Designing Celtic knots with Knotter

Node and Edge Properties

You might quickly find that creating a beautiful pattern isn't all that easy. To enhance your first knots, Knotter provides a few useful settings, starting with the node and edge properties, which are located on the right side of the program window.

After selecting a node at the end or corner of a pattern, you can change its shape using Shape | Selected Nodes (Figure 3). Use other properties to control the Curve , Angle , and Distance of the pattern corner to the point.

Figure 3: Modify your pattern using node and edge properties.

Setting the edge properties is similar. Using Selected Edges , you can again set the Curve property. Type lets you modify the edge lines. You decide if you want the lines to touch or if Knotter should separate them.

In the Action History , Knotter lists each task action you've taken. This allows you to revert to a previous step and start from there again. Be careful, though: All the steps following the reverted one will be lost.

To support the design process, by default, the work area shows a grid that can help you design symmetrical patterns. You can hide the grid or adapt it your purposes through View | Dialogs | Configure Grid . The Configure Grid dialog then opens on the right in the Action History area.

You activate or deactivate the grid with the check box next to Enable Grid . With Size , you can set the size of the grid units. Because complex knot patterns can involve minute details, it's a good idea to change the grid pattern. Under Shape , you can find two different triangle grids to set as an alternative.

To enhance your pattern further, add a customized background with Background . This opens another dialog in the Action History area. Here you can add a background color or image.

Formats

Knotter stores its graphics in its own .knot format. Optionally, you can save the knot images as XML. To continue using the artwork, Knotter provides an export function under File | Export or Ctrl+E.

In the Export Image that opens, choose whether you want the knot pattern to be exported as a lossless, scalable vector graphic or in the PNG, JPG, or BMP raster format (Figure 4). Regardless, the export lets you set two significant parameters that can affect the outcome.

Figure 4: With the export function, you can save your designs as vector graphics or in a raster format such as PNG.

Using Include Graph in output , you can include the red points and blue lines that Knotter shows for creating patterns in the export. If you have a background graphic, using Include background image lets you export it as well.

Exporting as an SVG graphic requires no further settings. All it takes is clicking the Export SVG button and giving a storage location and filename. Because of a bug, you need to include the .svg filename extension or the export won't work. The same goes for raster graphics, where you need to add the appropriate filename extension.

A strange phenomenon occurred in openSUSE with Knotter version 0.9.5. Whereas Inkscape opened the save SVG file without a problem, Knotter aborted with the message Error while reading .

Exporting in raster graphic format allows some additional settings. First, it's advisable to set the Antialiasing option so that the export filter smooths the edges. In Background , you set the background for the knot pattern. If the background is transparent, be sure to choose a file format that supports transparency (i.e, PNG).

Finally, set the size of the exported image. You start the export with Export Image .