Cardinal spline
===============
A `curve()` (cardinal spline) extension for HTML5 Canvas (JavaScript).
This library extends the 2D context with a new optimized `curve()` method
to enable drawing of cardinal splines - splines that goes through the defined
points.
The method is passed a simple array of points and a line is drawn through
them at given or default tension and segment resolution, open or closed loop.
*Not to be confused with Bezier splines which uses end points and one
or two control points, whereas the line is drawn somewhere between.
With a cardinal spline the smooth curve goes through every point
defined and you can have as many point as you wish in a single spline.*
Usage
-----
Make sure the script is loaded before a 2D context is retrieved from the
canvas element.
**Example**
ctx.moveTo(points[0], points[1]); // optionally move to first point
ctx.curve(points); // add cardinal spline to path
ctx.stroke(); // rasterize path
will draw the points in the array which is arranged in this manner:
[x1, y1, x2, y2, ... xn, yn]
Optionally a tension value can be given *(default: 0.5)*:
ctx.curve(points, 0.5); // set tension [0.0, 1.0] +/-
as well as a segment resolution value *(default: 20)*:
ctx.curve(points, 0.5, 20); // points in each segment
The curve can also be drawn closed. All arguments must be given in this
case *(default: false (open))*:
ctx.curve(points, 0.5, 20, true); // make a closed loop
The methods returns an array with the spline points which can be used for
tracking, calculate length and so forth:
var splinePoints = ctx.curve(points);
License
-------
Released under [MIT license](http://choosealicense.com/licenses/mit/). You can use this class in both commercial and non-commercial projects provided that full header (minified and developer versions) is included.
*© 2013-2014 Epistemex*
