About Curves

The Curves tool allows you to draw, single and multiple Bézier curves, Freehand lines, Spline curves and clouds.

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Topics in this Section

• Bézier paths
• Splines
• Freehand Curves
• Revision Clouds

Bézier Curves

This method can be used to draw multiple, connected Bézier paths, parametric curves defined by two vertices and two tangent lines: 

• Click to set the first vertex, move the pointer and click to set the next vertex; double click to end the chain of Bezier curves.
• To draw a curve during construction, click and drag to define its profile.

The resulting path now can now be edited to smooth the vertices and turn the straight segments into the desired curves: this way the first tangent of the next curve is always defined by the previous one. Bézier curves have the Fill property: select the desired color on the “Fill color” menu of the Properties bar.

Edit a Bézier curve

• Hover the cursor over one vertex of the selected curve toshow the pop-up menu with the options to add or delete vertices and smooth or sharpen the path by creating connected curves or straight segments.
• By clicking on one of the four control points of a selected curve, you can change its position and visually adjust the profile. With multiple Bézier curves, by editing a definition point the connected tangents are constrained to keep the same angle: move the control points of the tangents to change the angle and adjust the shape of the curve. 
• Hold down the Alt key while moving the control points of the tangents to edit asymmetrically; Alt key + Cmd key to disconnect the tangents.

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The nodes of a bézier path can also be modified through the Object Info panel: select the node and change its coordinates and node type. The node types are:

• Straight: the node has no tangents and the curve is rendered as a straight line.
• Symmetric: the tangents extend by the same length and angle on both sides of the node.
• Asymmetric: the tangents are aligned at the same angle, but different length.
• Disconnected: the tangents are totally independent and each control point has its own angle and length.

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Clouds

Use this method to draw revision clouds and mark areas of the drawing that require special attention or further development.

The Revision Cloud method creates a composite shape made of arcs.

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Freehand Lines

The Freehand method lets you create spline curves by following the movement of the cursor. The algorithm transforms the movement of the cursor on screen to smooth curves.

The freehand method has two properties: smoothing factor, that defines the complexity of the curve, and the drawing option. You can adjust the smoothing factor of new paths through the Freehand settings window: 1 means that the path will preserve its original shape, but might have many vertices; 6 is the maximum smoothing and the path will be considerably simplified.

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On the same panel, you can also choose to draw freehand paths with a click-drag method instead of the standard click-click: this option is specially useful when used with a pen tablet, because it allows a more natural way of drawing.

Splines

A spline is a smooth curve that passes through a series of points. Splines in HighDesign are third-degree (cubic) polynomial segments, known as nonuniform rational B-Splines (NURBS).

Splines have a wide range of uses due to the simplicity of their construction, ease of editing and adaptability to mimic complex shapes.

Construct a Spline

To construct a spline, click to specify the start point, move the pointer and click to specify the next point. Double-click to end the curve or return to the start point to close the shape.

Press the X (cancel) button or the Esc key to cancel the last point.

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Editing a Spline

You can modify the profile of a spline by stretching a point, or by adding and removing vertices.

• Hover the cursor over one vertex of the selected curve to show the pop-up menu with the options to add or delete points;
• Move the given points of the selected curve with the Arrow tool or with the pointer and the Spline or Freehand tool method active. 

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