how to use the alpha channel of an image as a material's opacity map?

[fael097]

I saved an image with a transparent background as multiple formats that support alpha channels, such as png, tga, etc and still I haven't found a way to use the alpha channel as opacity map.

how do i do this?

thanks

[CAMedeck · Accepted solution]

Assuming you are using a Bitmap node in the material editor, look under the Bitmap Parameters rollout.  If your image does indeed have an alpha channel, you'll be able to click the radio buttons to set Mono Channel Output to Alpha and RGB Channel Output to Alpha as Gray.  With both of these selected, your bitmap preview should just display the alpha channel of your image.  This can be plugged into the Opacity slot of your material.

[domo.spaji · Accepted solution]

Just Mono Channel Output to Alpha.

RGB Channel has no effect on opacity.

+ can use same map for eg. diffuze and opacity.

[CAMedeck]

I have had occasional issues with plugging a Bitmap into Opacity and Diffuse.  Most times it works (with Mono Channel to Alpha enabled) but the few times it doesn't come out as expected, I've cloned the Bitmap and set the Alpha as Gray for just the Opacity.  It is worth trying the first method.

[fael097]

thanks guys, it worked perfectly!