create nameTag.js script

Running the script creates a text entity that will hover over the users
head showing their display name.

scripts/system/nameTag.js

@@ -0,0 +1,98 @@
+"use strict";
+
+/*jslint vars: true, plusplus: true*/
+/*global Entities, Script, Quat, Vec3, MyAvatar, print*/
+// nameTag.js
+//
+// Created by Triplelexx on 17/01/31
+// Copyright 2017 High Fidelity, Inc.
+//
+//
+// Distributed under the Apache License, Version 2.0.
+// See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+
+const NAMETAG_DIMENSIONS = {
+    x: 1.0,
+    y: 0.2,
+    z: 1.0
+}
+
+const CLIENTONLY = false;
+const NULL_UUID = "{00000000-0000-0000-0000-000000000000}";
+const ENTITY_CHECK_INTERVAL = 5000; // ms = 5 seconds
+const STARTUP_DELAY = 2000; // ms = 2 second
+const OLD_AGE = 3500; // we recreate the entity if older than this time in seconds 
+const TTL = 2; // time to live in seconds if script is not running
+const HEIGHT_ABOVE_HEAD = 0.2;
+const HEAD_OFFSET = -0.025;
+
+var nametagEntityID = NULL_UUID;
+var lastCheckForEntity = 0;
+
+// create the name tag entity after a brief delay
+Script.setTimeout(function() {
+    addNameTag();
+}, STARTUP_DELAY);
+
+function addNameTag() {
+    var nametagPosition = Vec3.sum(MyAvatar.getHeadPosition(), Vec3.multiply(HEAD_OFFSET, Quat.getFront(MyAvatar.orientation)));
+    nametagPosition.y += HEIGHT_ABOVE_HEAD;
+    var modelNameTagProperties = {
+        type: 'Text',
+        text: MyAvatar.displayName,
+        parentID: MyAvatar.sessionUUID,
+        dimensions: NAMETAG_DIMENSIONS,
+        position: nametagPosition
+    }
+    nametagEntityID = Entities.addEntity(modelNameTagProperties, CLIENTONLY);
+}
+
+function deleteNameTag() {
+    if(nametagEntityID !== NULL_UUID) {
+        Entities.deleteEntity(nametagEntityID);
+        nametagEntityID = NULL_UUID;
+    }
+}
+
+// cleanup on ending
+Script.scriptEnding.connect(cleanup);
+function cleanup() {
+    deleteNameTag();
+}
+
+Script.update.connect(update);
+function update() {
+    // bail if no entity
+    if(nametagEntityID == NULL_UUID) {
+        return;
+    }
+
+    if(Date.now() - lastCheckForEntity > ENTITY_CHECK_INTERVAL) {
+        checkForEntity();
+        lastCheckForEntity = Date.now();
+    }
+}
+
+function checkForEntity() {
+    var nametagProps = Entities.getEntityProperties(nametagEntityID);
+
+    // it is possible for the age to not be a valid number, we check for this and bail accordingly
+    if(nametagProps.age < 1) {
+        return;
+    }
+    
+    // it's too old make a new one, otherwise update
+    if(nametagProps.age > OLD_AGE || nametagProps.age == undefined) {
+        deleteNameTag();
+        addNameTag();
+    } else {
+        var nametagPosition = Vec3.sum(MyAvatar.getHeadPosition(), Vec3.multiply(HEAD_OFFSET, Quat.getFront(MyAvatar.orientation)));
+        nametagPosition.y += HEIGHT_ABOVE_HEAD;
+        Entities.editEntity(nametagEntityID, {
+            position: nametagPosition,
+            // lifetime is in seconds we add TTL on top of the next poll time
+            lifetime: Math.round(nametagProps.age) + (ENTITY_CHECK_INTERVAL / 1000) + TTL,
+            text: MyAvatar.displayName
+        });
+    }
+}