Revision 966059 of WebGLRenderingContext

<div>{{APIRef("WebGL")}}</div>

<p>The <strong>WebGLRenderingContext</strong> interface provides the OpenGL ES 2.0 rendering context for the drawing surface of an HTML {{HTMLElement("canvas")}} element.</p>

<p>To get an object of this interface, call {{domxref("HTMLCanvasElement.getContext()", "getContext()")}} on a <code>&lt;canvas&gt;</code> element, supplying "webgl" as the argument:</p>

<pre class="brush: js">
var canvas = document.getElementById('myCanvas');
var gl = canvas.getContext('webgl');
</pre>

<p>Once you have the WebGL rendering context for a canvas, you can render within it.</p>

<p>The <a href="/en-US/docs/Web/API/WebGL_API/Tutorial" title="WebGL tutorial">WebGL tutorial</a> has more information, examples, and resources on how to get started with WebGL.</p>

<h2 id="Constants">Constants</h2>

<p>See the <a href="/en-US/docs/Web/API/WebGL_API/Constants">WebGL constants</a> page.</p>

<h2 id="Context_information">Context information</h2>

<p>The following attributes and methods provide read-only information about the context:</p>

<dl>
 <dt>{{domxref("WebGLRenderingContext.canvas")}}</dt>
 <dd>A read-only back-reference to the {{domxref("HTMLCanvasElement")}}. Might be {{jsxref("null")}} if it is not associated with a {{HTMLElement("canvas")}} element.</dd>
 <dt>{{domxref("WebGLRenderingContext.drawingBufferWidth")}}</dt>
 <dd>The read-only width of the current drawing buffer. Should match the width of the canvas element associated with this context.</dd>
 <dt>{{domxref("WebGLRenderingContext.drawingBufferHeight")}}</dt>
 <dd>The read-only height of the current drawing buffer. Should match the height of the canvas element associated with this context.</dd>
 <dt>{{domxref("WebGLRenderingContext.getContextAttributes()")}}</dt>
 <dd>Returns a <code>WebGLContextAttributes</code> object that contains the actual context parameters. Might return {{jsxref("null")}}, if the context is lost.</dd>
 <dt>{{domxref("WebGLRenderingContext.isContextLost()")}}</dt>
 <dd>Returns <code>true</code> if the context is lost, otherwise returns <code>false</code>.</dd>
</dl>

<h2 id="Viewing_and_clipping">Viewing and clipping</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.scissor()")}}</dt>
 <dd>Defines the scissor box.</dd>
 <dt>{{domxref("WebGLRenderingContext.viewport()")}}</dt>
 <dd>Sets the viewport.</dd>
</dl>

<h2 id="State_information">State information</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.activeTexture()")}}</dt>
 <dd>Selects the active texture unit.</dd>
 <dt>{{domxref("WebGLRenderingContext.blendColor()")}}</dt>
 <dd>Sets the source and destination blending factors.</dd>
 <dt>{{domxref("WebGLRenderingContext.blendEquation()")}}</dt>
 <dd>Sets both the RGB blend equation and alpha blend equation to a single equation.</dd>
 <dt>{{domxref("WebGLRenderingContext.blendEquationSeparate()")}}</dt>
 <dd>Sets the RGB blend equation and alpha blend equation separately.</dd>
 <dt>{{domxref("WebGLRenderingContext.blendFunc()")}}</dt>
 <dd>Defines which function is used for blending pixel arithmetic.</dd>
 <dt>{{domxref("WebGLRenderingContext.blendFuncSeparate()")}}</dt>
 <dd>Defines which function is used for blending pixel arithmetic for RGB and alpha components separately.</dd>
 <dt>{{domxref("WebGLRenderingContext.clearColor()")}}</dt>
 <dd>Specifies the color values used when clearing color buffers.</dd>
 <dt>{{domxref("WebGLRenderingContext.clearDepth()")}}</dt>
 <dd>Specifies the depth value used when clearing the depth buffer.</dd>
 <dt>{{domxref("WebGLRenderingContext.clearStencil()")}}</dt>
 <dd>Specifies the stencil value used when clearing the stencil buffer.</dd>
 <dt>{{domxref("WebGLRenderingContext.colorMask()")}}</dt>
 <dd>Sets which color components to enable or to disable when drawing or rendering to a {{domxref("WebGLFramebuffer")}}.</dd>
 <dt>{{domxref("WebGLRenderingContext.cullFace()")}}</dt>
 <dd>Specifies whether or not front- and/or back-facing polygons can be culled.</dd>
 <dt>{{domxref("WebGLRenderingContext.depthFunc()")}}</dt>
 <dd>Specifies a function that compares incoming pixel depth to the current depth buffer value.</dd>
 <dt>{{domxref("WebGLRenderingContext.depthMask()")}}</dt>
 <dd>Sets whether writing into the depth buffer is enabled or disabled.</dd>
 <dt>{{domxref("WebGLRenderingContext.depthRange()")}}</dt>
 <dd>Specifies the depth range mapping from normalized device coordinates to window or viewport coordinates.</dd>
 <dt>{{domxref("WebGLRenderingContext.disable()")}}</dt>
 <dd>Disables specific WebGL capabilities for this context.</dd>
 <dt>{{domxref("WebGLRenderingContext.enable()")}}</dt>
 <dd>Enables specific WebGL capabilities for this context.</dd>
 <dt>{{domxref("WebGLRenderingContext.frontFace()")}}</dt>
 <dd>Specifies whether polygons are front- or back-facing by setting a winding orientation.</dd>
 <dt>{{domxref("WebGLRenderingContext.getParameter()")}}</dt>
 <dd>Returns a value for the passed parameter name.</dd>
 <dt>{{domxref("WebGLRenderingContext.getError()")}}</dt>
 <dd>Returns error information.</dd>
 <dt>{{domxref("WebGLRenderingContext.hint()")}}</dt>
 <dd>Specifies hints for certain behaviors. The interpretation of these hints depend on the implementation.</dd>
 <dt>{{domxref("WebGLRenderingContext.isEnabled()")}}</dt>
 <dd>Tests whether a specific WebGL capability is enabled or not for this context.</dd>
 <dt>{{domxref("WebGLRenderingContext.lineWidth()")}}</dt>
 <dd>Sets the line width of rasterized lines.</dd>
 <dt>{{domxref("WebGLRenderingContext.pixelStorei()")}}</dt>
 <dd>Specifies the pixel storage modes</dd>
 <dt>{{domxref("WebGLRenderingContext.polygonOffset()")}}</dt>
 <dd>Specifies the scale factors and units to calculate depth values.</dd>
 <dt>{{domxref("WebGLRenderingContext.sampleCoverage()")}}</dt>
 <dd>Specifies multi-sample coverage parameters for anti-aliasing effects.</dd>
 <dt>{{domxref("WebGLRenderingContext.stencilFunc()")}}</dt>
 <dd>Sets the both front and back function and reference value for stencil testing.</dd>
 <dt>{{domxref("WebGLRenderingContext.stencilFuncSeparate()")}}</dt>
 <dd>Sets the front and/or back function and reference value for stencil testing.</dd>
 <dt>{{domxref("WebGLRenderingContext.stencilMask()")}}</dt>
 <dd>Controls enabling and disabling of both the front and back writing of individual bits in the stencil planes.</dd>
 <dt>{{domxref("WebGLRenderingContext.stencilMaskSeparate()")}}</dt>
 <dd>Controls enabling and disabling of front and/or back writing of individual bits in the stencil planes.</dd>
 <dt>{{domxref("WebGLRenderingContext.stencilOp()")}}</dt>
 <dd>Sets both the front and back-facing stencil test actions.</dd>
 <dt>{{domxref("WebGLRenderingContext.stencilOpSeparate()")}}</dt>
 <dd>Sets the front and/or back-facing stencil test actions.</dd>
</dl>

<h2 id="Buffers">Buffers</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.bindBuffer()")}}</dt>
 <dd>Binds a <code>WebGLBuffer</code> object to a given target.</dd>
 <dt>{{domxref("WebGLRenderingContext.bufferData()")}}</dt>
 <dd>Updates buffer data.</dd>
 <dt>{{domxref("WebGLRenderingContext.bufferSubData()")}}</dt>
 <dd>Updates buffer data starting at a passed offset.</dd>
 <dt>{{domxref("WebGLRenderingContext.createBuffer()")}}</dt>
 <dd>Creates a <code>WebGLBuffer</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.deleteBuffer()")}}</dt>
 <dd>Deletes a <code>WebGLBuffer</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.getBufferParameter()")}}</dt>
 <dd>Returns information about the buffer.</dd>
 <dt>{{domxref("WebGLRenderingContext.isBuffer()")}}</dt>
 <dd>Returns a Boolean indicating if the passed buffer is valid.</dd>
</dl>

<h2 id="Framebuffers">Framebuffers</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.bindFramebuffer()")}}</dt>
 <dd>Binds a <code>WebGLFrameBuffer</code> object to a given target.</dd>
 <dt>{{domxref("WebGLRenderingContext.checkFramebufferStatus()")}}</dt>
 <dd>Returns the status of the framebuffer.</dd>
 <dt>{{domxref("WebGLRenderingContext.createFramebuffer()")}}</dt>
 <dd>Creates a <code>WebGLFrameBuffer</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.deleteFramebuffer()")}}</dt>
 <dd>Deletes a <code>WebGLFrameBuffer</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.framebufferRenderbuffer()")}}</dt>
 <dd>Attaches a <code>WebGLRenderingBuffer</code> object to a <code>WebGLFrameBuffer</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.framebufferTexture2D()")}}</dt>
 <dd>Attaches a textures image to a <code>WebGLFrameBuffer</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.getFramebufferAttachmentParameter()")}}</dt>
 <dd>Returns information about the framebuffer.</dd>
 <dt>{{domxref("WebGLRenderingContext.isFramebuffer()")}}</dt>
 <dd>Returns a Boolean indicating if the passed <code>WebGLFrameBuffer</code> object is valid.</dd>
 <dt>{{domxref("WebGLRenderingContext.readPixels()")}}</dt>
 <dd>Reads a block of pixels from the <code>WebGLFrameBuffer</code>.</dd>
</dl>

<h2 id="Renderbuffers">Renderbuffers</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.bindRenderbuffer()")}}</dt>
 <dd>Binds a <code>WebGLRenderBuffer</code> object to a given target.</dd>
 <dt>{{domxref("WebGLRenderingContext.createRenderbuffer()")}}</dt>
 <dd>Creates a <code>WebGLRenderBuffer</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.deleteRenderbuffer()")}}</dt>
 <dd>Deletes a <code>WebGLRenderBuffer</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.getRenderbufferParameter()")}}</dt>
 <dd>Returns information about the renderbuffer.</dd>
 <dt>{{domxref("WebGLRenderingContext.isRenderbuffer()")}}</dt>
 <dd>Returns a Boolean indicating if the passed <code>WebGLRenderingBuffer</code> is valid.</dd>
 <dt>{{domxref("WebGLRenderingContext.renderbufferStorage()")}}</dt>
 <dd>Creates a renderbuffer data store.</dd>
</dl>

<h2 id="Textures">Textures</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.bindTexture()")}}</dt>
 <dd>Binds a <code>WebGLTexture</code> object to a given target.</dd>
 <dt>{{domxref("WebGLRenderingContext.compressedTexImage2D()")}}</dt>
 <dd>Specifies a 2D texture image in a compressed format.</dd>
 <dt>{{domxref("WebGLRenderingContext.compressedTexSubImage2D()")}}</dt>
 <dd>Specifies a 2D texture sub-image in a compressed format.</dd>
 <dt>{{domxref("WebGLRenderingContext.copyTexImage2D()")}}</dt>
 <dd>Copies a 2D texture image.</dd>
 <dt>{{domxref("WebGLRenderingContext.copyTexSubImage2D()")}}</dt>
 <dd>Copies a 2D texture sub-image.</dd>
 <dt>{{domxref("WebGLRenderingContext.createTexture()")}}</dt>
 <dd>Creates a <code>WebGLTexture</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.deleteTexture()")}}</dt>
 <dd>Deletes a <code>WebGLTexture</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.generateMipmap()")}}</dt>
 <dd>Generates a set of mipmaps for a <code>WebGLTexture</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.getTexParameter()")}}</dt>
 <dd>Returns information about the texture.</dd>
 <dt>{{domxref("WebGLRenderingContext.isTexture()")}}</dt>
 <dd>Returns a Boolean indicating if the passed <code>WebGLTexture</code> is valid.</dd>
 <dt>{{domxref("WebGLRenderingContext.texImage2D()")}}</dt>
 <dd>Specifies a 2D texture image.</dd>
 <dt>{{domxref("WebGLRenderingContext.texSubImage2D()")}}</dt>
 <dd>Updates a sub-rectangle of the current <code>WebGLTexture</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.texParameterf()")}}</dt>
 <dd>Sets texture parameters.</dd>
 <dt>{{domxref("WebGLRenderingContext.texParameteri()")}}</dt>
 <dd>Sets texture parameters.</dd>
</dl>

<h2 id="Programs_and_shaders">Programs and shaders</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.attachShader()")}}</dt>
 <dd>Attaches a <code>WebGLShader</code> to a <code>WebGLProgram</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.bindAttribLocation()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.compileShader()")}}</dt>
 <dd>Compiles a <code>WebGLShader</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.createProgram()")}}</dt>
 <dd>Creates a <code>WebGLProgram</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.createShader()")}}</dt>
 <dd>Creates a <code>WebGLShader</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.deleteProgram()")}}</dt>
 <dd>Deletes a <code>WebGLProgram</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.deleteShader()")}}</dt>
 <dd>Deletes a <code>WebGLShader</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.detachShader()")}}</dt>
 <dd>Detaches a <code>WebGLShader</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.getAttachedShaders()")}}</dt>
 <dd>Returns a list of <code>WebGLShader</code> objects attached to a <code>WebGLProgram</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.getProgramParameter()")}}</dt>
 <dd>Returns information about the program.</dd>
 <dt>{{domxref("WebGLRenderingContext.getProgramInfoLog()")}}</dt>
 <dd>Returns the information log for a <code>WebGLProgram</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.getShaderParameter()")}}</dt>
 <dd>Returns information about the shader.</dd>
 <dt>{{domxref("WebGLRenderingContext.getShaderPrecisionFormat()")}}</dt>
 <dd>Returns a <code>WebGLShaderPrecisionFormat</code> object describing the precision for the numeric format of the shader.</dd>
 <dt>{{domxref("WebGLRenderingContext.getShaderInfoLog()")}}</dt>
 <dd>Returns the information log for a <code>WebGLShader</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.getShaderSource()")}}</dt>
 <dd>Returns the source code of a <code>WebGLShader</code> as a string.</dd>
 <dt>{{domxref("WebGLRenderingContext.isProgram()")}}</dt>
 <dd>Returns a Boolean indicating if the passed <code>WebGLProgram</code> is valid.</dd>
 <dt>{{domxref("WebGLRenderingContext.isShader()")}}</dt>
 <dd>Returns a Boolean indicating if the passed <code>WebGLShader</code> is valid.</dd>
 <dt>{{domxref("WebGLRenderingContext.linkProgram()")}}</dt>
 <dd>Links the passed <code>WebGLProgram</code> object.</dd>
 <dt>{{domxref("WebGLRenderingContext.shaderSource()")}}</dt>
 <dd>Sets the source code in a <code>WebGLShader</code>.</dd>
 <dt>{{domxref("WebGLRenderingContext.useProgram()")}}</dt>
 <dd>Uses the specified <code>WebGLProgram</code> as part the current rendering state.</dd>
 <dt>{{domxref("WebGLRenderingContext.validateProgram()")}}</dt>
 <dd>Validates a <code>WebGLProgram</code>.</dd>
</dl>

<h2 id="Uniforms_and_attributes">Uniforms and attributes</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.disableVertexAttribArray()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.enableVertexAttribArray()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.getActiveAttrib()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.getActiveUniform()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.getAttribLocation()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.getUniform()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.getVertexAttrib()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.getVertexAttribOffset()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.disableVertexAttribArray()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.uniform()", "WebGLRenderingContext.uniform[1234][fi][v]()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.uniformMatrix()", "WebGLRenderingContext.uniformMatrix[1234][fv]()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.vertexAttrib()", "WebGLRenderingContext.vertexAttrib[1234][fi][v]()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.vertexAttribPointer()")}}</dt>
 <dd>...</dd>
</dl>

<h2 id="Drawing_buffers">Drawing buffers</h2>

<dl>
 <dt>{{domxref("WebGLRenderingContext.clear()")}}</dt>
 <dd>Clears specified buffers to preset values.</dd>
 <dt>{{domxref("WebGLRenderingContext.drawArrays()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.drawElements()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.finish()")}}</dt>
 <dd>...</dd>
 <dt>{{domxref("WebGLRenderingContext.flush()")}}</dt>
 <dd>...</dd>
</dl>

<h2 id="Working_with_extensions">Working with extensions</h2>

<p>These methods manage WebGL extensions:</p>

<dl>
 <dt>{{domxref("WebGLRenderingContext.getSupportedExtensions()")}}</dt>
 <dd>Returns an {{jsxref("Array")}} of {{domxref("DOMString")}} elements with all the supported WebGL extensions.</dd>
 <dt>{{domxref("WebGLRenderingContext.getExtension()")}}</dt>
 <dd>Returns an extension object.</dd>
</dl>

<h2 id="Examples">Examples</h2>

<h3 id="WebGL_context_feature_detection">WebGL context feature detection</h3>

<p>{{page("/en-US/Learn/WebGL/By_example/Detect_WebGL", "summary")}}</p>

<p>{{page("/en-US/Learn/WebGL/By_example/Detect_WebGL", "detect-webgl-source")}}</p>

<p>{{EmbedLiveSample("detect-webgl-source", 660,150 ,"" , "Learn/WebGL/By_example/Detect_WebGL")}}</p>

<h3 id="Effect_of_canvas_size_on_rendering_with_WebGL">Effect of canvas size on rendering with WebGL</h3>

<p>{{page("/en-US/Learn/WebGL/By_example/Canvas_size_and_WebGL", "canvas-size-and-webgl-intro")}}</p>

<p>{{page("/en-US/Learn/WebGL/By_example/Canvas_size_and_WebGL", "canvas-size-and-webgl-source")}}</p>

<p>{{EmbedLiveSample("canvas-size-and-webgl-source", 660,180 ,"" , "Learn/WebGL/By_example/Canvas_size_and_WebGL")}}</p>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('WebGL', "#5.14", "WebGLRenderingContext")}}</td>
   <td>{{Spec2('WebGL')}}</td>
   <td>Initial definition</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<p>{{CompatibilityTable}}</p>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Edge</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatChrome("9")}}</td>
   <td>20</td>
   <td>{{CompatGeckoDesktop("2.0")}}</td>
   <td>{{CompatIE("11")}}</td>
   <td>{{CompatOpera("12")}}</td>
   <td>{{CompatSafari("5.1")}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Chrome for Android</th>
   <th>Edge</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatUnknown}}</td>
   <td>25</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatGeckoMobile("2.0")}}</td>
   <td>1.0</td>
   <td>{{CompatUnknown}}</td>
   <td>12</td>
   <td>8.0</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="See_also">See also</h2>

<ul>
 <li>{{domxref("HTMLCanvasElement")}}</li>
</ul>