Simple rotational procedure in mode 13h
Posted on 1998-12-19
My objective is to have a SIMPLE (keyword, not FAST) procedure written entirely in pascal. I've found most rotate procedures on the 'net are written in asm. Unfortunately, i have no knowledge there.
Anyhow, I've seen many methods discussed for doing this.
Apparently, the method of just transferring a pixel from the picture to it's new location leaves holes. But if you work backwards, pic the new location, then look back to see what color pixel is there, you can fix this problem nicely. Or something along those lines.
The farthest i've been able to get in any sort of rotational thing would be to draw a circle. Or should i say, rotate a point a set distance around the center. (I hear there is a different 'circle' formula)
At any rate, if someone could supply a SOURCE for doing this, it would be great. You can really just put pixel's onto the screen and rotate them, I can always put in an image file loader later.
Most importantly, this has to be SIMPLE please. No need to use lookup tables or anything, calculate the sin/cos everytime. My goal here is to understand it.