Flash MX 2004 Games : Art to ActionScript

Flash MX 2004 Games
Figure 8.9 How two movie clips can overlap
The smaller movie clip A can be positioned in one of 10 possible places, in relation to the
larger B.
1 No Overlap
2 Top Left
3 Middle Left
4 Bottom Left
5 Top Middle
6 Inside
7 Bottom Middle
8 Top Right
9 Middle Right
10 Bottom Right
If we were totally general and allowed the case where movie clip A can be bigger than movie
clip B then there would be other cases, but for now we will only consider the case where both
the width and height of clip A is less than clip B.
Table 8.3 gives the conditions that will identify the placement of the smaller movie clip in
relation to the larger one; we use (left1, top1, right1, bottom1) to define the rectangle for A and
(left2, top2, right2, bottom2) to define the rectangle for B.
Apart from the special case of ‘No overlap’ it takes four tests to determine the location; we need
to test for the left, top, right and bottom of the first movie clip in relation to the second. The
location determines which of these tests we need to do. If we first check the ‘No overlap’ case
and find that this does not apply then we need to identify which of the nine other cases is the
112