Knotter User Guide

Introduction

Interlace patterns are a kind of design hystorically used as a decorations in many places and by different cultures.

Knotter uses graphs to represent knots.

A good description of the algorithm used to render them and design tips can be found at Celtic Knotwork: the Ultimate Tutorial

An illumination on the cover of the Quran with an interlaced frame

Editing

A knot is produced from a graph where the edges define interactions between two knot lines.

Adding nodes

Double clicking on an empty spot on the drawing area will add a node. If you double click on an edge, the new node will split that edge in two.

Adding edges

To toggle edges between nodes, the Link selected and Unlink selected commands.

Changing edge type

Knotter supports three types of edge:

• Default - The two lines cross at the edge midpoint, one on top of the other
• Inverted - Like default but with the other line on top
• Hole - The line turn back without crossing
• Wall - The lines follow the edge without crossing

From left to right: Default, Inverted, Hole, Wall

The type of an edge is changed with the mouse wheel.

Quick graph design

Adding nodes and edges one at the time can be very tedious, knotter provides the Edge list tool to make the process easier.

When this is enabled, a single click will create a node and each new node is connected to the previous one by an edge.

To break the edge chain, click with the right button, you'll be able to start a new chain from the next node.

Selection and transformation

Only nodes can be selected and moved, the edges will follow their vertices.

A single node is selected by left clicking it, multiple nodes can be selected by holding Shift or Control.

Dragging the mouse from an empty spot will select the nodes within a rectangual area.

Dragging one of the selected nodes will move the selection, while moving nodes can be transformed using the mouse wheel (will scale the selection) or Shift + mouse wheel (will rotate the selection around the node under the cursor). These transformations are available when pasting nodes.

Selected nodes can be mirrored using the horizontal and vertical flip commands.

Snapping

To allow precise designs knotter offers a grid that, when enabled, will snap nodes to the closest point.

There are three types of grid: * Square - A regular square grid. * Triangular1 - A grid where the elements are equilateral triangles with a horizontal base. * Triangular2 - A grid where the elements are equilateral triangles with a vertical side.

The grid allows precise editing

Style

The Knot Style dialog allows the configuration of display and shape options. Changes are visible in the preview area of the dialog.

• Curve Control Point Distance - How much the knot line follows its direction when exiting from an edge.
• Crossing Gap - Distance between the end points when a lines are crossing.
• Minimum Cusp Angle - Minimum angle between two edge to make the knot line display a cuspid rather than a smooth curve.
• Curve Style - Various cuspid shapes
• Point Style - How the sharp points are rendered
  • Bevel - Flat
  • Miter - with a sharp point
  • Round - Smooth

Curve shapes avaliable in knotter

Style settings dialog

Some style settings can be configured on individual nodes, using the contect menu (right click on a node)

Save and Load

Knotter can save and load knots in its own human-readable format.

Export

The Export dialog gives many options to export the knot as Image

Vector

• Only shape - Only export the shape of the knot as a thin line, discarding any other style option

Raster

• Antialias - If checked, the output image will be supersampled.
• Compression - The compression level, the result depends on the exported format.
  • 0% = Large files
  • 100% = Small files
• Width/Height - The resulting image size, if they are different from the actual knot it will be scaled to fit those.
• Keep Ratio - When enabled, editing Width/Height will preserve their ratio.
• Reset Size - Change Width and Height back to the default.