org.nfrac.cljbox2d.vec2d — org.nfrac/cljbox2d 0.5.0

2D geometric point and vector helpers. All in terms of clojure vectors [x y]. Uses float precision for consistency with JBox2d.

abs clj

(abs x)

Absolute value; avoids reflection from overloaded Math/abs

angle-intersection clj

(angle-intersection xy0 ang0 xy1 ang1)

Point of intersection of two lines in the plane.

angle-left? clj

(angle-left? angle)

angle-to-gradient clj

(angle-to-gradient ang)

angle-up? clj

(angle-up? angle)

horizontal-angle? clj

(horizontal-angle? ang)

(horizontal-angle? ang tol)

Is angle horizontal, within +/- 1.5 degrees by default.

in-pi-pi clj

(in-pi-pi angle)

Returns the angle expressed in the range -pi to pi.

interior-angle clj

(interior-angle [v0 v1 v2])

Interior angle of a triple of points using law of cosines: cosC = (a^2 + b^2 - c^2) / (2ab) where, in a triangle, angle C is opposite side c.

line-intersection clj

(line-intersection [x0 y0] m0 [x1 y1] m1)

Point of intersection of two lines in the plane. First line passes through [x0 y0] with gradient m0. Other line passes through [x1 y1] with gradient m1. Gradient can be passed as nil for vertical lines.

PI clj

Pi (180 degrees).

PI_2 clj

Pi/2 (90 degrees).

polar-xy clj

(polar-xy mag angle)

Convert polar coordinates (magnitude, angle) to cartesian coordinates (x, y).

poly-edge-point clj

(poly-edge-point vv angle origin-pt)

Finds point on edge of a convex polygon shape (given by counter-clockwise vertices) at a given angle from origin-pt.

poly-flip-x clj

(poly-flip-x vv)

(poly-flip-x vv x0)

Flip polygon coordinates horizontally, by default around x=0.

poly-flip-y clj

(poly-flip-y vv)

(poly-flip-y vv y0)

Flip polygon coordinates vertically, by default around y=0.

TWOPI clj

2 Pi (360 degrees).

v-add clj

(v-add v1 v2)

Add a 2d geometric vector to another.

v-angle clj

(v-angle [x y])

Angle of a 2d geometric vector in radians in range -pi to pi.

v-dist clj

(v-dist v1 v2)

Distance from one 2d point to another.

v-dot clj

(v-dot v1 v2)

Dot product of two vectors.

v-interp clj

(v-interp v1 v2 frac)

Find a point frac fraction of the way from v1 to v2 by linear interpolation.

v-mag clj

(v-mag [x y])

Magnitude of a 2d geometric vector

v-scale clj

(v-scale v)

(v-scale [x y] s)

Multiply elements of a 2d vector by a scalar; Default is to normalise to unit length.

v-sub clj

(v-sub v1 v2)

Subtract a 2d geometric vector from another (v1 - v2).

vertical-angle? clj

(vertical-angle? ang)

(vertical-angle? ang tol)

Is angle vertical, within +/- 1.5 degrees by default.

x-val clj

y-val clj