Code and Football

This is a follow up on my three part article, “Drawing a good diagram of a football field“. After trying for some time to automate arrow drawing, I’ve come to the conclusion that using GIMP, an arrow drawing plug-in, and GIMP’s path tool (a way to draw both straight lines and curves) are adequate to handle this problem.

Needed:

1. Diagram Drawing Tools (see my three part series here, here, and here).
2. A copy of GIMP. It’s free and available on Windows, Mac, and Linux.
3. Some experience with layers on GIMP. Start by searching “How to use layers in GIMP”. There are some nice Youtube videos that can get you started here.
4. This article is also really good: “How to Draw Arrows in Gimp”. Get the arrow plugin, install it, and read the instructions.
5. Look further at GIMP pathing with the search: “using path tool in gimp”.
6. For dashed and dotted lines, search using this phrase: “dashed lines in gimp”.

Some notes about drawing diagrams. If you’re using Windows shell to draw, then you’ll have no issues with Image::Magick. If you want to use the Perl interface to draw, then switch to Graphics::Magick, a fork of Image::Magick. Image::Magick has bugs when used with Perl.

When drawing arrows on a 640×480 diagram scaled in the way I’ve been scaling them, a length of wings setting of 15 and a brush width of 2 works well. This can be paired with path lengths of 5.0 pixels and will do nicely.

Tampa under front, Tampa 2 zone defense. Modeled on the diagram in Matt Bowen’s Tampa 2 article.

Tom Landry’s 4-3 Inside, showing a 1960s era strong side rotating zone, an early Cover 3. SAM and left cornerback jam before falling into zone.

Drawing a zone drop.

Load your diagram. Add a new transparent layer. Make sure you’re drawing on the transparent layer. Use the rectangle select tool (letter “R”). Choose a region to highlight as a zone. At this point select the bucket fill tool (shift B) and then select the color for the bucket fill. Use a foreground fill and set the opacity to about 50%. If your field is light green, use a dark green to fill the zone.

If you have more than one zone to add, add them all now.

Once complete, select all (important) and add another layer. On this new layer, add a path from the middle of the zone to the player. Select Tools -> Arrow (you added the arrow plugin, didn’t you?). Adjust arrow length of wings and brush width and draw the arrow. Repeat as needed.

If the path isn’t straight or you need a bar to create a “jam”, just use the path tool as needed.

If you want to add text or label the diagram, I’d suggest adding another transparent layer and putting the text above the main, zones, and arrows.

Once done, save the file as a GIMP native file and then again as a JPEG file. The second save will cause an export, crunching all the layers down to one image.

Miami 43, shade front, man plus cover 1 by the free safety.

Drawing man to man coverage

The trick here is to use the path tool to make a stippled (dotted) image. Choose a path from the defender to the player to be defended. When you choose stroke path, choose a line type (there are many). I like the stippled pattern, as it’s unlikely to be mistaken for a solid line.