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Old 09-03-2006, 08:13 PM
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Shapes 2: Shapes Bézier Path Tools in Corel Painter

Shapes 2: Shapes Bézier Path Tools in Corel Painter

Painter's Shapes make use of Bézier curves—mathematical formulae that efficiently encapsulate a wide range of curvilinear objects. Bézier curves are the digital equivalent to the engineering draftsman's french curves. And speaking of France, it was the French automobile engineer Pierre Bézier that developed these curves for use in the Renault CAD/CAM automobile design system. Bézier curves have become the basis for vector-based drawing applications, such as Corel Draw and Adobe Illustrator. The good news is that you don't need a degree in advanced mathematics to take advantage of Bézier curves—they are a completely visual curve creation tool.


Bézier Curve Terminology

The visual components of Bézier curves are remarkably simple. A Bézier curve is comprised of anchor points connected by line segments. In its simplest form this can be a straight line. When the path is a curve, wings extend from the anchor points. The wings have control handles on them. By dragging the wing's control handle, the curvature of the associated segment is adjusted. A line segment can be dragged and adjusted, as well. Line segments change in real-time as adjustments are made, making it very easy to arrive at the intended result. Both straight and curved segments can be used within a single line. A series of anchor points can be used to describe an amazingly complex line.

A path is either open or closed. An open path describes a line; a closed path describes a shape. Open paths have endpoints; closed paths do not.

Anchor points can be either smooth or corner points. A smooth anchor point allows the adjustment of the line segments on both sides of the anchor point by dragging its control handle. A corner point allows independent adjustment of the wing control handles.


Shapes Bézier Curve Adjustments

The Pen tool is the primary Bézier curve creation tool. Straight lines are created by simply clicking on the image. A Shapes layer is automatically generated. Clicking a series of points will result in a faceted line/shape. Clicking and dragging will create a smooth point with wings. An existing open path is added to by positioning the Pen tool over an endpoint. The cursor changes to the Resume at Endpoint cursor. Clicking the endpoint adds to the existing open path.

An open path is closed by positioning the Pen tool cursor over the initial endpoint. The cursor changes to the Join Endpoints cursor. Clicking on the endpoint closes the path.

The Shapes Direct Selection tool is the primary anchor point selection tool. Its cursor appears as a hollow arrow. This tool is accessed from either the Tool menu or by holding down the CTRL/CMD key when using any of the Shapes Editing tools.

When the Shapes Direct Selection tool is active, holding down the CTRL/CMD key will toggle the cursor to the Shapes Selection tool. Its cursor appears as a filled arrow. Click and drag on any portion of a Shapes element to move the entire element.

A single anchor point is selected by clicking on it with the Shapes Direct Selection tool. Multiple anchor points are selected by clicking and dragging a selection rectangle around the points with the Shapes Direct Selection tool.

A selected anchor point displays its wings. The Shapes Direct Selection tool is used to reposition the points, as well as adjust the orientation of the wings. By default, each wing's length is independently adjusted. Hold down the Shift key to linearly adjust both wings.

The Convert Point tool converts a smooth point to a corner point and vice versa. A point is converted with the the Convert Point tool by positioning the cursor over the wing control point of an active anchor point and dragging the control point. The anchor point is converted. Further adjustment of the wings is performed with the Shapes Direct Selection tool.

Besides adjusting wing control points, the Shapes Direct Selection tool is used to move anchor points. Doing so changes the geometry of the Shape. Alternatively, Bézier path segments are directly manipulated by clicking and dragging the curve segment.

It takes a bit of practice to become facile with Bézier curve creation and editing. Wing control points can get looped. Curve segments can spring out into unexpected shapes. Your control will develop through usage of the Shapes curve adjustment tools.


Shapes Bézier Curve Editing Tools

These tools are used for radical surgery to existing Bézier shapes. The Scissors tool is used to split an open path or convert a closed path to an open path. Use the Direct Selection tool to first choose the path segment to be split. Select the Scissors tool and click on the desired point of the active path to split the segment. A new anchor point appears at the split point. Use the Direct Selection tool to click and drag the point. The line segment separates from the former single path. The new endpoints will have wings for adjustment.

The Add Point tool is used to add points to an existing open or closed Bézier path. Use the Direct Selection tool to first choose a path segment to add points to. Select the Add Point tool and click on the desired location on the path segment to add a point. A new anchor point appears on the path. Use the Direct Selection tool to adjust the point.

The Delete Point tool is used to delete points from an existing open or closed Bézier path. Use the Direct Selection tool to first choose a path segment to delete points from. Select the Delete Point tool and click on the desired existing anchor on the path segment to delete it. The anchor point is deleted from the path. The anchor points formerly on either side of the deleted point now create a path segment.


Shapes Freehand Bézier Quick Curve Tool

There are times when a more spontaneous Bézier path is desirable. The Bézier Quick Curve tool is useful in these situations. The Quick Curve tool is used similarly to other Painter brushes except that it results in a single weight Bézier open or closed path (depending on whether you connect the endpoints). As with all Bézier paths, line weight can be uniformly adjusted via the Shapes Attributes dialog after the fact. When drawing with the Quick Curve tool, a dotted line preview visualizes the path. When the path is completed (by lifting your stylus), the preview path converts into a Bézier path with anchor points.


Shapes Bézier Oval and Rectangle Tools

These tools are used to create the universally functional oval and rectangular shapes. By default, both tools create unconstrained ovals and rectangles. Perfect circles and squares are created by holding down the Shift key before clicking and dragging the cursor. Both ovals and rectangles contain adjustable anchor points.


Shapes, Selections, and Layer Conversions

Shapes are capable of being converted into both layers and selections. In fact, these three Painter constructs are highly transmutable: selections can be converted into Shapes and layers; layers can be converted into selections; selections can be converted into Shapes and layers (by constraining a selection fill on an existing layer). This interplay opens up many possibilities.

Shapes can be converted into either a layer or selection via the Shapes menu, the Shapes Tools Property Bars, or the Shapes Tools Contextual Menu.

Selections can be converted into Shapes via the Select menu, the Selection Tools Property Bars, or the Selection Tools Contextual Menu.

Layers can be converted into selections via the Select menu > Auto or Color Select commands or the Layer palette Contextual Menu.


Fun To Follow!

We are now finished with examining Painter's Shapes organization, tools, and adjustments. In the next installment, we'll take our Shapes knowledge and apply it. There are indeed some surprising ways to utilize Shapes into your workflow...or to just have fun!

Viva la Painter!

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