I want to blend two textures, each with specified opacity, follwing is my imaginary code. (no surprise it won't work)
<appearance>
<ImageTexture url="texture1.jpg" opacity="0.7"></ImageTexture>
<ImageTexture url="texture2.jpg" opacity="0.3"></ImageTexture>
</appearance>
Looks like it might have something to do with MultiTexture or BlendMode, but I haven't figure out how it works yet.
I just realize an appearance node can have both texture and material properties at the same time, so the following works perfectly fine to me.
<shape>
<sphere></sphere>
<appearance>
<ImageTexture url="texture1.jpg"></ImageTexture>
</appearance>
</shape>
<shape>
<sphere></sphere>
<appearance>
<material transparency="0.3"></material>
<ImageTexture url="texture2.jpg"></ImageTexture>
</appearance>
</shape>