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| <html> |
| <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'> |
| <meta name='apple-mobile-web-app-capable' content='yes'> |
| |
| <!-- Origin Trial Token, feature = WebXR Device API, origin = https://immersive-web.github.io, expires = 2018-08-28 --> |
| <meta http-equiv="origin-trial" data-feature="WebXR Device API" data-expires="2018-08-28" content="AnNpu7ceXvLew05ccD8Zr1OZsdZiB2hLQKK82kTTMDwF7oRKtP3QEJ4RzkeHrmB8Sq0vSV6ZNmszpBCZ0I8p9gAAAABceyJvcmlnaW4iOiJodHRwczovL2ltbWVyc2l2ZS13ZWIuZ2l0aHViLmlvOjQ0MyIsImZlYXR1cmUiOiJXZWJYUkRldmljZSIsImV4cGlyeSI6MTUzNTQxNDQwMH0="> |
| |
| <title>Reduced Bind Rendering</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/webxr-polyfill.js'></script> |
| |
| <script src='js/webxr-button.js'></script> |
| </head> |
| <body> |
| <header> |
| <details open> |
| <summary>Reduced Bind Rendering</summary> |
| <p> |
| This sample demonstrates a simple technique to reduce the number of |
| state changes an application needs to make while rendering, potentially |
| enabling better performance. |
| <a class="back" href="./">Back</a> |
| </p> |
| </details> |
| </header> |
| <script type="module"> |
| import {WebXRView, Scene} from './js/cottontail/src/scenes/scene.js'; |
| import {Renderer, createWebGLContext} from './js/cottontail/src/core/renderer.js'; |
| import {QueryArgs} from './js/cottontail/src/util/query-args.js'; |
| import {CubeSeaNode} from './js/cottontail/src/nodes/cube-sea.js'; |
| import {FallbackHelper} from './js/cottontail/src/util/fallback-helper.js'; |
| |
| // If requested, initialize the WebXR polyfill |
| if (QueryArgs.getBool('allowPolyfill', false)) { |
| var polyfill = new WebXRPolyfill(); |
| } |
| |
| // XR globals. |
| let xrButton = null; |
| let xrImmersiveRefSpace = null; |
| let xrNonImmersiveRefSpace = null; |
| |
| // WebGL scene globals. |
| let gl = null; |
| let renderer = null; |
| let scene = new Scene(); |
| scene.addNode(new CubeSeaNode()); |
| |
| function initXR() { |
| xrButton = new XRDeviceButton({ |
| onRequestSession: onRequestSession, |
| onEndSession: onEndSession |
| }); |
| document.querySelector('header').appendChild(xrButton.domElement); |
| |
| if (navigator.xr) { |
| navigator.xr.supportsSessionMode('immersive-vr').then(() => { |
| xrButton.enabled = true; |
| }); |
| |
| navigator.xr.requestSession().then(onSessionStarted); |
| } else { |
| initFallback(); |
| } |
| } |
| |
| // This kicks off a really simple fallback rendering loop so that we don't |
| // have to clutter up the sample code with fallback rendering logic. This |
| // variant also has the benefit of including simple support for looking |
| // around via clicking and dragging with the right mouse button or a two- |
| // finger drag. |
| function initFallback() { |
| initGL(); |
| document.body.appendChild(gl.canvas); |
| let fallbackHelper = new FallbackHelper(scene, gl); |
| } |
| |
| function initGL() { |
| if (gl) |
| return; |
| |
| gl = createWebGLContext({ |
| xrCompatible: true |
| }); |
| // Set up a non-black clear color so that we can see if something renders wrong. |
| gl.clearColor(0.1, 0.2, 0.3, 1.0); |
| |
| renderer = new Renderer(gl); |
| |
| scene.setRenderer(renderer); |
| } |
| |
| function onRequestSession() { |
| navigator.xr.requestSession({ mode: 'immersive-vr' }).then((session) => { |
| xrButton.setSession(session); |
| onSessionStarted(session); |
| }); |
| } |
| |
| function onSessionStarted(session) { |
| session.addEventListener('end', onSessionEnded); |
| |
| initGL(); |
| |
| let outputCanvas = makeCanvas(); |
| document.body.appendChild(outputCanvas); |
| |
| session.updateRenderState({ |
| baseLayer: new XRWebGLLayer(session, gl), |
| outputContext: outputCanvas.getContext('xrpresent') |
| }); |
| |
| session.requestReferenceSpace({ type: 'stationary', subtype: 'eye-level' }).then((refSpace) => { |
| if (session.mode.startsWith('immersive')) { |
| xrImmersiveRefSpace = refSpace; |
| } else { |
| xrNonImmersiveRefSpace = refSpace; |
| } |
| session.requestAnimationFrame(onXRFrame); |
| }); |
| } |
| |
| function onEndSession(session) { |
| session.end(); |
| } |
| |
| function onSessionEnded(event) { |
| if (event.session.mode.startsWith('immersive')) { |
| xrButton.setSession(null); |
| } |
| |
| if (event.session.renderState.outputContext) { |
| document.body.removeChild(event.session.renderState.outputContext.canvas); |
| } |
| } |
| |
| function onXRFrame(t, frame) { |
| let session = frame.session; |
| let refSpace = session.mode.startsWith('immersive') ? |
| xrImmersiveRefSpace : |
| xrNonImmersiveRefSpace; |
| let pose = frame.getViewerPose(refSpace); |
| |
| scene.startFrame(); |
| |
| session.requestAnimationFrame(onXRFrame); |
| |
| if (pose) { |
| gl.bindFramebuffer(gl.FRAMEBUFFER, session.renderState.baseLayer.framebuffer); |
| gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); |
| |
| // This is a different rendering pattern than the previous samples |
| // used, but it should be more efficent. It's very common for apps |
| // being ported to XR to take existing 2D rendering code and call the |
| // top-level "drawScene" function once per XR view, effectively |
| // drawing a single eye at a time. However, this causes many state |
| // changes to be duplicated, which adds to the render loop's overhead. |
| // By providing the matrices and viewports as an array to the drawing |
| // function it can do all the necessary binding once and then call the |
| // actual draw commands in a tighter loop, only changing the matrices |
| // and viewport each time. This does mean that the viewport is changed |
| // much more frequently (N times per object instead of N times per |
| // scene) but it's typically a pretty cheap thing to change and will |
| // almost always be easily outweighed by the savings from not |
| // redundantly binding everything else. |
| |
| // For example, a traditional draw loop would do this: |
| |
| // Draw(views): |
| // for each view in views: |
| // setViewport(); |
| // for each object in scene: |
| // bindProgram(); |
| // bindMatrices(); |
| // bindUniforms(); |
| // bindBuffers(); |
| // bindTextures(); |
| // draw(); |
| |
| // While this method results in a loop more like this: |
| |
| // Draw(views): |
| // for each object in scene: |
| // bindProgram(); |
| // bindUniforms(); |
| // bindBuffers(); |
| // bindTextures(); |
| // for each view in views: |
| // setViewport(); |
| // bindMatrices(); |
| // draw(); |
| |
| // Note that for the complexity of the scene in this samples this |
| // won't make much visible performance difference, but we're using the |
| // more efficient pattern anyway as a way of promoting best practices. |
| |
| let views = []; |
| for (let view of pose.views) { |
| // Gather all the values needed for one view and push it into the |
| // array of views to be drawn. WebXRView is a utility class that |
| // holds all the necessary values for drawing a single view. |
| let renderView = new WebXRView(); |
| |
| // In future samples we'll hide this part away as well by using the |
| // scene.drawXRViews() function, which handles gathering these |
| // values internally. |
| renderView.projectionMatrix = view.projectionMatrix; |
| renderView.viewMatrix = view.viewMatrix; |
| renderView.viewport = session.renderState.baseLayer.getViewport(view); |
| views.push(renderView); |
| } |
| |
| scene.drawViewArray(views); |
| } |
| |
| scene.endFrame(); |
| } |
| |
| initXR(); |
| </script> |
| </body> |
| </html> |