FPP
Flexible Pixel Position
The most permissive of the C64 vertical tweaks: every single pixel line of graphics placed anywhere on screen, independently of every other — so graphics can be reversed, repeated or stretched at will.
FPP — Flexible Pixel Position — is the end of the road for the C64’s vertical screen tweaks:
FPP means the ability put every single pixel-line of graphics vertically on the screen independently of any other pixel-line.
What it adds
FLD moves blocks of eight pixel rows and keeps them in order. FPP drops the ordering constraint entirely:
Where as with FPD the lines always keep the same order, with FPP you can turn your graphics upside down, display it tripple times, stretch it or whatever.
Once any line can go anywhere, the effect stops being “scrolling” and becomes arbitrary vertical resampling — the basis of wobbles, mirrors and the vertical distortion effects that define late-1980s C64 demos.
It is a family, not a routine
“FPP can be obtained in a few different graphic modes… so basically you choose one from what kind of graphics you have.” Codebase64 carries separate treatments for the first line, the last line, sprite FPP, and an FLI-FPP scroller that combines it with FLI.
Who did it first
Bones, with Triangle 3532 and Upfront, in Random — 26 June 1989. Credited to a coder and two groups jointly, which is itself typical of how the scene recorded authorship.
See also
- FLD — coarser, order-preserving, and forgiving
- FLI — the colour equivalent
- Linecrunch