Operation Manual

Stars
• 4-point star, 8-point star, 24-point star – use the dot to change the thickness and shape of
the star points.
• Vertical scroll, horizontal scroll – use the dot to change the width and shape of the scroll.
• Doorplate – use the dot to change the inward curvature of the corners.
Curves and polygons
Bézier curves
The editing of curves depends on the mathematics of Bézier curves
1
. Explaining Bézier curves
goes beyond this scope of this chapter. See Chapter 11 Advanced Draw Techniques for more
information on drawing and manipulating Bézier curves.
The editing of a Bézier curve consists in principle of moving points or tangents passing through
these points. Each tangent has one control point at each end and a junction point where it meets
the curve. The relative angle and distance between the control points determine the shape of the
curve. Figure 57 shows what happens starting from a basic circle and changing only one point on
the circle.
You can create many different shapes by moving either the junction point itself, or one or both of
the round handle points at either end of the tangent. Draw offers more possibilities when you use
the functions on the Edit Points toolbar.
Figure 57: Creating different shapes by changing the tangent
Converting to curve or polygon
Before modifying the points on an object, you must convert the object to a curve or a polygon,
depending on what kind of effect you want to produce.
After selecting an object, go to Modify > Convert on the main menu bar and select either To
Curve or To Polygon. Alternatively, right-click on an object and select Convert > To Curve or
Convert > To Polygon from the context menu.
After converting an object to a curve or polygon, click on the Points icon on the Drawing
toolbar and the Edit Points toolbar opens (Figure 58). You can also open this toolbar using View >
Toolbars > Edit Points on the main menu bar.
You will notice that after the conversion, the handles located in the corners of the selection
rectangle have disappeared. This behavior is normal because the handles used with the tools on
the Edit Points toolbar are located along the outline or trace of the object.
1 Bézier curves were invented by Pierre Bézier, an engineer working with the Renault car manufacturer,
who developed the technique in the 1960s. The technology was intended to make modeling the surface
of vehicles easier.
60 LibreOffice 4.3 Draw Guide