Flash MX 2004 Games : Art to ActionScript

Flash MX 2004 Games
49 }else{
50 flip[6] = false;
51 }
52 if (scanBoard(row, col, piece, opponent, -1, 1)){
53 legal = true;
54 flip[7] = true;
55 }else{
56 flip[7] = false;
57 }
58
59 return legal;
60 }
Listing 16.5
As you can see from Listing 16.5 the meat of the legal move checker is the function ‘scanBoard’.
Listing 16.6 shows the function in full. Notice how parameters five and six are used in a repeat
loop checking for the existence of an opponent’s piece. There must be at least one piece so if none
is found the function returns false. If there is an opponent’s piece then the values for ‘incX’ and
‘incY’ are added repeatedly until the condition fails. At this point we check that the end of the
line contains a player’s piece; if this is true then this direction contains a line that is suitable.
1 function scanBoard(row, col, piece, opponent, incX, incY){
2 var x, y, name;
3
4 x = col + incX;
5 y = row + incY;
6 name = "board" + y + "_" + x;
7
8 //Must be at least one
9 if (eval(name)._currentframe != opponent) return false;
10
11 while(eval(name)._currentframe==opponent){
12 x += incX;
13 y += incY;
14 name = "board" + y + "_" + x;
15 }
16
17 //Next piece must be a piece frame
18 if (eval(name)._currentframe == piece) return true;
19
20 return false;
21 }
Listing 16.6
250