From 6d9c5856041ffd26eb1f06bbe03a463fb6fecb47 Mon Sep 17 00:00:00 2001
From: Brad Hefta-Gaub <brad@highfidelity.io>
Date: Fri, 26 Feb 2016 12:01:59 -0800
Subject: [PATCH] add fade between depths in depth reticle

---
 examples/depthReticle.js | 47 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 6 deletions(-)

diff --git a/examples/depthReticle.js b/examples/depthReticle.js
index a60e61d07c..a8afb80df2 100644
--- a/examples/depthReticle.js
+++ b/examples/depthReticle.js
@@ -12,17 +12,24 @@
 
 var APPARENT_2D_OVERLAY_DEPTH = 1.0;
 var APPARENT_MAXIMUM_DEPTH = 100.0; // this is a depth at which things all seem sufficiently distant
-var lastDepthCheckTime = 0;
+var lastDepthCheckTime = Date.now();
+var desiredDepth = APPARENT_2D_OVERLAY_DEPTH;
+var wasDepth = Reticle.depth; // depth at the time we changed our desired depth
+var desiredDepthLastSet = lastDepthCheckTime; // time we changed our desired depth
+var TIME_BETWEEN_DEPTH_CHECKS = 100;
+var TIME_TO_FADE_DEPTH = 50;
 
 Script.update.connect(function(deltaTime) {
-    var TIME_BETWEEN_DEPTH_CHECKS = 100;
-    var timeSinceLastDepthCheck = Date.now() - lastDepthCheckTime;
+    var now = Date.now();
+    var timeSinceLastDepthCheck = now - lastDepthCheckTime;
     if (timeSinceLastDepthCheck > TIME_BETWEEN_DEPTH_CHECKS) {
+        var newDesiredDepth = desiredDepth;
+        lastDepthCheckTime = now;
         var reticlePosition = Reticle.position;
 
         // first check the 2D Overlays
         if (Reticle.pointingAtSystemOverlay || Overlays.getOverlayAtPoint(reticlePosition)) {
-            Reticle.setDepth(APPARENT_2D_OVERLAY_DEPTH);
+            newDesiredDepth = APPARENT_2D_OVERLAY_DEPTH;
         } else {
             var pickRay = Camera.computePickRay(reticlePosition.x, reticlePosition.y);
 
@@ -37,11 +44,39 @@ Script.update.connect(function(deltaTime) {
             // If either the overlays or entities intersect, then set the reticle depth to 
             // the distance of intersection
             if (result.intersects) {
-                Reticle.setDepth(result.distance);
+                newDesiredDepth = result.distance;
             } else {
                 // if nothing intersects... set the depth to some sufficiently large depth
-                Reticle.setDepth(APPARENT_MAXIMUM_DEPTH);
+                newDesiredDepth = APPARENT_MAXIMUM_DEPTH;
             }
         }
+
+        // If the desired depth has changed, reset our fade start time
+        if (desiredDepth != newDesiredDepth) {
+            desiredDepthLastSet = now;
+            desiredDepth = newDesiredDepth;
+            wasDepth = Reticle.depth;
+        }
+    }
+
+    // move the reticle toward the desired depth
+    if (desiredDepth != Reticle.depth) {
+
+        // determine the time between now, and when we set our determined our desiredDepth
+        var elapsed = now - desiredDepthLastSet;
+        var distanceToFade = desiredDepth - wasDepth;
+        var percentElapsed = Math.min(1, elapsed / TIME_TO_FADE_DEPTH);
+
+        // special case to handle no fade settings
+        if (TIME_TO_FADE_DEPTH == 0) {
+            percentElapsed = 1;
+        }
+        var depthDelta = distanceToFade * percentElapsed;
+
+        var newDepth = wasDepth + depthDelta;
+        if (percentElapsed == 1) {
+            newDepth = desiredDepth;
+        }
+        Reticle.setDepth(newDepth);
     }
 });