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A Lute Rose

This example illustrates how to use symmetric shapes and patterns. The aim is to design the lute rose (the decorative cover of a lute's sound hole) shown in Figure 11.139. This example uses a radial grid. All co-ordinates (R:A) are radial co-ordinates where R is the radius (bp) and A is the angle (degrees).

  1. Set the paper size to A3 landscape using the Settings->Paper menu.

  2. Use Settings->Grid->Grid Settings to select a radial grid with 100bp major division interval, 10 sub-divisions and 32 spokes. (See Figure 11.126.)

    Figure 11.126: Selecting a Radial Grid

  3. Create a path (using the open curve tool and the edit path tool) starting at (20:-170) containing three Bézier segments with control points:
    1. (145:-145), (215:-145), (200:-170)
    2. (200:135), (200:-115), (200:170)
    3. (210:150), (255:115), (200:100)
    (See Figure 11.127)

    Although the co-ordinates are being specified as radial co-ordinates, they are always stored as rectangular co-ordinates. This conversion may cause slight rounding errors.

    Figure 11.127: The Underlying Path

  4. In edit path mode, use the popup menu and select Has Symmetry (see Figure 11.128).

    Figure 11.128: Give the Path Symmetry Using the Popup Menu
    Using the edit path popup menu again, deselect Anchor Join (see Figure 11.129).

    Figure 11.129: De-anchoring the End Control Using the Popup Menu

  5. Still in edit path mode, move the control points governing the line of symmetry (coloured blue by default) to (85:-90) and (215:90) (see Figure 11.130).

    Figure 11.130: Move the Line of Symmetry
    Select the last control point on the path (not including the line of symmetry) and select the edit path popup menu item Convert To Curve. This should add a curve segment that joins the underlying path with its reflection (see Figure 11.131). Note that this joining segment only has one curvature control to enforce symmetry.

    Figure 11.131: Add a Joining Curve Between the Underlying Path and its Reflection

  6. Move the curvature control point on the join segment to (200:0) (see Figure 11.132).

    Figure 11.132: Adjust the Curvature Control of the Join Segment

  7. Leave edit path mode and, ensuring the path is still selected, use the Edit->Path->Line Styles->All Styles menu item to change the path style to: 10bp pen width, round cap and round join (see Figure 11.133).

    Figure 11.133: Change the Path Style

  8. The path should now look like that shown in Figure 11.134.

    Figure 11.134: The Symmetric Path

  9. Ensure that the path is selected. Use the Transform->Pattern->Set Pattern menu item. This should open the dialog box shown in Figure 11.135. Set the number of replicas to 11. Select the Rotational tab, and set the angle of rotation to 30 degrees.

    Figure 11.135: Setting the Pattern

  10. The shape should now look like that shown in Figure 11.136.

    Figure 11.136: The Pattern
    Switch to edit path mode. You should now see an extra control point (coloured green by default). Move this control to (0:0) (see Figure 11.137).

    Figure 11.137: Move the Control Governing the Rotational Anchor

  11. Leave path edit mode, select the ellipse tool and draw a circle around the pattern (see Figure 11.138).

    Figure 11.138: Add a Circle Around the Pattern
    Select the circle, set its fill colour to black and move the circle to the back of the stack. Select the pattern, and set its line colour to white. The image should now look as Figure 11.139.

    Figure 11.139: The Completed Lute Rose

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