WebGLRenderingContext.blendFunc()

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WebGLRenderingContext.blendFunc() 方法在 WebGL API defines which function is used for blending pixel arithmetic.

句法

void gl.blendFunc(sfactor, dfactor);

参数

sfactor: A GLenum specifying a multiplier for the source blending factors. The default value is gl.ONE . For possible values, see below.
dfactor: A GLenum specifying a multiplier for the destination blending factors. The default value is gl.ZERO . For possible values, see below.

返回值

None.

异常

若 sfactor or dfactor is not one of the listed possible values, a gl.INVALID_ENUM error is thrown.
If a constant color and a constant alpha value are used together as source and destination factors, a gl.INVALID_ENUM error is thrown.

常量

The following constants can be used for sfactor and dfactor .

The formula for the blending color can be described like this: color(RGBA) = (sourceColor * sfactor ) + (destinationColor * dfactor ). The RBGA values are between 0 and 1.

常量	Factor	描述
`gl.ZERO`	0,0,0,0	Multiplies all colors by 0.
`gl.ONE`	1,1,1,1	Multiplies all colors by 1.
`gl.SRC_COLOR`	R _S , G _S , B _S , A _S	Multiplies all colors by the source colors.
`gl.ONE_MINUS_SRC_COLOR`	1-R _S , 1-G _S , 1-B _S , 1-A _S	Multiplies all colors by 1 minus each source color.
`gl.DST_COLOR`	R _D , G _D , B _D , A _D	Multiplies all colors by the destination color.
`gl.ONE_MINUS_DST_COLOR`	1-R _D , 1-G _D , 1-B _D , 1-A _D	Multiplies all colors by 1 minus each destination color.
`gl.SRC_ALPHA`	A _S , A _S , A _S , A _S	Multiplies all colors by the source alpha value.
`gl.ONE_MINUS_SRC_ALPHA`	1-A _S , 1-A _S , 1-A _S , 1-A _S	Multiplies all colors by 1 minus the source alpha value.
`gl.DST_ALPHA`	A _D , A _D , A _D , A _D	Multiplies all colors by the destination alpha value.
`gl.ONE_MINUS_DST_ALPHA`	1-A _D , 1-A _D , 1-A _D , 1-A _D	Multiplies all colors by 1 minus the destination alpha value.
`gl.CONSTANT_COLOR`	R _C , G _C , B _C , A _C	Multiplies all colors by a constant color.
`gl.ONE_MINUS_CONSTANT_COLOR`	1-R _C , 1-G _C , 1-B _C , 1-A _C	Multiplies all colors by 1 minus a constant color.
`gl.CONSTANT_ALPHA`	A _C , A _C , A _C , A _C	Multiplies all colors by a constant alpha value.
`gl.ONE_MINUS_CONSTANT_ALPHA`	1-A _C , 1-A _C , 1-A _C , 1-A _C	Multiplies all colors by 1 minus a constant alpha value.
`gl.SRC_ALPHA_SATURATE`	min(A _S , 1 - A _D ), min(A _S , 1 - A _D ), min(A _S , 1 - A _D ), 1	Multiplies the RGB colors by the smaller of either the source alpha value or the value of 1 minus the destination alpha value. The alpha value is multiplied by 1.

范例

To use the blend function, you first have to activate blending with WebGLRenderingContext.enable() with the argument gl.BLEND .

gl.enable(gl.BLEND);
gl.blendFunc(gl.SRC_COLOR, gl.DST_COLOR);

To get the current blend function, query the BLEND_SRC_RGB , BLEND_SRC_ALPHA , BLEND_DST_RGB ，和 BLEND_DST_ALPHA constants which return one of the blend function constants.

gl.enable(gl.BLEND);
gl.blendFunc(gl.SRC_COLOR, gl.DST_COLOR);
gl.getParameter(gl.BLEND_SRC_RGB) == gl.SRC_COLOR;
// true

规范

规范	状态	注释
WebGL 1.0 The definition of 'blendFunc' in that specification.	推荐	初始定义。 In WebGL, constant color and constant alpha cannot be used together as source and destination factors in the blend function. See section 6.13. of the specification.
OpenGL ES 2.0 The definition of 'glBlendFunc' in that specification.	标准	Man page of the OpenGL API.

浏览器兼容性

更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`blendFunc`	Chrome 9	Edge 12	Firefox 4	IE 11	Opera 12	Safari 5.1	WebView Android Yes	Chrome Android 25	Firefox Android Yes	Opera Android 12	Safari iOS 8	Samsung Internet Android 1.5

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