The Amiga Boing Ball demo was created during a night at the 1984 CES by Dale Luck and R. J. Mical and it is told that show visitors completely blown away by this.
The demo itself was a very clever demonstration of how it's custom chips could be used to fake an effect rather than to create it with pure processing power.
In reality nothing on screen is redrawn during the demo.
The ball itself is rendered at the beginning of the demo and then 'animated' with the color cycling method.
The motion of the ball is done by moving the scroll positions of the different bitplanes. It uses 3 bitplanes, while the grid uses another bitplane and the shadow uses the last bitplane.
The clever selection of color registers makes it possible to have a shadow that works correctly with the grid while not interfering with the ball. This is also the reason why this image needs 32 colors and why the color palette contains mostly duplicates.
All this means that the demo does full hardware scrolling, costing next to no cpu processing power.