I’ve just been stepping into tinkering around with Processing, making code sketches.
Here’s the visual output:
Here’s the code. The first lines describe the area of the drawing: 600 pixels square, and the color of the background.
Each fill and ellipse function describe a new shape. I’ve given “fill” 4 parameters: red, green, and blue between 0 and 255. Fourth is opacity between 0 and 255. These settings will apply to the circle described next (and any until the next “fill”). I’ve given “ellipse” 4 parameters: x and y coordinates, then width and height.