From b7d0a75f2534759a756345373fec5846609b9a88 Mon Sep 17 00:00:00 2001
From: "James B. Pollack" <jamesbradenpollack@gmail.com>
Date: Wed, 30 Dec 2015 11:46:16 -0800
Subject: [PATCH] dynamic lifetimes for particle systems

---
 examples/controllers/handControllerGrab.js | 34 ++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/examples/controllers/handControllerGrab.js b/examples/controllers/handControllerGrab.js
index 9652132c08..3ad1a21fd3 100644
--- a/examples/controllers/handControllerGrab.js
+++ b/examples/controllers/handControllerGrab.js
@@ -56,7 +56,6 @@ var LINE_ENTITY_DIMENSIONS = {
 
 var LINE_LENGTH = 500;
 var PICK_MAX_DISTANCE = 500; // max length of pick-ray
-
 //
 // near grabbing
 //
@@ -129,6 +128,7 @@ var USE_PARTICLE_BEAM_FOR_SEARCHING = true;
 var USE_ENTITY_LINES_FOR_MOVING = false;
 var USE_OVERLAY_LINES_FOR_MOVING = false;
 var USE_PARTICLE_BEAM_FOR_MOVING = true;
+var TEMPORARY_PARTICLE_BEAM_LIFETIME = 30;
 
 var USE_SPOTLIGHT = false;
 var USE_POINTLIGHT = false;
@@ -549,6 +549,14 @@ function MyController(hand) {
 
     };
 
+    this.renewParticleBeamLifetime = function(){
+        var props = Entities.getEntityProperties(this.particleBeam,"age");
+        Entities.editEntity(this.particleBeam,{
+            lifetime: TEMPORARY_PARTICLE_BEAM_LIFETIME + props.age // renew lifetime
+        })
+        var lifetime = Entities.getEntityProperties(this.particleBeam,"lfietime").lifetime;
+    }
+
     this.evalLightWorldTransform = function(modelPos, modelRot) {
 
         var MODEL_LIGHT_POSITION = {
@@ -1803,4 +1811,26 @@ function cleanup() {
 }
 
 Script.scriptEnding.connect(cleanup);
-Script.update.connect(update);
\ No newline at end of file
+Script.update.connect(update);
+
+// particle systems can end up hanging around if a user crashes or something else causes controller cleanup not to get called. 
+// we can't create the search system on-demand since it takes some time for the particles to reach their entire length.  
+// thus the system cannot have a fixed lifetime.  this loop updates the lifetimes and will stop updating if a user crashes.
+
+if(USE_PARTICLE_BEAM_FOR_SEARCHING===true || USE_PARTICLE_BEAM_FOR_SEARCHING ===true){
+Script.update.connect(renewParticleBeamLifetimes)
+}
+
+var sinceLastParticleLifetimeUpdate = 0;
+
+function renewParticleBeamLifetimes(deltaTime) {
+    //debounce this call since we don't want it 60x a second
+    sinceLastParticleLifetimeUpdate = sinceLastParticleLifetimeUpdate + deltaTime;
+    if (sinceLastParticleLifetimeUpdate > TEMPORARY_PARTICLE_BEAM_LIFETIME - 10) {
+        sinceLastParticleLifetimeUpdate = 0;
+    } else {
+        return;
+    }
+    rightController.renewParticleBeamLifetime();
+    leftController.renewParticleBeamLifetime();
+}
\ No newline at end of file