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pixi.js / lib / core / graphics / utils / bezierCurveTo.js
@Matt Karl Matt Karl on 16 Nov 2016 1 KB 4.2.1
"use strict";

exports.__esModule = true;
exports.default = bezierCurveTo;
/**
 * Calculate the points for a bezier curve and then draws it.
 *
 * Ignored from docs since it is not directly exposed.
 *
 * @ignore
 * @param {number} fromX - Starting point x
 * @param {number} fromY - Starting point y
 * @param {number} cpX - Control point x
 * @param {number} cpY - Control point y
 * @param {number} cpX2 - Second Control point x
 * @param {number} cpY2 - Second Control point y
 * @param {number} toX - Destination point x
 * @param {number} toY - Destination point y
 * @param {number[]} [path=[]] - Path array to push points into
 * @return {number[]} Array of points of the curve
 */
function bezierCurveTo(fromX, fromY, cpX, cpY, cpX2, cpY2, toX, toY) {
    var path = arguments.length > 8 && arguments[8] !== undefined ? arguments[8] : [];

    var n = 20;
    var dt = 0;
    var dt2 = 0;
    var dt3 = 0;
    var t2 = 0;
    var t3 = 0;

    path.push(fromX, fromY);

    for (var i = 1, j = 0; i <= n; ++i) {
        j = i / n;

        dt = 1 - j;
        dt2 = dt * dt;
        dt3 = dt2 * dt;

        t2 = j * j;
        t3 = t2 * j;

        path.push(dt3 * fromX + 3 * dt2 * j * cpX + 3 * dt * t2 * cpX2 + t3 * toX, dt3 * fromY + 3 * dt2 * j * cpY + 3 * dt * t2 * cpY2 + t3 * toY);
    }

    return path;
}
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