Alpha mapping in Cycles

Hello,

Alpha mapping ??

This was actually quite easy when it is done in Blender Internal Render.
Scale marking and transparent texture were easy to done in Internal render but little bit tricky when it comes to the cycles.
And for this little bit knowledge in Nodes is required.

In internal render when I do UV texture I create an another material identical to the original material and do the UV texture with the second material.
Otherwise texture will come on entire object.

While doing UV texture in cycles  I followed the same procedure and I used mix shader to combine both the material shader.
But  when I was doing transparent texture like of ruler texture or marking on screw gauge that time the method didn't work. Either the UV texture was blank or it showed mixture of both the material.

I tried many different ways to get it right like adding invert node or black white but it didn't work.

In internal render this problem is solved by using alpha or controlling the alpha value of the image texture.

In cycles if we want to do the same than alpha value of the image has to be given to the factor of mix shader in node setup.

 

This is the node setup for the texture I had done for screw gauge object.

In mix shader, one shader is image texture and the other shader is diffuse shader, and the alpha of the image texture is connected factor in mix shader.

 Screw gauge render files, other material and lighting done by Pooja Bhawar.