samples/03-vr-presentation.html

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Copyright 2016 The Chromium Authors. All rights reserved.
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    <title>03 - VR Presentation</title>

    <!--
      This sample demonstrates how to present the contents of a WebGL canvas to
      a VRDisplay. The content is not mirrored on the main display while being
      presented.
    -->

    <style>
      #webgl-canvas, #presenting-message {
        box-sizing: border-box;
        height: 100%;
        left: 0;
        margin: 0;
        position: absolute;
        top: 0;
        width: 100%;
      }
      #presenting-message {
        color: white;
        font-family: sans-serif;
        font-size: 2em;
        font-weight: bold;
        z-index: 1;
        text-align: center;
        padding: 0.5em;
        background-color: #444;
        display: none;
      }
    </style>

    <!-- This entire block in only to facilitate dynamically enabling and
    disabling the WebVR polyfill, and is not necessary for most WebVR apps.
    If you want to use the polyfill in your app, just include the js file and
    everything will work the way you want it to by default. -->
    <script src="js/third-party/webvr-polyfill.js"></script>
    <script src="js/third-party/wglu/wglu-url.js"></script>
    <script>
      // Dynamically turn the polyfill on if requested by the query args.
      if (WGLUUrl.getBool('polyfill', false)) {
        var polyfill = new WebVRPolyfill({
          // Ensures the polyfill is always active on mobile, due to providing
          // a polyfilled CardboardVRDisplay when no native API is available,
          // and also polyfilling even when the native API is available, due to
          // providing a CardboardVRDisplay when no native VRDisplays exist.
          PROVIDE_MOBILE_VRDISPLAY: true,
          // Polyfill optimizations
          DIRTY_SUBMIT_FRAME_BINDINGS: true,
          BUFFER_SCALE: 0.75,
        });
      }
    </script>
    <!-- End sample polyfill enabling logic -->

    <script src="js/third-party/gl-matrix-min.js"></script>

    <script src="js/third-party/wglu/wglu-program.js"></script>
    <script src="js/third-party/wglu/wglu-stats.js"></script>
    <script src="js/third-party/wglu/wglu-texture.js"></script>

    <script src="js/vr-cube-sea.js"></script>
    <script src="js/vr-samples-util.js"></script>
  </head>
  <body>
    <canvas id="webgl-canvas"></canvas>
    <div id="presenting-message">Put on your headset now</div>
    <script>
      /* global mat4, VRCubeSea, WGLUStats, WGLUTextureLoader, VRSamplesUtil */
      (function () {
      "use strict";

      var vrDisplay = null;
      var frameData = null;
      var projectionMat = mat4.create();
      var viewMat = mat4.create();

      var vrPresentButton = null;
      var presentingMessage = document.getElementById("presenting-message");

      // ===================================================
      // WebGL scene setup. This code is not WebVR specific.
      // ===================================================

      // WebGL setup.
      var gl = null;
      var cubeSea = null;
      var stats = null;

      function onContextLost( event ) {
        event.preventDefault();
        console.log( 'WebGL Context Lost.' );
        gl = null;
        cubeSea = null;
        stats = null;
      }

      function onContextRestored( event ) {
        console.log( 'WebGL Context Restored.' );
        initWebGL();
      }

      var webglCanvas = document.getElementById("webgl-canvas");
      webglCanvas.addEventListener( 'webglcontextlost', onContextLost, false );
      webglCanvas.addEventListener( 'webglcontextrestored', onContextRestored, false );

      function initWebGL() {
        var glAttribs = {
          alpha: false,
        };
        var useWebgl2 = WGLUUrl.getBool('webgl2', false);
        var contextTypes = useWebgl2 ? ["webgl2"] : ["webgl", "experimental-webgl"];

        for (var i in contextTypes) {
          gl = webglCanvas.getContext(contextTypes[i], glAttribs);
          if (gl)
            break;
        }
        if (!gl) {
          var webglType = (useWebgl2 ? "WebGL 2" : "WebGL")
          VRSamplesUtil.addError("Your browser does not support " + webglType + ".");
          return;
        }
        gl.clearColor(0.1, 0.2, 0.3, 1.0);
        gl.enable(gl.DEPTH_TEST);
        gl.enable(gl.CULL_FACE);

        var textureLoader = new WGLUTextureLoader(gl);
        var texture = textureLoader.loadTexture("media/textures/cube-sea.png");
        cubeSea = new VRCubeSea(gl, texture);

        var enablePerformanceMonitoring = WGLUUrl.getBool(
            'enablePerformanceMonitoring', false);
        stats = new WGLUStats(gl, enablePerformanceMonitoring);

        // Wait until we have a WebGL context to resize and start rendering.
        window.addEventListener("resize", onResize, false);
        onResize();
      }
      initWebGL();


      // ================================
      // WebVR-specific code begins here.
      // ================================

      function onVRRequestPresent () {
        // This can only be called in response to a user gesture.
        vrDisplay.requestPresent([{ source: webglCanvas }]).then(function () {
          // Nothing to do because we're handling things in onVRPresentChange.
        }, function (err) {
          var errMsg = "requestPresent failed.";
          if (err && err.message) {
            errMsg += "<br/>" + err.message
          }
          VRSamplesUtil.addError(errMsg, 2000);
        });
      }

      function onVRExitPresent () {
        // No sense in exiting presentation if we're not actually presenting.
        // (This may happen if we get an event like vrdisplaydeactivate when
        // we weren't presenting.)
        if (!vrDisplay.isPresenting)
          return;

        vrDisplay.exitPresent().then(function () {
          // Nothing to do because we're handling things in onVRPresentChange.
        }, function (err) {
          var errMsg = "exitPresent failed.";
          if (err && err.message) {
            errMsg += "<br/>" + err.message
          }
          VRSamplesUtil.addError(errMsg, 2000);
        });
      }

      function onVRPresentChange () {
        // When we begin or end presenting, the canvas should be resized to the
        // recommended dimensions for the display.
        onResize();

        if (vrDisplay.isPresenting) {
          if (vrDisplay.capabilities.hasExternalDisplay) {
            // Because we're not mirroring any images on an external screen will
            // freeze while presenting. It's better to replace it with a message
            // indicating that content is being shown on the VRDisplay.
            presentingMessage.style.display = "block";

            // On devices with an external display the UA may not provide a way
            // to exit VR presentation mode, so we should provide one ourselves.
            VRSamplesUtil.removeButton(vrPresentButton);
            vrPresentButton = VRSamplesUtil.addButton("Exit VR", "E", "media/icons/cardboard64.png", onVRExitPresent);
          }
        } else {
          // If we have an external display take down the presenting message and
          // change the button back to "Enter VR".
          if (vrDisplay.capabilities.hasExternalDisplay) {
            presentingMessage.style.display = "";

            VRSamplesUtil.removeButton(vrPresentButton);
            vrPresentButton = VRSamplesUtil.addButton("Enter VR", "E", "media/icons/cardboard64.png", onVRRequestPresent);
          }
        }
      }

      if (navigator.getVRDisplays) {
        frameData = new VRFrameData();

        navigator.getVRDisplays().then(function (displays) {
          if (displays.length > 0) {
            vrDisplay = displays[displays.length - 1];

            // It's heighly reccommended that you set the near and far planes to
            // something appropriate for your scene so the projection matricies
            // WebVR produces have a well scaled depth buffer.
            vrDisplay.depthNear = 0.1;
            vrDisplay.depthFar = 1024.0;

            // Generally, you want to wait until VR support is confirmed and
            // you know the user has a VRDisplay capable of presenting connected
            // before adding UI that advertises VR features.
            if (vrDisplay.capabilities.canPresent)
              vrPresentButton = VRSamplesUtil.addButton("Enter VR", "E", "media/icons/cardboard64.png", onVRRequestPresent);

            // For the benefit of automated testing. Safe to ignore.
            if (vrDisplay.capabilities.canPresent && WGLUUrl.getBool('canvasClickPresents', false))
              webglCanvas.addEventListener("click", onVRRequestPresent, false);

            // The UA may kick us out of VR present mode for any reason, so to
            // ensure we always know when we begin/end presenting we need to
            // listen for vrdisplaypresentchange events.
            window.addEventListener('vrdisplaypresentchange', onVRPresentChange, false);

            // These events fire when the user agent has had some indication that
            // it would be appropariate to enter or exit VR presentation mode, such
            // as the user putting on a headset and triggering a proximity sensor.
            // You can inspect the `reason` property of the event to learn why the
            // event was fired, but in this case we're going to always trust the
            // event and enter or exit VR presentation mode when asked.
            window.addEventListener('vrdisplayactivate', onVRRequestPresent, false);
            window.addEventListener('vrdisplaydeactivate', onVRExitPresent, false);
          } else {
            VRSamplesUtil.addInfo("WebVR supported, but no VRDisplays found.", 3000);
          }
        }, function () {
          VRSamplesUtil.addError("Your browser does not support WebVR. See <a href='http://webvr.info'>webvr.info</a> for assistance.");
        });
      } else if (navigator.getVRDevices) {
        VRSamplesUtil.addError("Your browser supports WebVR but not the latest version. See <a href='http://webvr.info'>webvr.info</a> for more info.");
      } else {
        VRSamplesUtil.addError("Your browser does not support WebVR. See <a href='http://webvr.info'>webvr.info</a> for assistance.");
      }

      function onResize () {
        if (vrDisplay && vrDisplay.isPresenting) {
          // If we're presenting we want to use the drawing buffer size
          // recommended by the VRDevice, since that will ensure the best
          // results post-distortion.
          var leftEye = vrDisplay.getEyeParameters("left");
          var rightEye = vrDisplay.getEyeParameters("right");

          // For simplicity we're going to render both eyes at the same size,
          // even if one eye needs less resolution. You can render each eye at
          // the exact size it needs, but you'll need to adjust the viewports to
          // account for that.
          webglCanvas.width = Math.max(leftEye.renderWidth, rightEye.renderWidth) * 2;
          webglCanvas.height = Math.max(leftEye.renderHeight, rightEye.renderHeight);
        } else {
          // We only want to change the size of the canvas drawing buffer to
          // match the window dimensions when we're not presenting.
          webglCanvas.width = webglCanvas.offsetWidth * window.devicePixelRatio;
          webglCanvas.height = webglCanvas.offsetHeight * window.devicePixelRatio;
        }
      }

      // Listen for click events on the canvas, which may come from something
      // like a Cardboard viewer or other VR controller, and make a small change
      // to the scene in response (so that we know it's working.) This basic
      // interaction mode is the baseline for all WebVR compatible devices, and
      // should ideally always be minimally supported.
      function onClick () {
        // Reset the background color to a random value
        if (gl) {
          gl.clearColor(
            Math.random() * 0.5,
            Math.random() * 0.5,
            Math.random() * 0.5, 1.0);
        }
      }

      // Register for mouse restricted events while in VR
      // (e.g. mouse no longer available on desktop 2D view)
      function onDisplayPointerRestricted() {
        if (webglCanvas && webglCanvas.requestPointerLock) {
          webglCanvas.requestPointerLock();
        }
      }

      // Register for mouse unrestricted events while in VR
      // (e.g. mouse once again available on desktop 2D view)
      function onDisplayPointerUnrestricted() {
        var lock = document.pointerLockElement;
        if (lock && lock === webglCanvas && document.exitPointerLock) {
          document.exitPointerLock();
        }
      }

      // This utility function monitors clicks from gamepads that are associated
      // with a VRDisplay and fires the callback, providing "click" support for
      // browsers that don't fire mouse click events on interaction.
      VRSamplesUtil.addVRClickListener(onClick);

      webglCanvas.addEventListener("click", onClick, false);
      window.addEventListener('vrdisplaypointerrestricted', onDisplayPointerRestricted);
      window.addEventListener('vrdisplaypointerunrestricted', onDisplayPointerUnrestricted);

      function onAnimationFrame (t) {
        // do not attempt to render if there is no available WebGL context
        if (!gl || !stats || !cubeSea) {
          return;
        }

        stats.begin();

        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

        if (vrDisplay) {
          // When presenting content to the VRDisplay we want to update at its
          // refresh rate if it differs from the refresh rate of the main
          // display. Calling VRDisplay.requestAnimationFrame ensures we render
          // at the right speed for VR.
          vrDisplay.requestAnimationFrame(onAnimationFrame);

          // As a general rule you want to get the pose as late as possible
          // and call VRDisplay.submitFrame as early as possible after
          // retrieving the pose. Do any work for the frame that doesn't need
          // to know the pose earlier to ensure the lowest latency possible.
          //var pose = vrDisplay.getPose();
          vrDisplay.getFrameData(frameData);

          if (vrDisplay.isPresenting) {
            // When presenting render a stereo view.
            gl.viewport(0, 0, webglCanvas.width * 0.5, webglCanvas.height);
            cubeSea.render(frameData.leftProjectionMatrix, frameData.leftViewMatrix, stats, t);

            gl.viewport(webglCanvas.width * 0.5, 0, webglCanvas.width * 0.5, webglCanvas.height);
            cubeSea.render(frameData.rightProjectionMatrix, frameData.rightViewMatrix, stats, t);

            // If we're currently presenting to the VRDisplay we need to
            // explicitly indicate we're done rendering.
            vrDisplay.submitFrame();
          } else {
            // When not presenting render a mono view that still takes pose into
            // account.
            gl.viewport(0, 0, webglCanvas.width, webglCanvas.height);
            // It's best to use our own projection matrix in this case, but we can use the left eye's view matrix
            mat4.perspective(projectionMat, Math.PI*0.4, webglCanvas.width / webglCanvas.height, 0.1, 1024.0);
            cubeSea.render(projectionMat, frameData.leftViewMatrix, stats, t);
            stats.renderOrtho();
          }
        } else {
          window.requestAnimationFrame(onAnimationFrame);

          // No VRDisplay found.
          gl.viewport(0, 0, webglCanvas.width, webglCanvas.height);
          mat4.perspective(projectionMat, Math.PI*0.4, webglCanvas.width / webglCanvas.height, 0.1, 1024.0);
          mat4.identity(viewMat);
          cubeSea.render(projectionMat, viewMat, stats, t);

          stats.renderOrtho();
        }

        stats.end();
      }
      window.requestAnimationFrame(onAnimationFrame);
      })();
    </script>
  </body>
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