Flash MX 2004 Games : Art to ActionScript

Chapter 18: Sports simulations
For much of the time the camera is scaled as in Figure 18.4 with the centre located in the middle
of a triangle that includes the two players with focus and the ball. This movement is achieved using
the ‘move’ function for the ‘Pitch’ clip. All the players and the ball are children of the ‘Pitch’ clip.
Because the players with focus change regularly and yet we do not want the camera view to jump,
we calculate a ramp between the positions using the ‘movecount’ variable. Whenever the player
with focus changes the ‘movecount’ variable is set to the value of the constant PANFRAMES.
A first call to the ‘move’ function with ‘movecount’ equal to PANFRAMES gives a value for a
of 1 and a value for b of 0. The x and y values are calculated using the ramp value.
1 function move(){
2 //Position the pitch so that it is centred around
3 //the ball and the nearest player and opponent
4 if (_root.playerTeam==_root.RED){
5 x = eval("Red" + _root.playerNo)._x;
6 x += eval("Blue" + _root.opponentNo)._x;
7 y = eval("Red" + _root.playerNo)._y;
8 y += eval("Blue" + _root.opponentNo)._y;
9 }else{
10 x = eval("Red" + _root.playerNo)._x;
11 x += eval("Blue" + _root.opponentNo)._x;
12 y = eval("Red" + _root.playerNo)._y;
13 y += eval("Blue" + _root.opponentNo)._y;
14 }
15
16 scale = _xscale/100;
17
18 x = (x + Ball._x)/3;
19 x = 270 - x *scale;
20
21 if (movecount>0){
22 a = movecount/_root.PANFRAMES;
23 b = 1 - a;
24 x = b * x + a * _x;
25 }
26
27 if (x>-247 && x0){
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