Can you tell us a bit about the future plan for the blending? It's such a nice feature and I really would like to (mis)use it at some point. I know that Oolite is in feature freeze and it's all future music, but it would be good to know a bit more (e.g. own render pass, disable CULL_FACE, control settings in effectdata.plist, etc).
After all, anticipation is already half the fun.-)
To be honest, I don't really have a future plan about blending. The objective of the exercise was to enable transparency in effects and that's it. I don't know if there is a point in trying to enable transparency on non-effect entities (maybe that would not be too difficult), but anything else will have to overcome two somewhat important issues:
1. I am not really that familiar with the game's rendering system. Any change like those you mentioned would require some additional studying and digging into the lowest-level internals of the code base before I even consider attempting it.
2. Oolite has a really robust internal system for checking its render state while drawing a frame or parts of it. If it detects an inconsistent or unexpected change of rendering parameters at any time, it will a) report the state it found and the state it was expecting to find and b) switch OpenGL settings to match the expected state. Therefore, before attempting anything low-level, this will have to be tamed somehow and that would add even more effort. Not impossible (we did manage to trick the system with effects transparency after all), but certainly no trivial task. And maybe we should not adopt a habit of applying hacks like I did either. The transparency was a one-off; if more is to be done, it should probably be handled properly by setting up the system to know what to expect..
Still, if anyone feels like diving in and coming up with a patch to improve rendering even further, I would certainly not object.