I do what I can, I do what I must

An algorithm inspired by artist Bridget Riley


A hexagonal grid of circles, generated quite simply in Grasshopper.

Early in 2016, with digital processes on my mind shortly after starting a laser cutting business, I wanted to learn how to write custom scripts that would run in Grasshopper. I invented a project that involved a close study of a work by artist Bridget Riley. At the time, I was struggling with the notion of authorship now that computer-generated and digitally fabricated artworks could easily become a part of my painting practice—that is, if I wanted them to. Riley’s works seemed to balance hard-edged repetitive, very scripted-looking structures with a certain degree of inventiveness that I found reassuringly non-computational. As a result, I wanted to try to uncover the nuances of her logic. Where did it loop, what were the exceptions, and how? And could this process be documented?

In an interview with Robert Kudielka, Riley denounces the relationship of her work to computers as “superficial and misleading”. I thought it would be most appropriate and equally ridiculous to write a script that attempts to replicate one of her works. I chose “White Discs 1”, painted in 1963.

My script defines a grid of circle centers, then defines the neighbors of each center. A radius value is selected from a weighted list of four values (A, B, C and 0) so that the radius does not equal that of any of its neighbors, except for 0 which is allowed to repeat.

It was interesting to find that the more inclusive the neighbor definition became (8 neighbors as opposed to 4, last image), the more a pattern began to assemble from what should have been random inputs. This occurred because the requirements became more difficult to fulfill, so it was more probable that a certain arrangement of circles would end up working together. The pattern breaks up near the edges where there are fewer neighbors and thus more freedom.

Regarding the Bridget Riley resemblance, it soon became clear to me that, while it approximates the basic qualities of the original, my script would need to be a bit more complex to capture the nuance of the composition. Is it the placement of the small dots in relation to the large ones? Or the subtle forming of diagonals across the picture? I’m not quite sure. Riley says, “You can’t experience those black-and-white paintings if you only count and measure their elements instead of seeing what they do.” I believe my simple experiment underpins this sentiment; however, I do believe that Riley underestimates the capabilities of computing—or rather, humans who compute. If the code writer can indeed ‘see what they do’, it should be possible to ‘do it’ computationally. At least in the case of the formal arrangements of Riley’s paintings (to say nothing of the extreme level of craft executed by her studio assistants who paint them), it’s just a matter of seeing.

And finally, I wonder, is it blasphemous to the history of painting to perform such a demeaning analysis? Probably—but it was still interesting to me as a fellow painter and digitally empowered human in 2016.

Iteration 1: four neighbors

Iteration 1

Iteration 2: four neighbors again

Iteration 2

Iteration 3: eight neighbors

Iteration 3

Further reading

Next project: Garden generator