tagussan / bspline

A simple and fast uniform-knot BSpline curve implementation by javascript.

BSpline

A simple and fast uniform-knot BSpline curve implementation by javascript. Usually, BSpline's basis function is defined recursively by De Boor's algorithm. But this library includes pre-calculated uniform-knot BSpline basis. Thus, the library works very fast.

Usage:

var spline = new BSpline(points,degree,copy [optional]);
spline.calcAt(t);

• points : The array of points. Array of any dimensional vector is OK.
• degree : The degree of BSpline curve. degree should be 2,3,4 or 5.
• copy : This is optional. If this is omitted, BSpline uses the points itself. If true, BSpline copies points so that changes of points don't affect the curve.
• t : The parametor of BSpline. t is in [0,1]. If t = 0 then returns first point of points. If t = 1 then returns last point of points.

Example:

var points = [[1,2],[2,3],[3,4]];
var spline = new BSpline(points,3); //making BSpline
for(var t = 0;t<=1;t+=0.01){
    var p = spline.calcAt(t); 
    draw(p);
}

Demo is available here

For more information, please visit here

bspline's Issues

basisDeg4 calculation error

result when x is [-0.5,0.5) should equals to 25.0/64.0 - x1.0/8.0(3.0/4.0 + x*(5.0/2 + x))

Really hoped to find a plain implementation, too

I've spent two days on google trying to find even a single decent implementation of B-splines that isn't either hardcoded, or doesn't actually connect all the control points (starting the curve away from the first control point instead of at the first control point, and ending short, too).

then I found your code, but unfortunately instead of a generic implementation, it's also hardcoded only for a handful of orders... I know it's been 2 years, but would you consider adding the slower, generic "works for any order you need" function as well, that properly draw the connected curve from the first to the last control point? =(