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  <head>
    <meta charset='utf-8'>
    <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
    <meta name='mobile-web-app-capable' content='yes'>
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    <!-- Origin Trial Token, feature = WebXR Device API, origin = https://immersive-web.github.io, expires = 2018-08-28 -->
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    <title>Gamepad</title>

    <link href='css/common.css' rel='stylesheet'></link>

    <!--The polyfill is not needed for browser that have native API support,
        but is linked by these samples for wider compatibility.-->
    <!--script src='https://cdn.jsdelivr.net/npm/webxr-polyfill@latest/build/webxr-polyfill.js'></script-->
    <script src='js/xrray-polyfill.js' type='module'></script>
    <script src='js/webxr-polyfill.js'></script>

    <script src='js/webxr-button.js'></script>
  </head>
  <body>
    <header>
      <details open>
        <summary>Gamepad</summary>
        <p>
          This sample demonstrates using XRInputSource Gamepad button presses
          to change box color and joystick/touchpad input to move boxes in 2
          dimensions.
          <a class="back" href="./index.html">Back</a>
        </p>
      </details>
    </header>
    <div id="gamepad-details">
      <!-- Tables updated in real-time data from WebXR gamepads will be
           displayed here if requested. -->
    </div>
    <script type="module">
      import {Scene} from './js/cottontail/src/scenes/scene.js';
      import {Renderer, createWebGLContext} from './js/cottontail/src/core/renderer.js';
      import {Gltf2Node} from './js/cottontail/src/nodes/gltf2.js';
      import {QueryArgs} from './js/cottontail/src/util/query-args.js';
      import {FallbackHelper} from './js/cottontail/src/util/fallback-helper.js';
      import {Node} from './js/cottontail/src/core/node.js';
      import {PbrMaterial} from './js/cottontail/src/materials/pbr.js';
      import {BoxBuilder} from './js/cottontail/src/geometry/box-builder.js';
      import {mat4, vec3, quat} from './js/cottontail/src/math/gl-matrix.js';
      import {GamepadTableManager} from './js/gamepad-data-tables.js';

      // If requested, initialize the WebXR polyfill
      if (QueryArgs.getBool('allowPolyfill', false)) {
        var polyfill = new WebXRPolyfill();
      }

      // If requested, don't display the frame rate info.
      let hideStats = QueryArgs.getBool('hideStats', false);

      // Display HTML tables updated in real-time with gamepad data. Useful for
      // testing + debugging.
      let displayTables = QueryArgs.getBool('displayTables', false);
      let tableManager = null;
      if (displayTables) {
        tableManager = new GamepadTableManager();
      }

      // XR globals.
      let xrButton = null;
      let xrRefSpace = null;

      // WebGL scene globals.
      let gl = null;
      let renderer = null;
      let scene = new Scene();
      if (hideStats) {
        scene.enableStats(false);
      }
      scene.addNode(new Gltf2Node({url: '../media/gltf/cube-room/cube-room.gltf'}));
      scene.standingStats(true);

      let floorSize = 10;
      let floorPosition = [0, -floorSize / 2 + 0.01, 0];
      let floorNode = null;

      let boxTable = {};

      class GamepadBox {
        constructor(position) {
          this.position = position;
          let boxBuilder = new BoxBuilder();
          boxBuilder.pushCube([0, 0, 0], 0.4);
          let boxPrimitive = boxBuilder.finishPrimitive(renderer);
          let boxMaterial = new PbrMaterial();
          boxMaterial.baseColorFactor.value = [1, 0, 0, 1]; // red
          this.renderPrimitive = renderer.createRenderPrimitive(boxPrimitive, boxMaterial);

          this.node = new Node();
          this.node.addRenderPrimitive(this.renderPrimitive);
          scene.addNode(this.node);

          this.color_state = true;
          this.is_button_pressed = false;
        }

        toggle_color() {
          this.renderPrimitive.uniforms.baseColorFactor.value = this.color_state ?
              [0, 1, 0, 1] : // green
              [1, 0, 0, 1];  // red
          this.color_state = !this.color_state;
        }

        move(dx, dy) {
          const inv_speed = 100;
          let translation = [dx / inv_speed, dy / inv_speed, 0];
          vec3.add(this.position, this.position, translation);
        }

        // Returns true iff button which was previously pressed is not pressed
        // anymore. The WebXR + Gamepad APIs don't support button press events
        // which is why keeping track of the state this way is necessary.
        update_button_state(is_button_pressed) {
          let did_button_fire = this.is_button_pressed && !is_button_pressed;
          this.is_button_pressed = is_button_pressed;
          return did_button_fire;
        }
      }

      class GamepadBoxSet {
        constructor(button_count, y) {
          // Place the boxes in a horizontal line 2 meters in front of the user.
          this.boxes = [];
          let x_shift = button_count / 2;
          for (let x = 1; x <= button_count; ++x) {
            this.boxes.push(new GamepadBox([x - x_shift, y, -2]));
          }
        }

        update_state(gamepad) {
          // A button press (pressing and then releasing a button) will change
          // the associated box's color from red to green (or from green to red
          // if it's currently green).
          for (let i = 0; i < gamepad.buttons.length; ++i) {
            if (this.boxes[i].update_button_state(gamepad.buttons[i].pressed)) {
              this.boxes[i].toggle_color();
            }
          }

          if (gamepad.mapping == "xr-standard") {
            // Invert the y axis because gamepads follow the convention that -1
            // is up/forwards, but we want to have a forward joystick/touchpad
            // input result in forward motion for the box.

            // xr-standard Gamepads always have at least one touchpad/joystick.
            // Its button will always be in the second slot.
            let dx = gamepad.axes[0];
            let dy = -gamepad.axes[1];
            this.boxes[1].move(dx, dy);

            if (gamepad.axes.length >= 4 && gamepad.buttons.length >= 4) {
              // If an xr-standard Gamepad has a secondary touchpad/joystick, its
              // button will be in the 4th slot and it will use the second pair
              // of input axes.
              dx = gamepad.axes[2];
              dy = -gamepad.axes[3];
              this.boxes[3].move(dx, dy);
            }
          }
        }

        update() {
          // Update the matrix for each box so that they are rendered in the
          // correct positions.
          for (let box of this.boxes) {
            mat4.identity(box.node.matrix);
            mat4.translate(box.node.matrix, box.node.matrix, box.position);
          }
        }
      }

      function ProcessGamepad(gamepad, hand) {
        if (displayTables) {
          tableManager.update(gamepad, hand);
        }

        if (!(hand in boxTable)) {
          const y_positions = {
            "left" : 1,
            "right" : 2,
            "none" : 3,
          };
          boxTable[hand] = new GamepadBoxSet(gamepad.buttons.length, y_positions[hand]);
        }

        boxTable[hand].update_state(gamepad);
      }

      function initXR() {
        xrButton = new XRDeviceButton({
          onRequestSession: onRequestSession,
          onEndSession: (session) => session.end(),
          supportedSessionTypes: ['immersive-vr']
        });
        document.querySelector('header').appendChild(xrButton.domElement);
      }

      function initGL() {
        if (gl)
          return;

        gl = createWebGLContext({
          xrCompatible: true
        });
        document.body.appendChild(gl.canvas);

        function onResize() {
          gl.canvas.width = (gl.canvas.offsetWidth * window.devicePixelRatio);
          gl.canvas.height = (gl.canvas.offsetHeight * window.devicePixelRatio);
        }
        window.addEventListener('resize', onResize);
        onResize();

        renderer = new Renderer(gl);

        scene.setRenderer(renderer);
        scene.inputRenderer.setControllerMesh(new Gltf2Node({url: '../media/gltf/controller/controller.gltf'}));

        addFloorBox();
      }

      function addFloorBox() {
        let boxBuilder = new BoxBuilder();
        boxBuilder.pushCube([0, 0, 0], floorSize);
        let boxPrimitive = boxBuilder.finishPrimitive(renderer);

        let boxMaterial = new PbrMaterial();
        boxMaterial.baseColorFactor.value = [0.3, 0.3, 0.3, 1.0];
        let boxRenderPrimitive = renderer.createRenderPrimitive(boxPrimitive, boxMaterial);

        floorNode = new Node();
        floorNode.addRenderPrimitive(boxRenderPrimitive);
        floorNode.selectable = true;
        scene.addNode(floorNode);
        mat4.identity(floorNode.matrix);
        mat4.translate(floorNode.matrix, floorNode.matrix, floorPosition);
      }

      function onRequestSession() {
        navigator.xr.requestSession('immersive-vr').then((session) => {
          xrButton.setSession(session);
          onSessionStarted(session);
        });
      }

      function onSessionStarted(session) {
        session.addEventListener('end', () => xrButton.setSession(null));

        initGL();

        session.updateRenderState({
          baseLayer : new XRWebGLLayer(session, gl)
        });

        session.requestReferenceSpace('local-floor').then((refSpace) => {
          // Save the session-specific reference space.
          xrRefSpace = refSpace;
          session.requestAnimationFrame(onXRFrame);
        });
      }

      function onXRFrame(time, frame) {
        let session = frame.session;
        let pose = frame.getViewerPose(xrRefSpace);
        scene.startFrame();
        session.requestAnimationFrame(onXRFrame);

        for (let source of session.inputSources) {
          if (source.gamepad) {
            ProcessGamepad(source.gamepad, source.handedness);
          }
        }

        if (displayTables) {
          tableManager.nextFrame();
        }

        for (let hand in boxTable) {
          boxTable[hand].update();
        }

        scene.updateInputSources(frame, xrRefSpace);
        scene.drawXRFrame(frame, pose);
        scene.endFrame();
      }

      // Start the XR application.
      initXR();
    </script>
  </body>
</html>