added basic nft example

Author: kalwalt

README.md

@@ -136,6 +136,8 @@ The basic operation goes like this:
 5. Add a `'getMarker'` event listener
 6. Call `ARController.process(img)`
 
+### Basic example with an image source and a pattern marker ( hiro )
+
 ```js
 <script src="../build/artoolkit.min.js"></script>
 <script>
@@ -169,6 +171,45 @@ The basic operation goes like this:
 </script>
 ```
 
+### Basic example with a worker and a NFT marker
+
+```js
+<div id="container">
+    <video id="video"></video>
+    <canvas style="position: absolute; left:0; top:0" id="canvas_draw"></canvas>
+</div>
+// main worker create the web worker see in the examples/nft_improved_worker for details
+<script src="main_worker.js"></script>
+<script>
+var container = document.getElementById('container');
+var video = document.getElementById('video');
+var canvas_draw = document.getElementById('canvas_draw');
+
+if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
+    var hint = {};
+    if (isMobile()) {
+        hint = {
+            facingMode: {"ideal": "environment"},
+            audio: false,
+            video: {
+                width: {min: 240, max: 240},
+                height: {min: 360, max: 360},
+            },
+        };
+    }
+
+    navigator.mediaDevices.getUserMedia({video: hint}).then(function (stream) {
+        video.srcObject = stream;
+        video.play();
+        video.addEventListener("loadedmetadata", function() {
+            start(container, markers["pinball"], video, video.videoWidth, video.videoHeight, canvas_draw, function() { statsMain.update() }, function() { statsWorker.update()) };
+        });
+    });
+}
+</script>
+```
+
+
 ## Constants
 
 *prepend all these constants with `Module.` or `artoolkit.CONSTANTS` to access them*