Chapter 1. Knotter User Guide

## Chapter 1. Knotter User Guide

## Introduction

Knotter is a highly configurable interlace designer.

Interlace patterns are a kind of design historically used as a decorations in many places and by different cultures, some examples are Celtic knotworks and Islamic interlaces.

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

Knotter aims to allow its user to design such patterns in an intuitive way and to provide easy ways to integrate the result in external general-purpose graphic software.

For this purpose, designs created within Knotter can be save in a custom human-readable format and exported as Scalable Vector Graphics and in a wide number of raster image formats.

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

## Command-line interface

See the Knotter man page

## 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 Nodes → Link (Ctrl+L) and Nodes → Unlink 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 lines turn back without crossing.

Wall

  The lines follow the edge without crossing.

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

| Tip
The type of an edge is changed with the mouse wheel or with the edge context menu.

### Quick graph design

Adding nodes and edges one at the time can be very tedious, Knotter provides the Tools → Edge list (Alt+Shift+L) tool to make this 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 rectangular 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 Nodes → Horizontal flip and Nodes → Vertical flip.

When several nodes are selected, they can be transformed (rotated and translated) by dragging the arrows that appear on the vertices of the bounding rectangle.

### 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 docks allow the configuration of display and shape options.

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.

Cusp Distance

  Distance between the graph node and cusp tip.

Curve Style

  Various cuspid shapes.

Point Style

  How the sharp points are rendered.

  Bevel

    Flat.

  Miter

    With a sharp point.

  Round

    Smooth.

| Tip
Some style settings can be configured on individual nodes, using the context menu (right click on a node) or with the "Selection Style" dialog

Solomon's knots and trefoils rendered using various styles.

Style settings docks.

## 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.

#### Mode

The export mode allows the selection of the rendiring style used in the exported image

Normal

  Use the default rendering, all style options are applied to the final result.

Simplified

  Export the interlace as a stroke sequence.

  For raster images the only noticeable difference with `Normal` is that the outline is not visible.

  In vector exports, the result will be a cleaner, un-extruded path that can be customized more easily.

  This is useful if you plan to edit the image with an external program as it will give more control on shape changes.

Loops

  Has a similar result as `Simplified` But all closed loops are colored differently.

#### Vector

Exports in the Scalable Vector Graphic format (SVG)

#### Raster

Antialias

  If checked, the output image will be supersampled.

Compression

  The compression level, the result depends on the exported format ( 0% will produce large, uncompressed files; 100% small files ).

  When exporting to a JPEG image, heavy compression will result in poor quality.

  This option in only meaningful for export format that support compression.

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.

Export dialog.

Knotter Manual |  | Chapter 2. Man pages