Palette Cycling

Overview

Change the palette, not the pixels. Palette cycling animated graphics by shifting colour indices through different values—what was blue becomes green becomes yellow becomes red, cycling endlessly. Water appeared to flow, lights seemed to pulse, and fire flickered, all without redrawing a single pixel.

The principle

Step	Process
1	Design image with gradient colours
2	Assign sequential palette indices
3	Each frame, shift palette values
4	Pixels appear to move

Common effects

Effect	Implementation
Flowing water	Blue gradients cycling
Fire/lava	Orange/red palette rotation
Glowing lights	Brightness cycling
Neon signs	Colour pulsing
Waterfalls	Vertical flow illusion

Technical advantages

Benefit	Explanation
Zero CPU redraw	Only palette changes
Tiny memory	No frame storage
Smooth animation	Limited only by refresh rate
Multiple effects	Different palette ranges

Platform implementations

Amiga

The Copper could change the palette per scanline. Colour registers live at $DFF180-$DFF1BE (32 entries × one word each). Cycling means writing the same range each frame with the values rotated by one slot:

; Rotate colours 1-7 for a "flowing" effect
; (palette[1] becomes palette[2], palette[2] becomes palette[3], etc.)
            move.w  $dff182,d0          ; Save palette[1]
            move.w  $dff184,$dff182     ; palette[1] <- palette[2]
            move.w  $dff186,$dff184     ; palette[2] <- palette[3]
            ; ... etc through palette[7] ...
            move.w  d0,$dff18e          ; palette[7] <- saved

The Copper can additionally swap palettes mid-frame for per-scanline cycling (e.g. waterfall sprite columns where each row uses a different rotated palette).

PC (VGA)

DAC register manipulation:

256-colour palette
Direct register writes
Smooth transitions

C64

Limited but possible:

16 fixed colours
Software cycling
Character colour attributes

Limitations

Constraint	Impact
Fixed design	Must plan for cycling
Colour usage	Dedicates palette entries
Art constraints	Limits general colour use
Directional only	Can't change shape

Famous examples

Game	Effect
Monkey Island	Ocean waves
King's Quest	Waterfalls
Deluxe Paint	Animation tool
SimCity	Water features

Animation without redraw