Duplicate
Movie Clips
       by kirupa   |  2003

Many cool animations or special effects in Flash use the duplicate movie function. The duplicate movie, as its name implies, creates another copy of the movie clip and places the copied movie clip on stage. This tutorial will teach you how to create duplicates of a movie clip when a button is pressed.

Note
This tutorial is for Flash MX and earlier. For Flash MX 2004, visit the revised tutorial here.

The following animation is a good example of the duplicate movie clip function at work (press the plus sign to generate new movie clips):

 
 

[ press the plus sign to generate more movie clips ]

To make your strenuous programming life easier, I have provided an incomplete source file for you to work on. Don't worry, the source file does not include the ActionScript necessary to duplicate movie clips; you will enable that with information found on this site.

Download Incomplete FLA

Here is how to duplicate movie clips:

  1. Open the duplicate_tutorial.fla file you downloaded from the above link.
     
  2. Select the circle movie clip. Once the circle movie clip has been selected, click the Instance tab to display the Instance panel. In the Name field of the Instance panel, enter the word circle:

[ the movie clip has been given the name 'circle' ]

  1. Now that you have the circle movie clip named, it is time to add some actions to the button. Right click on the button and select Actions. The Object Actions window will appear. Copy and paste the following code into that window:
     

[ copy and paste the above code in the Object Actions window ]

  1. That's it! You are done with entering the code to create duplicate movie clips. Preview the animation and press the plus sign to see new movie clips.

How Does the Code Work?
The following section will basically deconstruct how the code you copied and pasted enables a new movie clip to appear:


on (press) {
    i = i + 1;
    duplicateMovieClip (_root.circle, "circle" + i, i);
}

 

The first line is the On handler for the button. Whenever the user presses the button, the code within the on (press) executes. In this case, a duplicate movie clip is created when the button is pressed.


on (press) {
    i = i + 1;
    duplicateMovieClip (_root.circle, "circle" + i, i);
}
 

This line contains a counter with the variable i. While I could use i++ to increment the value by one, I decided to expand i++ with i = i + 1 to make it easier for you to see that the variable increments each time the button is pressed.


on (press) {
    i = i + 1;

    duplicateMovieClip (_root.circle, "circle" + i, i);

}
 

Before I explain the intricacies of the blue colored code, let me furnish you with the generic syntax that the duplicate movie clip function follows:

    duplicateMovieClip (target, new mc name, mc depth);

The above code should be pretty self-explanatory. The target identifier is the name of the movie clip that you choose to copy. In our example, the movie clip, circle, was going to be copied; hence, _root.circle appears in the target place.

The second identifier gives a name to the duplicated movie clip. When a clip is duplicated, the new movie clip needs to be given a new name. You can enter the name as a string, or as an expression. In my code, the movie clip name is in the format of an identifier. Each time a new movie clip is generated, remember, the variable i increments by one. So, if there are 10 movie clips on stage, the last movie clip will be "circle" + i which is circle10. Therefore, the instance name of the 10th movie clip will circle10. Simple enough!

Movie depth refers to the vertical stacking order of the new duplicate movie clip. The higher the movie depth value, the higher up the movie clip will be on stage. In my example, each movie clip that is created will be higher than the previous movie clip because i is incrementing with each movie clip added onto the stage. To learn how to adjust the stacking order of movie clips, visit the following URL: //www.kirupa.com/developer/actionscript/swapdepth.asp

Movie Clip Actions
In the previous section, I explained the workings of the code inserted on the button. In this section, I am going to explain the code in the movie clip. The code in the movie clip was already there in the partial source, so don't worry if you do not remember adding that code....you didn't add the code!

Right click on the circle movie clip and select Actions. You will see the following code:

onClipEvent (load) {
   scale = (random(100) + 50)

   this._x = random(250);
   this._y = random(150);
   this._alpha = random(100);
   this._xscale = scale;
   this._yscale = scale;
}
 

The above code plays heavily into OOP (Object Oriented Programming). Because this tutorial does not focus on OOP, I will primarily point you to the following two lines of code:

   this._x = random(250);
   this._y = random(150);


When a new movie clip is created by using the duplicate movie clip function, the movie clip gets placed over the previous movie clip. If you don't have a variable that changes the scale of a duplicated movie clip, you will not notice any discernable change in your animation because all the new movie clips are being stacked on top of each other.

The aforementioned two lines of code applied to a movie clip enable the movie clip to be placed in a random location each time it is duplicated. That. Using the above code ensures that your movie clips are not stacked on top of each other. The values 250 and 150 correspond to the width and height of your movie respectively. You should modify that number so that a new movie clip gets randomly placed within the boundaries of your movie clip.

Adding Duplicate Movie Clip to a Frame
If you want to have duplicate movie clips appear automatically when an animation loads, use the following syntax:

amount = 50;
   while(amount>0) {
   duplicateMovieClip (target, new mc name, mc depth);
   i = i + 1;
   amount = amount-1;
}

Similar to adding actions for a button, use the above format to add the actions to a Frame. The value after amount = is the number of movie clips that will be generated. Adjust the number of movie clips you wish to duplicate by modifying that number.

Downloads
Even though I make every effort to make sure that my tutorials are legible and understandable for all users, I am also not infallible. Therefore, I have provided the final source code for you to see how the animation I used to write this tutorial turned out:

Final Source for this Tutorial

Conclusion
Duplicating movie clips is essential for your Flashing career. Many great animations use the duplicate movie clip function to create spectacular Flash effects. Many of the animations featured on the levitated.net site use the duplicate movie function along with numerous random algorithms to create unique animations: http://www.levitated.net

If you have a question about this or any other topic, the easiest thing is to drop by our forums where a bunch of the friendliest people you'll ever run into will be happy to help you out!

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