(ns scad-tarmi.util

(:require [scad-clj.model :as model]

[scad-tarmi.maybe :as maybe]))

(defn loft

"Link passed shapes by a series of convex hulls. By default, link by pairs.

([block]

(loft 2 1 block))

([chunk-size block]

(loft chunk-size 1 block))

([chunk-size step block]

{:pre [(integer? chunk-size)

(not (zero? chunk-size))

(integer? step)

(not (zero? step))]}

(let [block (remove nil? block)

n (count block)]

(cond

;; If no shapes are passed return nil.

(zero? n) nil

;; If one shape is passed, return it.

(= 1 n) (first block)

;; Hull other short input (partitioning would return an empty list).

(> chunk-size n) (apply model/hull block)

:else

(apply maybe/union

(map (partial apply model/hull)

(partition chunk-size step block)))))))

(defn radiate

"Link a series of shapes through a single, central shape."

[hub spokes]

(loft 2 2 (list* hub (interpose hub spokes))))