var CONST = require('../const'); 
var isEnabled = false ; 
var currentBlend = null ; 
var currentBlendEquation = null ; 
var currentBlendSrc = null ; 
var currentBlendDst = null ; 
var currentBlendEquationAlpha = null ; 
var currentBlendSrcAlpha = null ; 
var currentBlendDstAlpha = null ; 
var currentPremultipliedAlpha = null ; 
var SetBlendMode = function (state, blend, blendEquation, blendSrc, blendDst, blendEquationAlpha, blendSrcAlpha, blendDstAlpha, premultipliedAlpha){ 
var gl = state.gl; 
if (blend === CONST.BLEND_TYPE.NONE) { 
gl.disable(gl.BLEND); 
isEnabled = false ; 
} 
 else if (!isEnabled) { 
gl.enable(gl.BLEND); 
isEnabled = true ; 
} 
if (blend !== CONST.BLEND_TYPE.CUSTOM) { 
if (blend !== currentBlend || premultipliedAlpha !== currentPremultipliedAlpha) { 
if (blend === CONST.BLEND_TYPE.NORMAL) { 
if (premultipliedAlpha) { 
gl.blendEquationSeparate(gl.FUNC_ADD, gl.FUNC_ADD); 
gl.blendFuncSeparate(gl.ONE, gl.ONE_MINUS_SRC_ALPHA, gl.ONE, gl.ONE_MINUS_SRC_ALPHA); 
} 
 else { 
gl.blendEquationSeparate(gl.FUNC_ADD, gl.FUNC_ADD); 
gl.blendFuncSeparate(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA, gl.ONE, gl.ONE_MINUS_SRC_ALPHA); 
} 
} 
if (blend === CONST.BLEND_TYPE.ADD) { 
if (premultipliedAlpha) { 
gl.blendEquationSeparate(gl.FUNC_ADD, gl.FUNC_ADD); 
gl.blendFuncSeparate(gl.ONE, gl.ONE, gl.ONE, gl.ONE); 
} 
 else { 
gl.blendEquation(gl.FUNC_ADD); 
gl.blendFunc(gl.SRC_ALPHA, gl.ONE); 
} 
} 
} 
currentBlendEquation = null ; 
currentBlendSrc = null ; 
currentBlendDst = null ; 
currentBlendEquationAlpha = null ; 
currentBlendSrcAlpha = null ; 
currentBlendDstAlpha = null ; 
} 
 else { 
blendEquationAlpha = blendEquationAlpha || blendEquation; 
blendSrcAlpha = blendSrcAlpha || blendSrc; 
blendDstAlpha = blendDstAlpha || blendDst; 
if (blendEquation !== currentBlendEquation || blendEquationAlpha !== currentBlendEquationAlpha) { 
gl.blendEquationSeparate(blendEquation, blendEquationAlpha); 
currentBlendEquation = blendEquation; 
currentBlendEquationAlpha = blendEquationAlpha; 
} 
if (blendSrc !== currentBlendSrc || blendDst !== currentBlendDst || blendSrcAlpha !== currentBlendSrcAlpha || blendDstAlpha !== currentBlendDstAlpha) { 
gl.blendFuncSeparate(blendSrc, blendDst, blendSrcAlpha, blendDstAlpha); 
currentBlendSrc = blendSrc; 
currentBlendDst = blendDst; 
currentBlendSrcAlpha = blendSrcAlpha; 
currentBlendDstAlpha = blendDstAlpha; 
} 
} 
currentBlend = blend; 
currentPremultipliedAlpha = premultipliedAlpha; 
} 
; 
module.exports = SetBlendMode;