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I'm trying to use the alpha channel of an image as my emission map in cycles, but for some reason, the render just renders the alpha and not the colour of the texture, even when I plug only the colour directly into the diffuse BSDF and the diffuse directly into the output node. I'm actually trying to mix the diffuse with an emission shader to make certain parts of the texture always illuminated. However, with this setup, the alpha channel renders on top of itself and looks pretty much the same as when just plugging the alpha channel directly into the output via a diffuse shader.

Note that my image is in TGA format, after I originally had issues with using alpha on a PSD (which would always render white).

Here is my node setup: enter image description here

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    $\begingroup$ Could you post some screenshots of your render? I think you need to connect the color output of your image texture directly into the color input socket of the Emission and Diffuse node, and the Alpha socket directly factor socket of the Shader Mix node $\endgroup$ – Duarte Farrajota Ramos Mar 10 '16 at 3:04
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    $\begingroup$ Note that using an Add shader as PGmath suggests will make emissive parts of the mesh both emit and reflect light. If you only want emission in those areas, then it should be as simple as plugging the alpha channel into the mix factor (as described above) $\endgroup$ – gandalf3 Mar 10 '16 at 3:33
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In order to do what you are you describing, you need to make a couple changes to your node setup.

  • Change the Mix Shader to an Add Shader.
  • Unplug the texture color from the multiply node and plug the multiply node into the Strength instead of the Color of the Emission shader. You can now use the multiply node to adjust the strength of the emissive parts of the material.
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