The _render_stages and _render_ff_stages cannot simply be copied, because they contain pointer references to the previous TextureAttrib. Never copy them, and always mark _sort_seq as stale.
This fixes a test failure in replace_texture.
This is done by:
* Not considering the texture pointer when looking up a generated shader, only type
* Not requiring different shaders based on RescaleNormalAttrib
* Not looking at AlphaTestAttrib unless it is going to be relevant
This should dramatically reduce the number of shaders that are being generated for many scenes, especially since the only thing that differs from object to object is often just the texture.
These changes are also necessary to make b781995ef1 more usable, since prepare_scene may see a slightly different state than is encountered at render time due to code in CullResult adding in an AlphaTestAttrib or RescaleNormalAttrib.
rdb
Sam Edwards
tobspr
David Rose
Josh Yelon