A Bézier spline is a curve specified by four points: two end points (p1 and p2) and two control points (c1 and c2). The curve begins at p1 and ends at p2. The curve doesn't pass through the control points, but the control points act as magnets, pulling the curve in certain directions and influencing the way the curve bends. The following illustration shows a Bézier curve along with its endpoints and control points.
Note that the curve starts at p1 and moves toward the control point c1. The tangent line to the curve at p1 is the line drawn from p1 to c1. Also note that the tangent line at the endpoint p2 is the line drawn from c2 to p2.
To draw a Bézier spline
-
Choose the Graphics » Curve » Bezier command or click the
tool in the toolbar.
-
Specify the starting point.
-
Complete the line segment by specifying the end point. You can use the pointing device or you can open the dialog box for entering values. In the dialog box, the coordinates of the endpoint can be specified as follows:
By typing the point coordinates directly.
By specifying the offset from the starting point.
Specifying the inclination of the line relative to the horizontal axis and its length.
-
Specify the first control point.
-
Specify the second control point.
The line is created with the current pen style.
Commands and options
To start a new curve, press the SPACEBAR.
To close the tool without drawing the curve press ESC.
To remove the last inserted point, press BACKSPACE.
To specify the coordinates of the points or the value of the lengths you can use the pointing device or you can press INS to open the dialog box for entering values.