Blending

[Morozoov8]

Hello!
I have some question about blending in OSG.JS glTF loader.
I write osg loader and use this for base.
In OSG.JS blendFunction is uses:
this._defaultBlendFunc = new BlendFunc(); this._transparentBlendFunc = new BlendFunc('SRC_ALPHA', 'ONE_MINUS_SRC_ALPHA');
You can find it here (178-179):

made the same but nothing happened. I can't see windows or brakeLights in model ZIS-101-3. For blending I get alpha-channel from baseColor value, in model zis-101 alpha-channel is zero. Is it normal?
What blending in osg.js need except blendFunction?