Tutorial Update: Basic Blit with Transparency

Tutorial Update: Basic Blit with Transparency

Super cool 8bitrocket.com reader, MR. K, asked a very interesting question today. He asked if this tutorial included transparency because both the screen background and the helicopter background are black. Some how I completely missed that point when I created the original tutorial. The answer is that of course blitting can be done against a complex background with transparency, but the sprite sheet I used was didn’t have any transparency, and my background was just a black square. Opps!

Sure enough, the original tile sheet was a png file, but it had a solid non-transparent background. So, I opened up the tile sheet in Fireworks, selected the background with the selection tool and deleted it out. I saved it off as a png file and re-imported it into Flash. The new file looks like this:

Since our site has a dark gray background, you can tell right away the difference between that file and this one from the original tutorial.

The difference is HUGE. As the original file created a set of sprite tiles with a big black square around them.

I also created a 400×400 background tile to use as a background:

When they are put together, they look like this:

Very few code changes were needed, I just referenced a library item as the background instead of instantiating a black square. The tile sheet in my code was already set to use transparency, so no other changes were needed.

All of the new source files are here

If you enjoyed this post, please consider leaving a comment or subscribing to the RSS feed to have future articles delivered to your feed reader.
This site is protected by Comment SPAM Wiper.