Challenge

The shortest program by character count that accepts standard input of the form X-Y R, with the following guarantees:

• R is a non-negative decimal number less than or equal to 8
• X and Y are non-negative angles given in decimal as multiples of 45° (0, 45, 90, 135, etc.)
• X is less than Y
• Y is not 360 if X is 0

And produces on standard output an ASCII "arc" from the starting angle X to the ending angle Y of radius R, where:

• The vertex of the arc is represented by o
• Angles of 0 and 180 are represented by -
• Angles of 45 and 225 are represented by /
• Angles of 90 and 270 are represented by |
• Angles of 135 and 315 are represented by \
• The polygonal area enclosed by the two lines is filled with a non-whitespace character.

The program is not required to produce meaningful output if given invalid input. Solutions in any language are allowed, except of course a language written specifically for this challenge, or one that makes unfair use of an external utility. Extraneous horizontal and vertical whitespace is allowed in the output provided that the format of the output remains correct.

Happy golfing!

Numerous Examples

Input:

0-45 8

Output:

        /
       /x
      /xx
     /xxx
    /xxxx
   /xxxxx
  /xxxxxx
 /xxxxxxx
o--------

Input:

0-135 4

Output:

\xxxxxxxx
 \xxxxxxx
  \xxxxxx
   \xxxxx
    o----

Input:

180-360 2

Output:

--o--
xxxxx
xxxxx

Input:

45-90 0

Output:

o

Input:

0-315 2

Output:

xxxxx
xxxxx
xxo--
xxx\
xxxx\

Perl, 235 211 225 211 207 196 179 177 175 168 160 156 146 chars

<>=~/-\d+/;for$y(@a=-$'..$'){print+(map$_|$y?!($t=8*($y>0)+atan2(-$y,$_)/atan2 1,1)&-$&/45==8|$t>=$`/45&$t<=-$&/45?qw(- / | \\)[$t%4]:$":o,@a),$/}

Perl using say feature, 161 149 139 chars

$ echo -n '<>=~/-\d+/;for$y(@a=-$'"'"'..$'"'"'){say map$_|$y?!($t=8*($y>0)+atan2(-$y,$_)/atan2 1,1)&-$&/45==8|$t>=$`/45&$t<=-$&/45?qw(- / | \\)[$t%4]:$":o,@a}' | wc -c
139
$ perl -E '<>=~/-\d+/;for$y(@a=-$'"'"'..$'"'"'){say map$_|$y?!($t=8*($y>0)+atan2(-$y,$_)/atan2 1,1)&-$&/45==8|$t>=$`/45&$t<=-$&/45?qw(- / | \\)[$t%4]:$":o,@a}'

Perl without trailing newline, 153 143 chars

<>=~/-\d+/;for$y(@a=-$'..$'){print$/,map$_|$y?!($t=8*($y>0)+atan2(-$y,$_)/atan2 1,1)&-$&/45==8|$t>=$`/45&$t<=-$&/45?qw(- / | \\)[$t%4]:$":o,@a}

Original version commented:

$_=<>;m/(\d+)-(\d+) (\d+)/;$e=$1/45;$f=$2/45; # parse angles and radius, angles are 0-8
for$y(-$3..$3){                               # loop for each row and col
    for$x(-$3..$3){
            $t=atan2(-$y,$x)/atan2 1,1;   # angle of this point
            $t+=8if($t<0);                # normalize negative angles
            @w=split//,"-/|\\"x2;         # array of ASCII symbols for enclosing lines
            $s.=!$x&&!$y?"o":$t==$e||$t==$f?$w[$t]:$t>$e&&$t<$f?"x":$";
            # if it's origin -> "o", if it's enclosing line, get symbol from array
            # if it's between enclosing angles "x", otherwise space
    }
    $s.=$/;
}
print$s;

EDIT 1: Inlined sub, relational and equality operators return 0 or 1.
EDIT 2: Added version with comments.
EDIT 3: Fixed enclosing line at 360º. Char count increased significantly.
EDIT 4: Added a shorter version, bending the rules.
EDIT 5: Smarter fix for the 360º enclosing line. Also, use a number as fill. Both things were obvious. Meh, I should sleep more :/
EDIT 6: Removed unneeded m from match operator. Removed some semicolons.
EDIT 7: Smarter regexp. Under 200 chars!
EDIT 8: Lots of small improvements:

• Inner for loop -> map (1 char)
• symbol array from split string -> qw (3 chars)
• inlined symbol array (6 chars, together with the previous improvement 9 chars!)
• Logical or -> bitwise or (1 char)
• Regexp improvement (1 char)
• Use arithmethic for testing negative angles, inspired by Jacob's answer (5 chars)

EDIT 9: A little reordering in the conditional operators saves 2 chars.
EDIT 10: Use barewords for characters.
EDIT 11: Moved print inside of loop, inspired by Lowjacker's answer.
EDIT 12: Added version using say.
EDIT 13: Reuse angles characters for fill character, as Gwell's answer does. Output isn't as nice as Gwell's though, that would require 5 additional chars :) Also, .. operator doen't need parentheses.
EDIT 14: Apply regex directly to <>. Assign range operator to a variable, as per Adrian's suggestion to bta's answer. Add version without the final newline. Updated say version.
EDIT 15: More inlining. map{block}@a -> map expr,@a.