WebGLRenderingContext: blendEquation() method
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Note: This feature is available in Web Workers.
The WebGLRenderingContext.blendEquation() method of the WebGL API is used to set both the RGB blend equation and alpha blend equation to a single equation.
The blend equation determines how a new pixel is combined with a pixel already in the WebGLFramebuffer.
Syntax
blendEquation(mode) Parameters
mode-
A
GLenumspecifying how source and destination colors are combined. Must be either:gl.FUNC_ADD: source + destination (default value)gl.FUNC_SUBTRACT: source - destinationgl.FUNC_REVERSE_SUBTRACT: destination - source
When using the
EXT_blend_minmaxextension:ext.MIN_EXT: Minimum of source and destinationext.MAX_EXT: Maximum of source and destination
When using a WebGL 2 context, the following values are available additionally:
gl.MIN: Minimum of source and destinationgl.MAX: Maximum of source and destination
Exceptions
If mode is not one of the three possible values, a gl.INVALID_ENUM error is thrown.
Return value
None (undefined).
Examples
To set the blend equation, use:
gl.blendEquation(gl.FUNC_ADD); gl.blendEquation(gl.FUNC_SUBTRACT); gl.blendEquation(gl.FUNC_REVERSE_SUBTRACT); To get the blend equations, query the BLEND_EQUATION, BLEND_EQUATION_RGB and BLEND_EQUATION_ALPHA constants which return gl.FUNC_ADD, gl.FUNC_SUBTRACT, gl.FUNC_REVERSE_SUBTRACT, or if the EXT_blend_minmax is enabled: ext.MIN_EXT or ext.MAX_EXT.
gl.getParameter(gl.BLEND_EQUATION_RGB) === gl.FUNC_ADD; // true gl.getParameter(gl.BLEND_EQUATION_ALPHA) === gl.FUNC_ADD; // true Specifications
| Specification |
|---|
| WebGL Specification # 5.14.3 |