Creating Mask in Flash CS4

This entry is part 11 of 32 in the series Flash CS4 Tutorials

A mask is simply to hide or reveal certain parts of a layer, for lets say we import an image on stage, so go to File -> Import -> Import to stage like the one here
Creating Mask in Flash CS4
You have imported an image from your image file to stage, lets say you want to reveal a small portion of this image, you want to hide most of the picture, we need to create a mask to do that in Flash CS4, the way we need to do that is by creating another layer above the picture layer, lets first lock the picture layer and rename layer1 to picture and create another layer and name it mask, Now lets draw a mask, select the mask layer and draw a circle on stage by selecting a bright green color, it doesn’t matter what color you select, so draw the circle on stage for the picture you actually want to see, the mask is going to act as a flash light so whatever it touches is what we are going to see, having drawn a circle for the picture you want to see, you will see something like this
Creating Mask in Flash CS4
By doing this we actually don’t see the picture what we really wanted to see, the mask is not done yet, now click on the mask layer and right click on your mouse and select mask,
As soon as you do that you can see what we wanted to see like the picture below.

To do more practical illustration, lets draw a planet with a ring around it, so first draw a red circle, select the oval tool and select the color red and draw a circle on stage and call it planet in layer1, lock layer planet and insert a layer just above layer planet and call it rings, so by choosing a oval tool, we don’t need a fill color but we need a stroke color to this ring, make the thickness of the ring to 30 and draw a ring on stage, by selecting the oval shape and pressing alt and dragging it around the red circle you will get something like this below,
Creating Mask in Flash CS4
now make the ring to a fill instead of a stroke, we can do so by first select the black ring in the rings layer and by going to the main menu-> Modify->Shape-> convert Lines to fills.

We need to create a mask and hike this section like this one here

Remember that while creating a mask you need to create a mask that you want to reveal and not the parts you want to hide, so we don’t want the mask to touch the picture above but everything else other that that, so lets create a new layer and call it mask right above the rings layer, now copy the rings layer and paste it in the mask layer by going to the rings layer, select the ring, press ctrl+c to copy it, lock the rings layer, go to the mask layer and paste it exactly the same place as it was in the rings layer by pressing Ctrl+Shift+V, it will paste the rings in exactly the same position as it was in the rings layer, now be very careful and follow the step very carefully, lets lock the mask layer for a second, unlock the planet layer and using the lasso tool just copy the top part of the planet that is touching the ring, we are actually trying to cut out the ring that is supposed to go behind the planet,
Creating Mask in Flash CS4
We have made that selection now copy it from the planet layer by pressing Ctrl+c then lock the planet layer, go to the mask layer and unlock it and then paste it in the mask layer by pressing Shift+Ctrl+V, lets make the planet layer and the rings layer invisible by clicking on the eye icon on each layer to see what we have done in the mask layer.
Creating Mask in Flash CS4
Now that you have pasted the red cap which is interfering with the black ring you can select the red cap and delete it by pressing delete button, then your mask layer will look some thing like this below.

Now there we go, we see only the portion of the ring we need to see, now we can make all the layers namely, planet, rings and mask layer visible, but still you will see picture
Creating Mask in Flash CS4
That’s because we have not applied mask to the mask layer, now click on the mask layer, right click the mouse and select mask, that it you image will look something like this.