Control point

As explained in How Computers Make Books

A control point is a point whose position determines how a Bézier curve deviates from the line between its endpoints.

A control point is an adjustable point that pulls a Bézier curve away from the straight line between its endpoints. A typical curve has two control points, one associated with each endpoint; moving them farther away increases the curve’s deviation. The curve may bend one way, two ways, or not at all. section 2.2

Shaping a letter

A designer can move control points interactively to build curved lines, then stitch several curves together into paths. An ampersand uses three such paths: one for its main shape and two for its holes. Aligning neighboring control points at 180° can make a join smooth. section 2.2

Figure 2.5 Several Bézier curves and their control points (shown as black dots)

Compare several Bézier curves and see how their black-dot control points change the curves’ shapes. section 2.2

How How Computers Make Books covers it

How deep it goes

Defines control points and their visual effect, then sketches smooth joins without developing the underlying mathematics.

Examples

Uses interactive curve editing, chained curves forming an ampersand, and control-point alignment for smooth joins.

What you can do after

Apply it via an interactive graphics program to adjust Bézier curves and create connected letterform paths.

How it connects

Connects control points to Bézier curves, endpoints, paths, and smooth curve joins.

liveBookmanning.com

Read How Computers Make Books on liveBook Get the book at manning.com

Also explained in

• 

  liveBookmanning.com
  Math for Web DesignA control point is a point that determines the shape and local behavior of a Bézier curve without necessarily lying on the curve.
• 

  liveBookmanning.com
  Advanced Algorithms and Data StructuresA control point is a point that determines the shape and direction of a Bézier curve without generally lying on the curve.
• 

  liveBookmanning.com
  Geometry for ProgrammersA control point is a point whose position influences the shape or position of a spline or other parametric geometric representation.

Compare how 4 books explain control point →

Related concepts

• Bézier curvepart of · A Bézier curve is a parametric curve whose shape is determined by control points through Bernstein basis functions.
• pointkind of · A point is a zero-dimensional location in a geometric or coordinate space represented by an ordered set of coordinate values.
• accelerationconfigures · Acceleration is the rate at which an object's velocity changes over time.
• tangent vectorconfigures · A tangent vector is a vector of first-order derivative values representing sensitivity or instantaneous direction under an input perturbation.
• cubic-bezier()part of · The CSS cubic-bezier() function defines a timing function using a cubic Bézier curve specified by two control points.
• NURBS modelused by · A NURBS model is a geometric representation of curves and surfaces using weighted control points, knot vectors, and non-uniform rational basis spline functions.

This explainer was generated by Manning's knowledge graph from the text of How Computers Make Books. The section links point to the parts of the book it draws on.