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(ns canvas-fn.vectors
(:require [canvas-fn.util :as util]))
(defn vplus [a b]
"Add two vectors together"
[(+ (first a) (first b))
(+ (second a) (second b))])
(defn vsub [a b]
"Subtractor two vectors"
[(- (first a) (first b))
(- (second a) (second b))])
(defn vmult [vector factor]
"Multiply the vector by a factor"
[(* factor (first vector)) (* factor (second vector))])
(defn vdiv [vector dividend]
"Divide a vector by dividend"
[(/ (first vector) dividend) (/ (second vector) dividend)])
(defn vmagnitude [vector]
"The magnitude of the vector, an absolute number. Calculated as
square root of (x^2 + y^2)"
(let [x (first vector)
y (second vector)]
(->> (* x x)
(+ (* y y))
(.sqrt js/Math))))
(defn vnormalize [vector]
"Normalize the vector"
(let [magnitude (vmagnitude vector)]
(if (not= magnitude 0)
(vdiv vector magnitude)
(defn vlimit [vector max-magnitude]
"Limit the magnitude of the vector"
(if (> (vmagnitude vector) max-magnitude)
(vmult (vnormalize vector) max-magnitude)