Hopalong

Press the space bar to generate a new image. (Click inside the image first so that the page has the focus).

The Armchair Universe is a 1988 book by A.K. Dewdney, a collection of his Computer Recreations columns that appeared in Scientific American in the early 1980s. Hopalong is one of the programs described in the chapter Wallpaper For The Mind. The chapter describes several algorithms for generating interesting graphics from simple iterative numerical procedures.

I’m not sure how to describe the patterns that Hopalong creates. Some of them are sort of kaleidoscopic, some are kind of crystalline, some are kind of cellular, and all of them have an odd asymmetry.

My version of Hopalong only creates black and white images for now, but I’m still fooling around with different ways of coloring the images, based on some suggestions in the book.

The program uses three randomly generated factors a, b, and c to create each image, and I display the value of the factors underneath the image, to be able to repeat one of them.