@jscad/modeling
Version:
Constructive Solid Geometry (CSG) Library for JSCAD
32 lines (30 loc) • 830 B
JavaScript
/**
* Get the X coordinate of a point with a certain Y coordinate, interpolated between two points.
* Interpolation is robust even if the points have the same Y coordinate
* @param {vec2} point1
* @param {vec2} point2
* @param {Number} y
* @return {Array} X and Y of interpolated point
* @alias module:modeling/maths/utils.interpolateBetween2DPointsForY
*/
const interpolateBetween2DPointsForY = (point1, point2, y) => {
let f1 = y - point1[1]
let f2 = point2[1] - point1[1]
if (f2 < 0) {
f1 = -f1
f2 = -f2
}
let t
if (f1 <= 0) {
t = 0.0
} else if (f1 >= f2) {
t = 1.0
} else if (f2 < 1e-10) { // FIXME Should this be EPS?
t = 0.5
} else {
t = f1 / f2
}
const result = point1[0] + t * (point2[0] - point1[0])
return result
}
module.exports = interpolateBetween2DPointsForY