From 2d10f00844e98c87dea635748ab494edd2ac1096 Mon Sep 17 00:00:00 2001
From: Sasha Kovar <sasha-git@arcocene.org>
Date: Sat, 13 May 2017 21:31:35 -0700
Subject: [PATCH] hollow sphere

---
 src/voxelburst/core.clj | 61 +++++++++++++++++++++++++++--------------
 1 file changed, 40 insertions(+), 21 deletions(-)

diff --git a/src/voxelburst/core.clj b/src/voxelburst/core.clj
index b3db4fb..b93063d 100644
--- a/src/voxelburst/core.clj
+++ b/src/voxelburst/core.clj
@@ -12,14 +12,8 @@
    ;;[thi.ng.geom.rect :as r]
    [thi.ng.geom.voxel.isosurface :as iso]
    [thi.ng.geom.voxel.svo :as svo]
-   ;;[thi.ng.luxor.core :refer :all]
-   ;;[thi.ng.luxor.io :as lio]
    [thi.ng.math.core :as m]
-   [clojure.math.numeric-tower :as math]
-   ;;[termite.sim :as sim]
-   ;;[termite.ui :as ui]
-   )
-  (:gen-class))
+   [clojure.math.numeric-tower :as math]))
 
 ;;;
 ;;; geometry
@@ -31,6 +25,9 @@
 (defn v-+ [v1 v2]
   (mapv + v1 v2))
 
+(defn v-- [v1 v2]
+  (mapv - v1 v2))
+
 (defn round-point [v]
   (map math/round v))
 
@@ -46,22 +43,28 @@
 ;;; trace
 ;;;
 
-(def start-radius 3.0)
-(def start-lifespan 100)
-(def radius-step (/ start-radius start-lifespan))
+(def start-radius 1.0)
+(def start-lifespan 120)
+(def radius-step 0 #_(/ start-radius start-lifespan))
 
-(defrecord Trace [position velocity radius lifespan])
+(defrecord Trace [position velocity radius lifespan start-time])
 
 (defn new-trace [origin]
-  (Trace. origin (random-vel) start-radius start-lifespan))
+  (Trace. origin (random-vel) start-radius start-lifespan (+ 70 (rand-int 10))))
+
+(defn drawing? [t bounds]
+  (and (in-bounds? (:position t) bounds)
+       (> (:radius t) 0)
+       (> (:lifespan t) 0)
+       (< (:start-time t) 0)))
 
 (defn update-trace [trace bounds]
   (let [t (Trace. (next-pos (:position trace) (:velocity trace))
                   (next-vel (:velocity trace))
                   (- (:radius trace) radius-step)
-                  (dec (:lifespan trace)))]
+                  (dec (:lifespan trace))
+                  (dec (:start-time trace)))]
     (if (and (in-bounds? (:position t) bounds)
-               (> (:radius t) 0)
                (> (:lifespan t) 0))
       t
       (do #_(println "died at " (:lifespan t))
@@ -71,14 +74,14 @@
 ;;; physics
 ;;;
 
-(def gravity [0 0 -0.1])
+(def gravity [0 0 0])
 
 (defn random-vel
   []
   #_(mapv #(* 2 (- % 0.5)) (repeatedly 3 rand))
   (vector (* 8 (- (rand) 0.5))
           (* 8 (- (rand) 0.5))
-          (* 12 (rand))))
+          (* 8 (- (rand) 0.5))))
 
 (defn next-pos
   "Position at t+1"
@@ -95,11 +98,27 @@
   [v [lo hi]]
   (and (>= v lo) (<= v hi)))
 
-(defn in-bounds?
-  "Is point inside the domain bounds?"
+#_(defn in-bounds?
+  "Inside bounds box?"
   [p bounds]
   (every? true? (map #(single-in-bounds? %1 %2) p bounds)))
 
+#_(defn complex-single-in-bounds?
+  "Is a single value in bounds?"
+  [v [lo hi]]
+  (and (>= v lo) (<= v hi)
+       (>= (math/abs v) (/ hi 5))))
+
+#_(defn in-bounds?
+  "Inside complex box?"
+  [p bounds]
+  (every? true? (map #(complex-single-in-bounds? %1 %2) p bounds)))
+
+(defn in-bounds?
+  "Inside sphere?"
+  [p bounds]
+  (<= (v-mag (v-- p [500 500 500])) 220))
+
 (defn trace-trajectory
   [trace bounds]
   (loop [traces []
@@ -107,7 +126,7 @@
     (let [new-trace (update-trace trace bounds)]
       (if (not new-trace)
         traces
-        (recur (conj traces trace) new-trace)))))
+        (recur (if (drawing? new-trace bounds) (conj traces trace) traces) new-trace)))))
 
 (defn trajectory-voxels [traces]
   (reduce set/union (map #(sphere (round-point (:position %)) (:radius %)) traces)))
@@ -134,11 +153,11 @@
         trace (sample-traces count)]
     (svo/apply-voxels svo/set-at tree trace)))
 
-(def sampletree (sample-tree 10))
+;;(def sampletree (sample-tree 10))
 
 (defn sample-write-ply
   [count]
   (time
    (with-open [o (io/output-stream "sample.ply")]
      (let [tree #_sampletree (sample-tree count)]
-       (mio/write-ply o (g/tessellate (iso/surface-mesh tree 5 0.85)))))))
+       (mio/write-ply o (g/tessellate (g/scale (iso/surface-mesh tree 5 0.9) 0.01)))))))