Here I want to share share something with you guys, and it is about how to make a graphic/picture become transparent. In certain situation, you really need this kind of effect for example if you want to create an image of water/river/pond and so on.
In this example, firstly I draw a Moo image and water image and then combining them like the picture below (Water layer need to be placed above of the Moo layer).
In this example, firstly I draw a Moo image and water image and then combining them like the picture below (Water layer need to be placed above of the Moo layer).

After that, click on the water on the screen(still in Bitmap format) -> right click -> choose 'convert to symbol'.

Then choose 'Graphic' and give a name for the image. I renamed it as 'water'.

Now look at the 'Properties' at the bottom of the screen. At the 'Color Dropdown Menu', choose 'alpha'.

Then adjust the given percentage. Decrease the value until you satisfied with the result.

Finally..the processes are completed. Now you can see Moo's lower body through the water. Try it :)

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