Each of the frames of this animation were generated using PHP and the GD library.

1. The first triangle constructed is called a supertriagnle. It is an equalateral triangle that entirely contains the convex hull of the points to be triangulated. The vertices of this construction will be removed in the last step, leaving the triangulated network.
2. Points to be triangulated are added one by one. The list of points is ordered by their y co-ordinate.
3. The horizontal red line shown in the animation shows the advancing front. This is a horizontal line passing through the y co-ordinate of the most recent point added to the network.
4. Circumcircles pass through the three vertices of each triangle in the network. As each additional point is added to the structure, triangles who’s circumcircle contains the new point are identified. These circumcircles are drawin in red and their associated triangles highlighted yellow and removed.
5. New triangles are formed between the most recently inserted point and the segments of the void left after removing the flagged triangles.
6. The speed of the algorithm is improved by flagging all triangles who’s circumcircle is entirely behind the advancing front. Triabngles below this line no longer require testing in point 4 above. These are identified in green and then added to the pool of dark grey triangles that no longer need to considered with the addition of each new point.
7. After the final point is added, the vertices of the supertriangle and any triangles that share these vertices are removed.

Web Of Life Website Thumbnail

Another option was to manually use the Print Screen key while each webpage is being shown in the browser, but with 6500 links in the directory, this would be very time consuming indeed, especially if I were to repeat the task periodically as I intend to.

After almost giving up on the idea I stumbled upon the Page Snapshot class at phpclasses.org. I found that code to be bloated and cumbersome, but it did lead me along a path that lead to a solution. The Page Snapshot class executes a command vie the exec command in PHP that requests a given URL in a web browser, it then waits a predetermined amount of time and takes a screen capture using Hypersnap. I used this same process, rewriting the code to suit my needs.

Hypersnap can be invoked via the command line and the file save format and capture area can be specified via command line options, making it a suitable tool for my needs. Used in conjunction with NMBot my screen capture process obeys robots.txt rules.

Website Thumbnail for the Beach Hotel Merewether

My PHP script allowed 20 seconds for all of the pages elements to be rendered, so the entire process took about 36 hours to complete. The thumbnails will be used on the Newcastle Music Directory website in the near future.

Here’s a video showing the first 4000 or so thumbnails:

Edit – April 2010: I never ended up using the thumbnails on the site.