title | short-title | slug | page-type | browser-compat |
---|---|---|---|---|
WebGLRenderingContext: blendEquation() method |
blendEquation() |
Web/API/WebGLRenderingContext/blendEquation |
web-api-instance-method |
api.WebGLRenderingContext.blendEquation |
{{APIRef("WebGL")}}
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 {{domxref("WebGLFramebuffer")}}.
blendEquation(mode)
-
mode
-
: A {{domxref("WebGL_API/Types", "GLenum")}} specifying 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 {{domxref("EXT_blend_minmax")}} extension:
ext.MIN_EXT
: Minimum of source and destinationext.MAX_EXT
: Maximum of source and destination
When using a {{domxref("WebGL2RenderingContext", "WebGL 2 context", "", 1)}}, the following values are available additionally:
gl.MIN
: Minimum of source and destinationgl.MAX
: Maximum of source and destination
-
If mode is not one of the three possible values, a
gl.INVALID_ENUM
error is thrown.
None ({{jsxref("undefined")}}).
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 {{domxref("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}}
{{Compat}}
- {{domxref("WebGLRenderingContext.blendColor()")}}
- {{domxref("WebGLRenderingContext.blendFunc()")}}
- {{domxref("EXT_blend_minmax")}}