Inspiration REFERENCE by Akiyoshi Kitaoka. Continuing with Illusions, this is a good exercise in problem solving and is a variation on the Autumn Illusion. The image below compares the two versions.
First, it's important in problem solving to break things into smaller pieces — modularity! The gif below steps through the construction of the illusion, showing how each layer builds on the previous.
The key to the illusion is the background colors. The foreground shapes themselves are identical — only the background changes, yet the center appears to shift.
Code from the point wrangle for the background:
Adding a parameter for the radius allows the effect to be animated, as seen below. Changing the radius dynamically reveals how strongly the background color influences the perceived position of the sun shape.
The illusion is created by these background colors as seen in the images below.
You could also use this to create a "moving square" illusion. Below is the wrangle for the circular version:
To square:
