   Bloom and Transparent Geometry
  Hi,I use a group of semi transparent cloud sprites to give my clouds a volume look.  I also bloom my sun but am having trouble with the bloom for the clouds.  The bloom works well for the cloud edges, but for areas in the interior where the cloud density is low (mostly transparent) the bloom effect is not showing because the cloud is occluding it (even though it is barely visible).  What is the solution to this?  It seems like when I draw the sun to the bloom texture, I need an additional mask of partially transparent objects to weaken the sun intensity through partially transparent objects.   
  I've solved this by giving a little enum to my materials that controls how alpha is actually used.Basically, alpha is either completely ignored, used for translucency, used for glow, or both.You can make situational decisions when you come to render something as to whether to allow dest-z writes, alpha testing etc. With a bit of fiddling, you can make all the cases work together, and I've got exactly what you're desribing in the form of a transparent neon sign that also glows.If you have a lot of glow in your destination already, you can subtract a bit from your cloud by drawing with subtractive and only enable the "A" colour write mask, then draw it again as you like into the RGB channels.   