SL-20606: Reuse vertex buffer between preview renders. Fix preview sometimes zoomed in too much. Miscellaneous cleanup

DRTVWR-559
SL-19524
SL-19513

Jonathan Goodman authored 2 years ago and David Parks committed 2 years ago

First pass of Screen Space Reflections

Approved-by: Dave Parks

FIXED

Use GL_SRGB8_ALPHA8 for the diffuse and specular buffers, and correct gamma *before* glow and other post processing effects that don't care about being gamma correct.

NORSPEC-57, NORSPEC-58  Remove sRGB and gamma correction from shaders to remove banding and not break all shiny objects.

SH-2908 Rework indexed texture rendering to use a uvec4 instead of a float for texture indices in the data stream.  Also rework gl_FragColor overrides to not collide with some odd driver implementations.

SH-2465 Move FXAA to its own pass independent of DoF (also removes the need to reload shaders when toggling FSAA on and off)

SH-2243 work in progress -- don't use gl_FragColor or gl_FragData for outputs -- no more deprecation warnings on nvidia

SH-2242 FXAA support instead of unreliable multisample textures (done here because it's a smaller change than integrating glVertexAttrib with FSAA pipe).  Shader integration with LLDynamicTexture subclasses.

SH-1682 Dynamically adjust the number of texture channels to use for indexed texture rendering based on available hardware.

SH-1455 Faster, better, more reliable disabling of DoF effect when edit menu is open and when effect is opted out of.

See https://wiki.lindenlab.com/wiki/License_Substitution for details.

Self reviewed.