intercepts function doesn't work with perfectly-horizontal intercepting lines about bezierjs HOT 7 CLOSED

hi @harjis can you please file this as a new issue. Closed issues should remain closed, to keep single issues tied to single PRs.

from bezierjs.

Further investigation reveals that the problem is something to do with the fact that my line is a perfectly straight horizontal line. If I vary the y coordinate on either end of the line by even so much as 0.00000001, then the intercept is found. It's only when they're equal that the intercept fails.

from bezierjs.

hm, that sounds like somewhere the y delta being 0 is leading to bad stuff... division by zero perhaps. Good find!

from bezierjs.

No worries. Great library overall though, so thanks- it's saved me a tonne of time!

from bezierjs.

Vertical lines too.
But it works:

var vertical = {
    p1: { x: x, y: 0 },
    p2: { x: x + 1e-10, y: 1 },
};
bezier.intersects(vertical);

from bezierjs.

Hi!

First of all great work with the library! Has saved me a ton of time.

The issue I have is an intersection with cubic bezier curves and straight horizontal bezier curve. My code is as follows:

    const r = 150;
    const k = 0.55228;
    const circleArc = [
      { x: r * 2, y: r }, // Intersection point
      { x: r * 2, y: r + k * r },
      { x: r + k * r, y: r * 2 },
      { x: r, y: r * 2 }
    ];
    const straightLine = [
      { x: r, y: r },
      { x: r * 2, y: r }, //Intersection point
      { x: r * 2 + k * r, y: r },
      { x: r * 4, y: r }
    ];
    const circleArcBezier = new Bezier([...circleArc]);
    const straighLineBezier = new Bezier([...straightLine]);

    console.log(circleArcBezier.intersects(straighLineBezier)); // Empty array

To my understanding the lines should intersect each other at point { x: r * 2, y: r }. Also If I change the straight line even 1px the intersection is detected.

I'm not sure if this is the same issue as in #70 so I commented here.

Thanks again for your awesome work!

from bezierjs.

Oh yeah and this happens in Chrome Version 58.0.3029.110 (64-bit) and Firefox 53.0.3 (64-bit) at least with version 2.2.3

from bezierjs.