Version: 2022.3
Language : English
Cache behavior in WebGL
Audio in WebGL

WebGL graphics

WebGLA JavaScript API that renders 2D and 3D graphics in a web browser. The Unity WebGL build option allows Unity to publish content as JavaScript programs which use HTML5 technologies and the WebGL rendering API to run Unity content in a web browser. More info
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is an API for rendering graphics in web browsers, which is based on the functionality of the OpenGL ES graphics library. WebGL 1.0 roughly matches OpenGL ES 2.0 functionality, and WebGL 2.0 roughly matches OpenGL ES 3.0 functionality.

Camera clear

By default, Unity WebGL clears the drawing buffer after each frame, which means the content of the frame buffer clears regardless of the Camera.clearFlags setting. However, you can change this behavior at instantiation time. To do this, set webglContextAttributes.preserveDrawingBuffer to true in your WebGL template:

script.onload = () => {
       config['webglContextAttributes'] = {"preserveDrawingBuffer": true}; // Add this line to the index.html file in a WebGL Template
       createUnityInstance(canvas, config, (progress) => }

Deferred rendering

Unity WebGL only supports Deferred Rendering Path if WebGL2.0 is available. On WebGL 1.0, Unity WebGL runtime falls back to Forward RenderingA rendering path that renders each object in one or more passes, depending on lights that affect the object. Lights themselves are also treated differently by Forward Rendering, depending on their settings and intensity. More info
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.

Global illumination

Unity WebGL only supports baked GI. Realtime Global IlluminationA group of techniques that model both direct and indirect lighting to provide realistic lighting results.
See in Glossary
isn’t currently supported in WebGL. In addition, Unity WebGL supports Non-Directional lightmapsA pre-rendered texture that contains the effects of light sources on static objects in the scene. Lightmaps are overlaid on top of scene geometry to create the effect of lighting. More info
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only.

Linear rendering

Unity WebGL only supports linear color space rendering with WebGL 2.0. Linear color space rendering doesn’t have fallback support for WebGL 1.0. To build a WebGL player using linear color space rendering, you need to remove WebGL 1.0 API in the Player settings, open the Other Settings panel, disable the Automatic Graphics API setting.

Some web browsers don’t support sRGB DXT texture compression. This can decrease the quality of rendering performance when using linear rendering, due to runtime decompression of all the DXT textures.

Video clip importer

You can’t use VideoClipImporter to import video clips to your Unity project, because it might increase the initial asset data download size and prevent network streaming. For video playback, use the URL option in the VideoPlayer component and place the asset in the StreamingAssets/ directory to use the built-in network streaming of your browser.

WebGL shader code restrictions

The WebGL 1.0 specification imposes some limitations on GLSLS shaderA program that runs on the GPU. More info
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code, which are more restrictive than most OpenGL ES 2.0 implementations. This is mostly relevant when you write your own shaders.

WebGL has specific restrictions on which values to use to index arrays or matrices. For example, WebGL only allows dynamic indexing with constant expressions, loop indices or a combination, except for uniform access in vertex shadersA program that runs on each vertex of a 3D model when the model is being rendered. More info
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, which you can index using any expression.

Note for WebGL 1.0: Additional restrictions apply on control structures in WebGL 1.0, where it doesn’t allow while loops and most type of for loops. However, it allows counting for loops, where the field initializer sets a variable to a constant, the update adds a constant to or subtracts a constant from the variable, and the continuation test compares the variable to a constant.

Note: Due to limited available memory in WebGL, you should avoid including unneeded shader variants which can lead to unnecessary memory usage. Therefore, Unity recommends familiarizing yourself with shader variantsA verion of a shader program that Unity generates according to a specific combination of shader keywords and their status. A Shader object can contain multiple shader variants. More info
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and shader stripping, and take extra care to ensure that you don’t add shaders with too many variants (for example, Unity’s Standard Shader) to the [Always-included Shaders] section(class-GraphicsSettings#Always) in Graphics Settings.

Font rendering

Unity WebGL supports dynamic font rendering similar to other Unity platforms. However, as it doesn’t have access to the fonts installed on the user’s machine, if you want to use any fonts, make sure to include them in the project folder (including any fallback fonts for international characters, or bold/italic versions of fonts), and set as fallback font names.

Anti-aliasing

WebGL supports anti-aliasing on most (but not on all) combinations of browsers and GPUs. To use it, anti-aliasing must be enabled in the default Quality setting for the WebGL platform.

Reflection probes

Unity WebGL supports all reflection probesA rendering component that captures a spherical view of its surroundings in all directions, rather like a camera. The captured image is then stored as a Cubemap that can be used by objects with reflective materials. More info
See in Glossary
. Note: WebGL 1.0 doesn’t support Smooth realtime reflection probes.

WebGL 2.0 support

Unity includes support for the WebGL 2.0 API, which brings OpenGL ES 3.0-level rendering capabilities to the web.

By default, Unity WebGL builds support the WebGL 2.0 API. You can configure this in the WebGL Player settings > Other Settings panel by disabling the Automatic Graphics API property and adding the WebGL 1.0 API to your project.

Browsers with WebGL 2.0 support have the following advantages:

  • The content in the Standard Shader is of high quality.
  • Support for GPU Instancing and directional lightmap.
  • There’s no restrictions on indexing and loops in shader code
  • Better performance.

You can use SystemInfo.graphicsDeviceType at run time to determine whether the Unity instance is rendering with OpenGLES3 (WebGL2.0) or OpenGLES2 (WebGL1.0).

Additional resources:


  • Linear rendering for WebGL 2.0 added in 2017.2 NewIn20172
Cache behavior in WebGL
Audio in WebGL
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