Graffiti and Math

Author: Muter

In the Graffiti Grapher software we will use Cartesian coordinates to locate the start and finish of each line. Each coordinate is a pair of numbers. The X coordinate tells you how far left or right. The Y coordinate tells you how far up or down. Cartesian coordinates use both negative and positive numbers, so don't forget to use the "-" sign.

The most important lines in Graffiti Grapher are the borders. Every two borders gives you a "shape." A collection of shapes is called a "group." Here is a group of two shapes. Shape 1 has green borders, shape 2 has red borders.

Now that you've seen how to indicate location based on a pair of values (Cartesian Coordinates), it's time to look at a different way to express location on a grid - Polar Coordinates. Polar Coordinates use an angle and a distance from a center point (known as the origin) to determine location.

With an origin consisting of x and y coordinates, a distance r, and an angle a, you describe a polar coordinate.

Some of the curves in graffiti are arcs of spirals. The radius for the arc of a circle never changes, but the radius of a spiral arc changes as the arc moves from one endpoint to another. Depending on how quickly the radius changes we call the arc different things.

Some arcs change radius by a factor of about 3 (2.7), we call these log spirals. These spirals grow at a rate controlled by a value C. They have a starting radius of “size” and start facing a certain direction and then go around in an arc until it reaches a given angle. As you draw you may want to change the width of your pen. You can use negative pen growth to shrink the pen, and positive to make it grow.

When using the pen, you can use the "set pen color" block to change the pen color.