Deborah R. Fowler
Squares Illusion (Modulus)
Posted Dec 27 2019
Updated Dec 8 2020 added animation video
Updated June 22 2023 added a new 3D animation (see bottom
of page)
Also on youtube at https://www.youtube.com/watch?v=wKpmDf5EYq8
Continuing with Illusions, from https://www.rd.com/article/optical-illusions/ I thought this looked like an excellent example to display modulus. Modulus is the remainder on integer division and made the recreation of this illusion easier to reproduce in Houdini.
As seen below, this illusion is using modulus.
To start, create a rectangle using an add
node. Clip node by 45 degrees on each end. Use modulus to apply
black to every other clipped rectangle. Copy that triangle to
create a larger triangle
Copy the compliment. Using modulus with source grid points,
select every other point, sort, and then every other point
again. Do this for both patterns.
Below is the node network:
Below is an animation of levels of "stripes".
Taking this one step further, copy these faces
onto the points of a cube to get a 3D version. The box faces are
scaled to zero in the primitive node and the points fused. The
settings for the fuse node are below.
Added June 23, 2023 a 3D animation from January
Also on https://www.youtube.com/shorts/CTqtFjv1PO4