14.24. Spyrogimp
| 14. Rendering Filters |

### 14.24. Spyrogimp

#### 14.24.1. Overview

Figure 17.382. Example for the “Spyrogimp” filter

“Spyrogimp” applied

This filter draws Spirographs, Epitrochoids, and Lissajous curves. Immediate feedback is provided, by drawing to a temporary layer.

It reproduces curves drawn by Spirograph© toys. Here is an example from Wikipedia showing what gears and holes are:

Moving gear is inside fixed gear and only one hole is used.

#### 14.24.2. Activating the filter

This filter is found in the menu under Filters → Render → Spyrogimp….

#### 14.24.3. Selection and Tool

Much of the behavior of the plugin is determined by options set outside of the plugin, such as the current selection, or the settings of GIMP's tools. These settings can be changed while the plugin is running.

| Note
In contrast to options within the plugin, changing the current selection or tool settings will not redraw the pattern. To show the changes, click the Redraw button at the bottom of the plugin.

##### 14.24.3.1. The Current Selection

As in most plugins, the current selection determines the area where the pattern will be rendered. Typically, this would be a rectangular selection. There is however, an additional way the selection can be used.

The selection can be used as the shape of the fixed gear (under the Fixed Gear tab). The plugin will attempt to extract shapes from the selection, and draw a pattern inside of each shape. This is more interesting if you select a non-rectangular selection.

To have the pattern hug the boundaries of the shapes, use hole percent=100.

##### 14.24.3.2. Tool Settings

Spyrogimp uses GIMP's tools to perform the drawing. All the settings with which the drawings are done are taken from the chosen tool. For example, if you want to use the Pencil tool (by choosing it from the Tool menu), then all the settings of this tool will be used for drawing. You can change any of the tool settings while the plugin is running, and press the Redraw button to see how the pattern looks.

##### 14.24.3.3. Gradient Settings

When using the long gradient mode, some settings from the gradient tool are used.

#### 14.24.4. Options

Most of the options are organized under three tabs: Curve Pattern, Fixed Gear, and Size.

Figure 17.383. “Spyrogimp” options

| Note
This filter has been totally reimplemented since GIMP 2.10.10. If you are using an older version of GIMP, your dialog will look different.

##### 14.24.4.1. Options Above the Tabs

Curve Type

  The available curve types are: Spyrograph, Epitrochoid, Sine, and Lissajous. These correspond to physical models for drawing them, using either gears or springs. Spyrograph and Epitrochoid curves are obtained by using two gears - a fixed gear, and a moving gear. A Spyrograph pattern is obtained when the moving gear is rotated inside the fixed gear. When the moving gear is outside the fixed gear, an Epitrochoid pattern is generated. The Sine curve uses the fixed gear, but instead of a moving gear, there is a spring that moves perpendicular to the fixed gear's edge. The Lissajous curve is generated by two springs, which move on the x and y axis. It does not use the fixed ring at all, and thus is not affected by changing it.

  Figure 17.384. “Spyrogimp” Curve Types

  Curve types from left to right: Spyrograph, Epitrochoid, Sine and Lissajous.

Tool

  The GIMP tool with which to draw the pattern. The first tool is named Preview and its purpose is to draw quickly, rather than beautifully - so the pattern can be previewed. The other available tools are: PaintBrush, Pencil, AirBrush, Stroke, Ink, and MyPaintBrush.

Long Gradient

  When unchecked, the current tool settings will be used - this can either produce a gradient or not, depending on the tool settings. When checked, the plugin will produce a long gradient to match the length of the pattern, based on the current gradient, the "Reverse" setting, and the Repeat mode from the gradient tool settings. Setting the Repeat mode to Triangle Wave will produce a pattern that changes continuously, with no abrupt breaks. This is done by using the gradient followed by its reverse. Any other Repeat mode will simply use the gradient from start to finish.

  Figure 17.385. “Spyrogimp” Long Gradient Examples

  The left image, without Long Gradient, used the paintbrush tool with a gradient. The two right images were generated with the same gradient, but with Long Gradient checked. The right image used the Triangle Wave Repeat mode.

##### 14.24.4.2. Curve Pattern Tab

Figure 17.386. “Spyrogimp” filter options (Curve Pattern)

The inner Toy Kit tab is shown on the right.

Specify a pattern using the Gears, Toy Kit or Visual tabs. The pattern is based only on the settings of the active tab. Toy Kit is similar to Gears, but it uses gears and hole numbers which are found in toy kits. If you follow the instructions from the toy kit manuals, you should obtain similar results.

Fixed Gear Teeth

  Number of teeth of fixed gear. The size of the fixed gear is proportional to the number of teeth.

Moving Gear Teeth

  Number of teeth of moving gear. The size of the moving gear is proportional to the number of teeth.

Hole percent

  How far is the hole from the center of the moving gear. 100% means that the hole is at the gear's edge.

The Toy Kit tab also has Fixed Gear Teeth and Moving Gear Teeth options. In this case, however, they are limited to gear sizes that are provided with toy kits for drawing Spyrographs.

Hole Number

  Hole #1 is at the edge of the gear. The maximum hole number is near the center. The maximum hole number is different for each gear.

Figure 17.387. “Spyrogimp” Toy Kit Examples

The Toy Kit helps recreate designs from the toy kit. The left image uses a 105 fixed gear, and a 30 (blue), 45 (green) and 60 (red) moving gears, where each moving gear was used several times with Hole Number varying from 3 to 7. The right image also uses the 105 fixed ring, with moving ring 24 (Hole Number 4), and moving ring 80 (Hole numbers 16, 18, 20).

Figure 17.388. “Spyrogimp” filter options (Curve Pattern)

The Visual tab is shown in the middle on the right side.

The Visual tab creates more rounded, flower petal like patterns. It has the following settings:

Flower Petals

  The number of flower petals to draw.

Petal Skip

  The number of petals to skip.

Hole radius (%)

  The size of the hole.

Width (%)

  The width of the drawing.

Below the tabs there is an additional option.

Rotation

  Rotation of the pattern, in degrees. The starting position of the moving gear in the fixed gear. Note that this also changes the pattern when drawing Lissajous curves.

##### 14.24.4.3. Fixed Gear Tab

Figure 17.389. “Spyrogimp” filter options (Fixed Gear)

Shape

  The shape of the fixed gear to be used inside current selection.

  - Circle

  - Rack is a long round-edged shape provided in the toy kits.

  - Frame hugs the boundaries of the rectangular selection, use hole=100 in Gear notation to touch boundary. To generate a narrow frame width, use a small number of teeth for the moving gear.

  - Selection will hug boundaries of current selection - try something non-rectangular.

  - Polygon-Star morphs from an n-sided polygon (morph=0) to an n-sided star (morph=0.3) to a crazy flower (morph=1).

  - Sine with morph=0, it is just like a circle, but becomes more wavy as morph increases.

  - Bumps morphs from a polygon (morph=0) to a scalloped circle.

  Figure 17.390. “Spyrogimp” Shape Examples

  From left to right, Circle, Rack, Frame, and Selection shapes of the fixed gear. The selection in the right image was generated by selecting a large letter "T" that was produced by the text tool.

  Figure 17.391. “Spyrogimp” Polygon-Star Shape Examples

  From left to right, Morph = 0, 0.3, 0.6, 1

  Figure 17.392. “Spyrogimp” Sine Shape Examples

  From left to right, Morph = 0.1, 0.3, 0.5

  Figure 17.393. “Spyrogimp” Bumps Shape Examples

  From left to right, Morph = 0, 0.5, 1

Sides

  Number of sides of the shape. This applies only to the Polygon-Star, Sine, and Bumps shapes. Otherwise this option is disabled.

Morph

  Morph fixed gear shape. This applies only to the Polygon-Star, Sine, and Bumps shapes. Otherwise this option is disabled

Rotation

  Rotation of the fixed gear, in degrees.

##### 14.24.4.4. Size Tab

Figure 17.394. “Spyrogimp” filter options (Size)

Margin (px)

  Margin from the edge of selection. This controls the size of the pattern.

Make width and height equal

  When unchecked, the pattern will fill the current image or selection. When checked, the pattern will have same width and height, and will be centered. The difference between checked and unchecked will only be noticed if the size of the width and height of the selection differ.

##### 14.24.4.5. Buttons Below the Tabs

Redraw

  If you change the settings of a tool, change color, or change the selection (i.e., any settings outside of the plugin that affect the pattern), press this to update the preview to see how the pattern looks.

Reset

  Resets the dialog to its default settings.

Cancel

  Delete the temporary layer, and exit the plugin.

OK

  Render pattern to image. If Keep Layer is unchecked, this might take some extra time to complete, as the pattern needs to be redrawn on the active layer.

Keep Layer

  Determines what will happen to the temporary layer once OK is pressed. If checked, then once OK is pressed, the temporary layer is kept, and the plugin exits quickly. If unchecked, the layer is deleted, and the pattern is redrawn on the active layer.

  One reason not to keep the layer, is that by using specific paint modes, redrawing the pattern on the active layer can give interesting results. This can produce a different pattern than when it been drawn on a new layer.

14.23. Qbist |  | 14.25. Circuit

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