Creating an Alpha Channel

If you are new to level design (on Q3A engines) then you will find out that for transparent textures you need a TGA file (instead of JPG) and an Alpha channel. So what is this Alpha channel all about?

The alpha channel defines what will be visible of an image and what not. White areas in the Alpha channel say that this place is visble. Black means they are not visible. You can of course have also gray areas. That will result in a kind of semi-transparency (very useful for glass shaders). So let's start. For this tutorial I used Photoshop CS2 but creating an Alpha is similar in the free Gimp image editing tool from what I remember.

For this tutorial I'm assuming that you have already an image with transparency. In this example the transparent layer has a effects in it (shadow, stroke line).

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