mapbox-gl/js/util/interpolate.js

A WebGL interactive maps library

'use strict';

module.exports = interpolate;

function interpolate(a, b, t) {
    return (a * (1 - t)) + (b * t);
}

interpolate.number = interpolate;

interpolate.vec2 = function(from, to, t) {
    return [
        interpolate(from[0], to[0], t),
        interpolate(from[1], to[1], t)
    ];
};

/*
 * Interpolate between two colors given as 4-element arrays.
 *
 * @param {Color} from
 * @param {Color} to
 * @param {number} t interpolation factor between 0 and 1
 * @returns {Color} interpolated color
 */
interpolate.color = function(from, to, t) {
    return [
        interpolate(from[0], to[0], t),
        interpolate(from[1], to[1], t),
        interpolate(from[2], to[2], t),
        interpolate(from[3], to[3], t)
    ];
};

interpolate.array = function(from, to, t) {
    return from.map(function(d, i) {
        return interpolate(d, to[i], t);
    });
};