﻿ PERGOLA JavaScript SVG Library – API Reference – Geometry # Geometry

This subset of geometry functions is particularly aimed at vector editing applications.

### pergola.geom

intersectionPoint(a1, a2, b1, b2)

Get intersection point between line a1,a2 and line b1,b2. The points are objects with x and y number properties. Returns {x : x, y : y} intersection point object, or false.

intersect(a1, a2, b1, b2)

Test intersection between line a1,a2 and line b1,b2. The points are objects with x and y properties. Returns true if lines intersect, or false.

pointBetween(a, b, c)

Test if point c is between point a and point b. Unidimensional (x or y). Returns true if point is between, or false.

pointOnLine(p, a, b)

Tests if point p is on segment a,b. The points are objects with x and y properties. Treats horizontal and vertical lines. Applies 1 x 10−6 compensation. Returns true if point is on line, or false.

getPDistance(x, y, x1, y1, x2, y2)

Get shortest distance from point x,y to line x1,y1 x2,y2. Returns shortest distance number.

getPPoint(p, l)

Get the perpendicular point on line l ({x1,y1,x2,y2}) from point p ({x,y}). Returns {x : x, y : y} perpendicular point object.

getP2Pdistance(a, b)

Get the distance between two points. a and b are objects with x and y properties. Returns distance number.

centroid(points, area)

Get true centroid of a polygon. points is an array whose elements are objects with x and y properties. area is the polygon's area. Returns {x : x, y : y} center point object.

crossProduct(v1, v2)

Vectors v1 and v2 are objects with x and y properties. Returns number.

### pergola.geom.angle

degrees(p1, p2)

Get rotation angle of line p1,p2. p1 and p2 are objects with x and y properties. Returns a number representing the angle in degrees.

radians(dy, dx)

Get angle in radians from center point, where dy is y - cy, and dx is x - cx. A typical use is when drawing a line or dragging one anchor point of a line. Returns a number representing the current angle in radians.

toDegrees(radians)

Converts radians to degrees. Returns degrees number.

toRadians(degrees)

Converts degrees to radians. Returns radians number.

angleBetween2Lines(a, b)

Get angle between two lines. a and b are objects ({x1,y1,x2,y2}). Returns a number representing the angle in degrees.

constrain(angle[, cardinals])

Constrain an angle to fixed values. if cardinals is not specified the value 16 (22.5 degrees) is used. A typical use is when drawing a line or dragging one anchor point of a line. Returns a number representing the constrained angle in degrees.

### pergola.geom.area

triangle(s)

Computes the area of a triangle, based on sides. s is an array containing the sides' length. Returns area number.

polygon(X, Y, n)

Computes the area of a polygon, based on vertices. X is an array of ordered x vertices; Y is an array of ordered y vertices; n is the number of sides. Returns area signed number (negative for clockwise order).