Crosshair Targetting

You've probably seen this in a lot of shooting games. A crosshair follows the mouse around the screen. This tutorial demonstrates how to make horizontal and vertical lines follow the cursor.

Start a new movie.
Draw a horizontal line. Convert this to a Movie Clip symbol (F8).
Draw a vertical line and convert this to a Movie Clip as well.
Then draw a pair of concentric circles. Select both circles and convert these to a third Movie Clip.

Next, edit the properties of each symbol in turn (right-click on the symbol and choose Properties).
Give the symbols the Instance Names shown in the picture below.



Now Rename the layer containing all the graphics (call it 'Graphics'). You can rename a layer by double-clicking on its name on the right of the timeline.
Add another layer below this and give it the name 'Actions'. This is where the Actionscript is going to go.



Add the following actions to the keyframe at frame 1 of the 'Actions' layer.

The first line starts a drag on the circles, causing it to follow the mouse.
Choose the 'Constrain to Rectangle' option, and insert values which fit the size of your movie (or an area where you want to confine the crosshairs).
My movie is 400x300, so I chose those values to allow the crosshairs to move around the entire movie stage.
The remaining two lines reposition the two lines so that they are lined up across the circles.



The next step is to add a second frame to both layers on the timeline. Insert a second keyframe (F6) at frame 2 in the 'Actions' layer.
Put in the following code:

This causes the movie to loop back to the previous frame (so that the positions of the crosshairs are continuously updated).



And that's all there is to it!
One quick note: you might find that the default frame rate of 12fps is too slow for this. A higher rate such as 40fps will reduce any jerkiness.

The result should look something line the example below: