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Contents

geom.voxel examples

Namespaces used by all the examples

[thi.ng.geom.core :as g]
[thi.ng.geom.vector :refer [vec3]]
[thi.ng.geom.voxel.svo :as svo]
[thi.ng.geom.voxel.isosurface :as iso]
[thi.ng.geom.mesh.io :as mio]
[thi.ng.math.core :as m]
[clojure.java.io :as io]

Example: Gyroid function contained in two boxes

This is a render of the voxel mesh generated with the code below:

../../../assets/svo-d7.jpg

(ns thi.ng.geom.examples.voxel.ex01
  (:require
   <<default-requires>>))

(def res (double 1/8))
(def wall 0.25)

(defn gyroid ^double [s t p]
  "Evaluates gyroid function at scaled point `p`."
  (let [[x y z] (m/* p s)]
    (- (m/abs*
        (+ (* (Math/cos x) (Math/sin z))
           (* (Math/cos y) (Math/sin x))
           (* (Math/cos z) (Math/sin y))))
       t)))

(defn voxel-box
  ([tree op flt r]
   (voxel-box tree op flt r r r))
  ([tree op flt rx ry rz]
   (->> (for [x rx y ry, z rz] (vec3 x y z))
        (filter flt)
        (svo/apply-voxels op tree))))

(time
 (def v
   (reduce
    (fn [tree [op r]] (voxel-box tree op identity r))
    (svo/voxeltree 32 res)
    [[svo/set-at (range 10 20 res)] [svo/set-at (range 15 25 res)]])))

(time
 (def v2
   (reduce
    (fn [tree [op r]] (voxel-box tree op identity r))
    v [[svo/delete-at (range (+ 10 wall) (- 20 wall) res)]
       [svo/delete-at (range (+ 15 wall) (- 25 wall) res)]])))

(time
 (def v3
   (reduce
    (fn [tree [op r]]
      (voxel-box tree op #(m/in-range? 0.0 10.0 (gyroid 1.0 1.2 %)) r))
    v2 [[svo/set-at (range (+ 10 wall) (- 20 wall) res)]
        [svo/set-at (range (+ 15 wall) (- 25 wall) res)]])))

(time
 (def v4
   (reduce
    (fn [tree [op rx ry rz]] (voxel-box tree op identity rx ry rz))
    v3 [[svo/delete-at (range 9 26 res) (range 9 26 res) (range 18 26 res)]])))

(time
 (with-open [o (io/output-stream "voxel.stl")]
   (mio/write-stl
    (mio/wrapped-output-stream o)
    (g/tessellate (iso/surface-mesh v4 11 0.5)))))

Example: Sphere erosion

../../../assets/svo-sphere-erosion.jpg

(ns thi.ng.geom.examples.voxel.ex02
  (:require
   <<default-requires>>))

(def res (double 1/4))
(def num-holes 30)

(defn voxel-sphere
  ([tree op o r res]
   (let [rg (range (- r) (+ r res) res)]
     (->> (for [x rg y rg, z rg
                :let [v (vec3 x y z)]
                :when (<= (m/mag v) r)] (m/+ o v))
          (svo/apply-voxels op tree)))))

(time
 (def v
   (reduce
    (fn [tree [op o r]] (voxel-sphere tree op o r res))
    (svo/voxeltree 32 res)
    (concat
     [[svo/set-at (vec3 15 15 15) 14]]
     (repeatedly
      num-holes
      #(vector
        svo/delete-at
        (vec3 (m/random 32) (m/random 32) (m/random 32))
        (m/random 4 8)))))))

(time
   (with-open [o (io/output-stream "sphere.stl")]
     (mio/write-stl
      (mio/wrapped-output-stream o)
      (g/tessellate (iso/surface-mesh v 10 0.5)))))

Example: 3D Gradient Noise

../../../assets/svo-simplexnoise.jpg

(ns thi.ng.geom.examples.voxel.ex03
  (:require
   <<default-requires>>
   [thi.ng.math.noise :as n]))

(def res (double 1/4))
(def n-scale 0.1)
(def iso-val 0.33)

(def v
  (let [r (range 1 31 res)]
    (->> (for [x r y r z r
               :when (<= iso-val (m/abs* (n/noise3 (* x n-scale) (* y n-scale) (* z n-scale))))]
           (vec3 x y z))
         (svo/apply-voxels svo/set-at (svo/voxeltree 32 res)))))

(time
 (with-open [o (io/output-stream "noise.stl")]
   (mio/write-stl
    (mio/wrapped-output-stream o)
    (g/tessellate (iso/surface-mesh v 10 iso-val)))))