OpenOffice.org OpenOffice - 3.3 Guía de usuario descargar pdf (Pagina 49)

The mouse pointer changes shape when hovered over a yellow handle. If you drag

one of these handles, you can modify the shape of the object; the type of change is

dependent on the shape itself. For example, you can round the corners of a rectangle

or square, change the angles of an arc or ellipse, or alter the control points of a

circular or elliptical segment.

How curves work

The editing of curves depends on the mathematics of Bézier curves

. The complete

study of such curves goes beyond this scope of this guide, and only the basics are

covered here. Chapter 10 (Advanced Draw Techniques) provides 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 two control points—one 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 51 shows

several variations 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.

Figure 51: Creating different shapes by changing the tangent

Draw offers even more possibilities when you use the functions on the Bézier curve

Edit Points toolbar.

The Edit Points toolbar

When you work in Edit Points mode, use the Edit Points toolbar, shown in Figure 52.

To activate this toolbar, choose View > Toolbars > Edit Points. It will then appear

whenever you select a curve and the Edit Points icon on the Drawing toolbar is

active.

On this toolbar, icons may be active or inactive depending on the selected object and

object point. With the Convert to Curve icon, you can determine for individual points

whether their connection will be made with straight lines or with curves.

Only with curves are the icons for tangents activated. An object that contains no

curves is treated as a polygon.

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.

Chapter 3 Working with Objects and Object Points 49

1 2 ... 44 45 46 47 48 49 50 51 52 53 54 ... 205 206

Sin comentarios

OpenOffice.org OpenOffice - 3.3 Guía de usuario Pagina 49