14.26. Spyrogimp

14.26.1. Wirkungsweise

Abbildung 17.377. Anwendungsbeispiel für das Filter Spyrogimp

Anwendungsbeispiel für das Filter Spyrogimp

Filter Spyrogimp angewandt


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.

14.26.2. Filteraufruf

This filter is found in the image window menu under FiltersRenderSpyrogimp….

14.26.3. 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 settings for gimp tools. These settings can be changed while the plugin is running.

[Anmerkung] Anmerkung

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

14.26.3.1. 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.

14.26.3.2. Tool Settings

Spyrogimp uses gimp tools to perform the drawing. All the settings with which the drawings are done are taken from the chosen tool. For example, if you choose to use the Pencil tool (by choosing it from the Tool menu)then all the settings of the Gimp Pencil 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.

14.26.3.3. Gradient Settings

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

14.26.4. Eigenschaften

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

Abbildung 17.378. Eigenschaften für das Filter Spyrogimp

Eigenschaften für das Filter Spyrogimp

[Anmerkung] Anmerkung

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.

14.26.4.1. 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 - that move on the x and y axis - it does not use the fixed ring at all, and thus is not affected by changing it.

Werkzeug

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.

14.26.4.2. Curve Pattern Tab

Abbildung 17.379. Spyrogimp filter options (Curve Pattern)

Spyrogimp filter options (Curve Pattern)

The inner Toy Kit tab is shown on the right.


Specify pattern using either the Gears or Toy Kit tabs. The pattern is specified only by 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, however, these are menus which 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.

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.

14.26.4.3. Fixed Gear Tab

Abbildung 17.380. Spyrogimp filter options (Fixed Gear)

Spyrogimp filter options (Fixed Gear)

Form

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.

  • 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.

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.

14.26.4.4. Size Tab

Abbildung 17.381. Spyrogimp filter options (Size)

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.

14.26.4.5. 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 effect the pattern), press this to preview how the pattern looks.

Rücksetzen

Resets the dialog to its default options.

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 to not keep the layer, is that by using specific paint application modes, redrawing the pattern on the active layer can interact with it in interesting ways, that produce a different pattern had it been drawn on a new layer.