Setting material/color alpha

Ok this should be obvious and trivial.

I just want to set the alpha for a color value.
I am just seriously deficiant in the basic flow of the material system, I can get access to everything i need, except the possiblity to setting the (w, or a) value for a Vector 4(or RGBA if you want).

The goal is to make a still detectable invisiblity effect, using the fresnel to define the edges.

Your material either needs to be translucent(to be able to set an opacity value), or you need to change the character’s material to that kind of a translucent material whenever needed.

Thank you. I was sure I was going crazy. Thats much better then specifiying alpha as part of the color parameters. Makes a lot more sense. And I roughly got the effect I was expecting. Thanks again.