/**
* Computes the distance between two points
*
* @param {Point} p
* @param {Point} q
*
* @return {Number} distance
*/
export function pointDistance(a, b) {
if (!a || !b) {
return -1;
}
return Math.sqrt(
Math.pow(a.x - b.x, 2) +
Math.pow(a.y - b.y, 2)
);
}
/**
* Returns true if the point r is on the line between p and q
*
* @param {Point} p
* @param {Point} q
* @param {Point} r
* @param {Number} [accuracy=5] accuracy for points on line check (lower is better)
*
* @return {Boolean}
*/
export function pointsOnLine(p, q, r, accuracy) {
if (typeof accuracy === 'undefined') {
accuracy = 5;
}
if (!p || !q || !r) {
return false;
}
var val = (q.x - p.x) * (r.y - p.y) - (q.y - p.y) * (r.x - p.x),
dist = pointDistance(p, q);
// @see http://stackoverflow.com/a/907491/412190
return Math.abs(val / dist) <= accuracy;
}
var ALIGNED_THRESHOLD = 2;
/**
* Returns whether two points are in a horizontal or vertical line.
*
* @param {Point} a
* @param {Point} b
*
* @return {String|Boolean} returns false if the points are not
* aligned or 'h|v' if they are aligned
* horizontally / vertically.
*/
export function pointsAligned(a, b) {
if (Math.abs(a.x - b.x) <= ALIGNED_THRESHOLD) {
return 'v';
}
if (Math.abs(a.y - b.y) <= ALIGNED_THRESHOLD) {
return 'h';
}
return false;
}
/**
* Returns true if the point p is inside the rectangle rect
*
* @param {Point} p
* @param {Rect} rect
* @param {Number} tolerance
*
* @return {Boolean}
*/
export function pointInRect(p, rect, tolerance) {
tolerance = tolerance || 0;
return p.x > rect.x - tolerance &&
p.y > rect.y - tolerance &&
p.x < rect.x + rect.width + tolerance &&
p.y < rect.y + rect.height + tolerance;
}
/**
* Returns a point in the middle of points p and q
*
* @param {Point} p
* @param {Point} q
*
* @return {Point} middle point
*/
export function getMidPoint(p, q) {
return {
x: Math.round(p.x + ((q.x - p.x) / 2.0)),
y: Math.round(p.y + ((q.y - p.y) / 2.0))
};
}
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