Drawing Bézier curves
A Bézier curve is a smooth curved line (a spline)
that passes through two or more points. A Bézier curves is defined by
two anchor points — the curve's end points — and two external control
points, called handles. The handles are placed automatically when the
control points are drawn. You modify the shape of the curve by moving
(dragging) the handles. In EngView, a handy
use of the Bézier curves is for tracing of image contours.
Notes
- When you are drawing a series of connected
Bézier curves — for example, to construct a figure rather than a single
curve — the second point of a Bézier curve becomes the first point
of the next one. When you drag the pointer over the control points
of the objects, the control points are highlighted; you can start
drawing the next geometric object from such a point.
- An internal anchor point lies on the imaginary
line segment that connects its two handles. When you drag any of the
handles of an internal anchor point, the anchor point does not change
its position; the shapes of the two curves (connected by the anchor
point) are modified and the opposite handle moves so that the two
handles and the anchor point always lie on one axis.
- During repositioning a Bézier curve, when in
the contextual edit bar you enter a value in one of the edit boxes
Dx or Dy and then move to the next edit box, EngView limits
the scope of the Bézier curve preview according to the specified value.
Consider the following example:
If while repositioning a Bézier curve by dragging,
you enter a value of 40 mm for a relative Dx offset distance and
then move to Dy, when you point to where you want the Bézier curve
to be, Package Designer restricts the movement of the pointer beyond the
imaginary vertical borderline that stretches at 40 mm rightward from the
original Ox coordinate value of the Bézier curve. To drag the Bézier curve
preview freely, in the respective edit box (Dx or Dy) enter
0.00, and then press TAB or ENTER to move to the next edit box.
The zero-value rule is valid only for distance values.