Update app.py

app.py

@@ -707,7 +707,8 @@ async(c, o, p, d, n, m, s)=>{
         window.xold = 0;
         window.yold = 0;
         window.buffer = null;
-        window.ctx = null;
+        window.bufferCanvas = document.createElement("canvas");
+        window.ctx = bufferCanvas.getContext("2d", { willReadFrequently: true });
         window.video = document.getElementById("depth_video").getElementsByTagName("video")[0];
         window.parallax = 0;
         window.xdir = new BABYLON.Vector3(1, 0, 0);
@@ -772,7 +773,6 @@ async(c, o, p, d, n, m, s)=>{
 
         function requestMap() {
         try {
-        alert(video.videoWidth);
         alert(ctx);
           ctx.drawImage(video, 0, 0, video.videoWidth, video.videoHeight);
           if (buffer) {
@@ -792,10 +792,8 @@ async(c, o, p, d, n, m, s)=>{
           for (var i=0; i<videoDome.videoTexture.video.duration; i++) {
             document.getElementById('seek').innerHTML += '<a href="#" style="position:absolute;left:'+(56+coords[i].lng/2)+'px;top:'+(56-coords[i].lat/2)+'px;" onclick="seek('+i+');">-'+i+'-</a> ';
           }
-          const canvas = document.createElement("canvas");
-          canvas.width = video.videoWidth;
-          canvas.height = video.videoHeight;
-          ctx = canvas.getContext("2d", { willReadFrequently: true });
+          bufferCanvas.width = video.videoWidth;
+          bufferCanvas.height = video.videoHeight;
           
           videoPlay();
         };