Transparency and depth

[Reza Ghassemi <reza robin1 gmail com>]

Hi,

Currently with clutter/cogl if you have partially transparent actors and you are using depth testing and the actors are at different depths and overlapping,  for the scene to look correct,  you must order the actors in the scene so that they end up drawing back to front.  This is problematic when the actors are being animated and changing their overlapping.  

This is quite inconvenient and a management complication  to high level app developers who would rather just leave the actors in the order they added them.  Other systems like webkit/html5 seem to handle this.   Are there any ideas out there on how to approach this or potentially add an optional sorting algorithm based on depth to clutter's scene rendering system?

Thanks,

Reza