OK, I have my fx_wake.bmp file with the coloured and transparent bits just the way I want them. But when it displays as an effect in FS2004, there is a "bordering" effect. Every boundary between a transparent and opaque colour has a medium-grey boundary around it. These boundaries stay a constant apparent thickness, so from a long way away, they dominate the entire texture, making it look almost completely medium-grey. If this is not entirely clear I can paste in some screen caps.
I am using DXTBmp to create these files. They are all 128 X 128 pixels so there is no green-bleed issue. This happens irrespective of which format I save the files in. Is there some other product to create my transparent textures? Or some other technique?
Steve from Mudgee.