120 lines
2.5 KiB
JavaScript
120 lines
2.5 KiB
JavaScript
/**
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* Returns the length of a vector
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*
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* @param {Vector}
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* @return {Float}
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*/
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export function vectorLength(v) {
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return Math.sqrt(Math.pow(v.x, 2) + Math.pow(v.y, 2));
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}
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/**
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* Calculates the angle between a line a the yAxis
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*
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* @param {Array}
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* @return {Float}
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*/
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export function getAngle(line) {
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// return value is between 0, 180 and -180, -0
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// @janstuemmel: maybe replace return a/b with b/a
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return Math.atan((line[1].y - line[0].y) / (line[1].x - line[0].x));
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}
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/**
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* Rotates a vector by a given angle
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*
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* @param {Vector}
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* @param {Float} Angle in radians
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* @return {Vector}
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*/
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export function rotateVector(vector, angle) {
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return (!angle) ? vector : {
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x: Math.cos(angle) * vector.x - Math.sin(angle) * vector.y,
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y: Math.sin(angle) * vector.x + Math.cos(angle) * vector.y
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};
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}
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/**
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* Solves a 2D equation system
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* a + r*b = c, where a,b,c are 2D vectors
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*
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* @param {Vector}
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* @param {Vector}
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* @param {Vector}
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* @return {Float}
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*/
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function solveLambaSystem(a, b, c) {
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// the 2d system
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var system = [
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{ n: a[0] - c[0], lambda: b[0] },
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{ n: a[1] - c[1], lambda: b[1] }
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];
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// solve
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var n = system[0].n * b[0] + system[1].n * b[1],
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l = system[0].lambda * b[0] + system[1].lambda * b[1];
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return -n/l;
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}
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/**
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* Position of perpendicular foot
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*
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* @param {Point}
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* @param [ {Point}, {Point} ] line defined throug two points
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* @return {Point} the perpendicular foot position
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*/
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export function perpendicularFoot(point, line) {
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var a = line[0], b = line[1];
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// relative position of b from a
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var bd = { x: b.x - a.x, y: b.y - a.y };
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// solve equation system to the parametrized vectors param real value
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var r = solveLambaSystem([ a.x, a.y ], [ bd.x, bd.y ], [ point.x, point.y ]);
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return { x: a.x + r*bd.x, y: a.y + r*bd.y };
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}
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/**
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* Calculates the distance between a point and a line
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*
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* @param {Point}
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* @param [ {Point}, {Point} ] line defined throug two points
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* @return {Float} distance
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*/
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export function getDistancePointLine(point, line) {
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var pfPoint = perpendicularFoot(point, line);
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// distance vector
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var connectionVector = {
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x: pfPoint.x - point.x,
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y: pfPoint.y - point.y
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};
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return vectorLength(connectionVector);
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}
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/**
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* Calculates the distance between two points
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*
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* @param {Point}
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* @param {Point}
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* @return {Float} distance
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*/
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export function getDistancePointPoint(point1, point2) {
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return vectorLength({
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x: point1.x - point2.x,
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y: point1.y - point2.y
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});
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} |