Step Four: The ActionscriptNow the set up is all done we will add all the actionscript. To understand exactly how the slider works you need to understand a little actionscript. We will use the 'globalToLocal' movie clip method. This action is a way of converting the coordinates of one movie clip to new coordinates that are relative to the coordinates of another movie clip. We will convert the coordinates of the slider to coordinates relative to the paths coordinates. In essence this means our return value will be number between 0 and the number you specified as the right 'x' coordinate of the path.
Select the slider instance and add this code under the onClipEvent(load) action
1. Use the onClipEvent(enterFrame) action (Actions <%gt%> onClipEvent), this means this code will continually be run
2. We are creating a new object to hold our new coordinates information. Use objects <%gt%> object <%gt%> newObject to add this line and give the object a name, I have simply used 'a'.
3. The next two lines set the x and y properties of our new object to the x and y coordinates of the slider.
4. This is where we add the globalToLocal (objects <%gt%> movieClip <%gt%> globalToLocal) method which converts the coordinates to coordinates relative to the path Movie Clip.
5. Lastly we convert newObject (a) 'y' coordinate into a useable variable 'b'. It involves a little maths and tinkering with. In my example my MovieClip to scroll is twice as long as my path therefore the code b = int(a.x * 2); makes the b value twice as much as the a.x value meaning my movieClip will scroll 2 pixels for every one pixel the slider moves along the path. The 'int' in front of the formula just converts the answer to an integer and is purely cosmetic.
|» Level Intermediate|
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