(Y=1)-(Y=10→T
X+S→X
Y+T→Y
For(N,1,20,19
For(O,1,10,9
Output(O,N,"+
End
End
For(N,2,19
For(O,1,10,9
Output(O,N,"-
End
End
For(O,2,9
Output(O,1,"|
Output(O,20,"|
End
End

Horribly slow, but it works.

Answer 16

PHP, 196 186 148 bytes

I removed avoiding an integer overflow to save 6 bytes. It will run for 29 billion years before overflow; still 6.8 years on a 32 bit system. I´d say that´s acceptable.

Calculating the position instead of adjusting it saved a lot, preparing the complete template at once another lot.

for(;++$i;$s[-3-21*abs($i%14-7)-abs($i%34-17)]="*",print$f(_,9e5,"
").$s.$z,usleep(1e5))$s=($f=str_pad)($z=$f("+",19,"-")."+
",189,$f("|",19)."|
");
").$z;

Run with -nr. Requires PHP 7.1.

breakdown:

for(;++$i;      # infinite loop:
                    # 2. set asterisk at appropriate position
    $s[-3-21*abs($i%14-7)-abs($i%34-17)]="*";
                    # 3. clear screen: print 900k newlines
    print$f(_,9e5*0+2,"\n")
            .$s.$z, # 4. print field
    usleep(1e5))    # 5. sleep 100000 microseconds
                    # 1. create template
    $s=($f=str_pad)($z=$f("+",19,"-")."+\n",189,$f("|",19)."|\n");