clunk.util — com.kimbsy/clunk 0.7.1

center clj

(center window)

The [x y] position vector at the center of the screen.

centre clj

convex? clj

(convex? poly)

Are all the corners of the polygon turning in the same direction?

cross clj

(cross [ax ay az] [bx by bz])

Calculate the cross product of two vectors.

direction-vector clj

(direction-vector r)

Calculate the unit direction vector based on the rotation angle.

ellipse-points clj

(ellipse-points [w h] & {:keys [num-points] :or {num-points 32}})

Generate a collection of [x y] points in CCW order around an ellipse with dimensions [w h].

The points are all in the [+x +y] quadrant so the clunk.sprite/pos-offsets function works by default.

invert clj

(invert v)

Multiply each component of the vector by -1.

Represents a rotation of 180 degrees.

left-turn? clj

(left-turn? [ax ay] [bx by] [cx cy])

Is the corner from A->B->C a left turn?

magnitude clj

(magnitude v)

Calculate the length of a vector.

normalize clj

(normalize v)

Calculate the unit vector of a given vector.

We calculate the reciprocal of the magnitude of the vector and multiply the components by this factor to avoid multiple division operations.

orthogonals clj

(orthogonals [x y])

Calculate the two orthogonal vectors to a given 2D vector.

Y axis is inverted so this returns [90-degrees-right-vector 90-degrees-left-vector]

poly-lines clj

(poly-lines poly)

Construct the lines that make up a polygon from its points.

pos-in-tri? clj

(pos-in-tri? pos [a b c])

Is the position pos inside the triangle ABC?

remove-nth clj

(remove-nth n xs)

Remove the nth element from a collection.

rotate-vector clj

(rotate-vector [x y :as v] r)

Rotate a vector about the origin by r degrees.

Checks first for r representing an integer number of rotations, in with case the vector will be unchanged.

rotation-angle clj

(rotation-angle [x y])

Calculate the rotation angle of a vector.

split-by clj

(split-by pred coll)

Split a collection using a predicate.

Returns [things-that-were-true things-that-were-false].

squared-magnitude clj

(squared-magnitude [x y z])

Sum the squares of the components of a vector.

The if check on z is a lot faster than doing an apply or reduce across the vector.

triangulate clj

(triangulate poly)

Split a concave polygon with no holes or overlapping edges into a collection of triangles which can be drawn.

unit-vector clj

(unit-vector v)

Calculate the unit vector of a given vector.

v< clj

(v< a b)

Determine if the magnitude of a vector a is less than the magnitude of vector b.

We can just compare the component squares to avoid the costly sqrt operations.

v<= clj

(v<= a b)

Determine if the magnitude of a vector a is less than or equal to the magnitude of vector b.

We can just compare the component squares to avoid the costly sqrt operations.

window-pos clj

(window-pos window [x-factor y-factor])

Create an [x y] position vector at the specified ratio coordinates.

window-size clj

(window-size window)

zero-vector? clj

(zero-vector? v)

Predicate to check if a vector has length 0.