Making a colour transparent?

[CopperCircle]

Hi I am trying to make a shader that will make a specific colour or range of colours transparent, I have looked at the alphatest shader and that discards "diffuse.w<0.5", I presume w is the alpha value, I cant find any info on how to access colour values? Is there a good site for learning the basic GLSL command set?

[Gandi]

diffuse.r / x

diffuse.g / y

diffuse.b / z

diffuse.a / w

 

hope you have your model in transparency world..

[CopperCircle]

Thats great thanks.