Programming in BASIC on the Color Computer - Spaceship Demo improved
12At the end of Chapter 22, covering GET and PUT, we did a DIY Spaceship demo that drew a ship in outer space that would fly up the screen across a background of planets.
There were some fancy techniques used here, because we employed page flipping, and getting and putting with the OR option to make the spaceship appear to be transparent.
Not being satisfied on how "lame" that looked, I took it upon myself to expand the features of this demo in a few ways.
I added starts to outer space, making it look more spacy. I took the original spaceship, created a reverse mask of it, and used that to blank out the background area behind the ship so it no longer looked transparent, it now looks like a solid, foreground object that also does not erase the background, thanks to page flipping, and getting and putting the original background back after peach composite.
This added overhead caused the program to run even slower, so the BASIC programmer's best friend, POKE 65495,0 was called in to save the day and speed up the entire program.
What we have now, is a faster and smother demo that looks much better than the original.
The techniques are described in this video in pretty good detail, and also are very thoroughly explained in the recent blog post about this updated demo:
http://ogsteviestrow.com/updating-the-rocketship-demo-the-anatomy-of-a-getput-demo/
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