An arc is a curve. All arcs have a width, which is the distance between the starting and end point. Arcs also have a apex or depth.
Imagine a pie and you are going to cut a slice. The point of the piece of pie is the center of the pie; the arc is the crust. Three sets of numbers are used for arc. The first x y set is the center.
The distance from one side of the crust to the other is the width of your arc and is the third number. The bigger the number the bigger piece of pie you get.
The distance from the center to the arc is the apex or depth and is the fourth number. Do you have a nine inch pie or a twelve inch pie?
In this example, the center of the arc is 150x150, the width of the arc is 50 and the depth is 50.
//imagearc ($im, 150, 150, 50, 50, 0, 180, $black);
The last two numbers are the beginning and ending points of of your crust, in other words, where on the pie does your arc begin?
ALLarcs begin at the 3o'clock position (Image Magick calls this east) and they are drawn CLOCKWISE.
So an arc going from the top to the bottom curving OUT would have a beginning point of 270, and an ending point of 90.
These are the same shapes as in previous lessons. We just add arc. Here is an arc chart to guide you. ARCS
This definitely takes some practice but just remember two things: 1. ALL ARCS BEGIN AT 3O'CLOCK
2. ALL ARCS DRAW CLOCKWISE