Graphic sizing and output settings ..using illustrator

    hello,

  I’m having trouble atm trying to figure out how to size my objects in my app to fit my screen. I know how to create objects and put them in my scenes but im clueless on output size and how to correctly size them with my background or other objects. I use adobe illustrator and when I’m finished with my object graphic, I chose save for web since its the only option to save in .png. I’m just wondering how do you all output your graphics? I know I can eventually get the size where I want but I cant see everyone doing the same method as I am where I have to guess and save every time and see if it fits correctly in each scene. Like if I did wack-a-mole and my mole.png needs to fit perfectly with the hole in the scene. If anyone happens to know of any tutorials on graphics output and sizing I would much appreciate it.