From b8565358ffc30cdf2f9e9f8ace48ce965682d942 Mon Sep 17 00:00:00 2001
From: Philip Rosedale <philip@highfidelity.io>
Date: Mon, 11 Jan 2016 09:16:33 -0800
Subject: [PATCH] Added basic energy bar example

---
 examples/example/ui/energyBar.js | 105 +++++++++++++++++++++++++++++++
 examples/libraries/utils.js      |   5 ++
 2 files changed, 110 insertions(+)
 create mode 100644 examples/example/ui/energyBar.js

diff --git a/examples/example/ui/energyBar.js b/examples/example/ui/energyBar.js
new file mode 100644
index 0000000000..b0abf6778b
--- /dev/null
+++ b/examples/example/ui/energyBar.js
@@ -0,0 +1,105 @@
+//  energyBar.js
+//  examples/ui
+//
+//  Created by Eric Levin on 1/4/15
+//  Copyright 2015 High Fidelity, Inc.
+//
+//  This script adds an energy bar overlay which displays the amount of energy a user has left for grabbing and moving objects
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+Script.include("../../libraries/utils.js");
+var energyColor = {red: 0, green: 200, blue: 0};
+var lowEnergyColor = {red: 255, green: 0, blue: 0};
+var totalWidth = 200;
+var paddingRight = 50;
+var xPosition = Window.innerWidth - totalWidth - paddingRight;
+var lowEnergyThreshold = 0.3;
+var currentEnergy = 1.0;
+var energyLossRate = 0.003;
+var energyChargeRate = 0.003;
+var isGrabbing = false;
+var refractoryPeriod = 2000;
+
+var lastAvatarVelocity = MyAvatar.getVelocity(); 
+var lastAvatarPosition = MyAvatar.position;
+
+var background = Overlays.addOverlay("text", {
+    x: xPosition,
+    y: 20,
+    width: totalWidth,
+    height: 10,
+    backgroundColor: {red: 184, green: 181, blue: 178}
+})
+
+var bar = Overlays.addOverlay("text", {
+    x: xPosition,
+    y: 20,
+    width: totalWidth,
+    height: 10,
+    backgroundColor: energyColor
+});
+
+
+// Takes an energy value between 0 and 1 and sets energy bar width appropriately
+function setEnergy(energy) {
+    energy = clamp(energy, 0, 1);
+    var barWidth = totalWidth * energy;
+    var color = energy <= lowEnergyThreshold ? lowEnergyColor: energyColor;
+    Overlays.editOverlay(bar, { width: barWidth, backgroundColor: color});
+}
+
+function avatarAccelerationEnergy() {
+    var AVATAR_MOVEMENT_ENERGY_CONSTANT = 0.001;
+    var velocity = MyAvatar.getVelocity(); 
+    var dV = Vec3.subtract(velocity, lastAvatarVelocity);
+    var dE = Vec3.length(lastAvatarVelocity) * Vec3.length(dV) * AVATAR_MOVEMENT_ENERGY_CONSTANT;
+    lastAvatarVelocity = velocity;  
+    if (dE > 0.01) {
+        print("de " + dE);
+    }
+    return dE;
+}
+
+function teleported() {
+    var MAX_AVATAR_MOVEMENT_PER_FRAME = 30.0;
+    var position = MyAvatar.position; 
+    var dP = Vec3.length(Vec3.subtract(position, lastAvatarPosition));
+    lastAvatarPosition = position;
+    return (dP > MAX_AVATAR_MOVEMENT_PER_FRAME);
+}
+
+function audioEnergy() {
+    var AUDIO_ENERGY_CONSTANT = 0.000001;
+    return MyAvatar.audioLoudness * AUDIO_ENERGY_CONSTANT;
+}
+
+function update() {
+    // refill energy
+    currentEnergy += energyChargeRate;
+
+    //  Avatar acceleration
+    currentEnergy -= avatarAccelerationEnergy();
+
+    // Teleport cost 
+    if (teleported()) {
+        currentEnergy = 0;
+    }
+
+    // Making sounds
+    currentEnergy -= audioEnergy(); 
+
+
+    currentEnergy = clamp(currentEnergy, 0, 1);
+    setEnergy(currentEnergy);
+}
+
+function cleanup() {
+    Overlays.deleteOverlay(background);
+    Overlays.deleteOverlay(bar);
+}
+
+Script.update.connect(update);
+Script.scriptEnding.connect(cleanup);
diff --git a/examples/libraries/utils.js b/examples/libraries/utils.js
index 115c1bcb65..b2b2902cb0 100644
--- a/examples/libraries/utils.js
+++ b/examples/libraries/utils.js
@@ -297,3 +297,8 @@ calculateHandSizeRatio = function() {
     var handSizeRatio = centerHandPoint/standardCenterHandPoint;
     return handSizeRatio;
 }
+
+clamp = function(val, min, max){
+     return Math.max(min, Math.min(max, val))
+ } 
+