Is it possible to have (semi)transparent objects (i.e. a drinking glass) appear correctly when running a game?
Yes, you can create transparent or semitransparent objects by using the alpha layer of .tga or .png textures and hitting the ‘alpha’ button in the paint window while the faces are selected (don’t forget to hit ‘copy drawmode’ if you are mapping multiple faces and wanting them also transparent).
Unfortunately the Blender gameengine doesn’t sort transparent faces according to their z-buffer depth - so it can happen that a transparent object wihch is supposed to be behind of another one appears to be in front. I hope this will be fixed.
I think You can use simple JPG’s too. Texture Your Object and set the Faces to Alpha. Now make an one Frame IPO on the R, G, B and A Channels. Set the RGB Channels to 1.0 and the A Channel to the Transparency Value (Maybe 0.5) and give Your Object an IPO Actuator. If You make this Setting at Frame 1 of the IPO You don’t need to ‘fire’ the Actuator.
I’ve never tested that. But it could work
Doc
you can also use a rgba jpeg, but the easiest way is to render it from blender itself. (most programs don’t support it (if any others do at all))
A lot of programs support alpha channels. Most of the advanced ones do, like Gimp or Photoshop. I’m sure there’s plenty others.
Pooba
Zero was refering to - CMYK jpegs - you can use the black channel to be a alpha channel. Gimp doesn’t have CMYK support (yet - but it’s on its way).