Anatomy of a path

Anatomy of a path

Paths and shapes (such as rectangles and ellipses) always consist of a sequence of curved and straight segments. Microsoft Expression Design offers two different types of paths: Bezier curves and B-spline curves.

  • Bezier curves   Pronounced "beh-zee-ay." A path created by a combination of points along the path (also named nodes) and control handles. Each anchor point can be a corner or a curve point, and each control handle describes the line's tangent at the anchor point. Most drawing applications use only Bezier curves to define paths.

    A path made completely of Bezier curves. Note the point (1) and control handle (2).

  • B-spline curves   A path using a series of anchor points that usually lie off the path itself. Each anchor point defines the general direction that the curve should travel. While this sounds more complex, B-spline curves are typically easier to control, produce smoother curves, and are easier to master. B-spline curves are widely used in 3D modeling software. Anchor points on a B-spline curve can also be either curve or corner points (the curve always travels through a corner point).

    A path made completely of B-spline curves


Paths are usually built completely from one type of curve or the other, but you can also mix the two curve types together by joining or appending two paths, or by using the Convert Anchor Point tool.

A B-spline path with a brush stroke applied to it


Closed paths

Paths can be open-ended (such as a simple line) or closed (such as rectangles or circles). You can close an open path, join two open paths together, or split a closed path so that it becomes open. When you fill an open path or use it as a clipping mask in a clipping mask group, Expression Design uses an imaginary (and invisible) straight line from the path's starting and ending points to create the fill area.

You can also build a path from multiple subpaths. For more information about this kind of path, see Create compound paths.

Path direction

Each path has a starting and an ending point, although these two might be the same point in a closed path. The end anchor point is marked with a small arrowhead Cc294864.d97cf8ff-e81d-4c06-bee9-ddc996f4f2aa(en-us,Expression.40).gif when you select the object. When you use a stroke to create a path, Expression Design applies the stroke in the direction of the path. You can reverse the path direction, or, for closed paths, change the starting point.

Creating paths

Expression Design has four different path-drawing tools:

  • Paintbrush tool

  • Pen tool

  • Polyline tool

  • B-Spline tool

You can also use these tools to quickly create predefined shapes:

  • Rectangle tool

  • Ellipse tool

  • Polygon tool (for stars and polygons)

  • Line tool

You can also create paths in the shape of text characters. For more information, see Convert text to path.

Send feedback about this topic to Microsoft. © 2011 Microsoft Corporation. All rights reserved.

Community Additions

© 2015 Microsoft