Few questions about GL on GTK Master

[Chun-wei Fan (范君維) <fanc999 yahoo com tw>]

Hi,

Please pardon my ignorance about how things went in terms of the 
development for GTK+-4.

Few questions that I would like to ask:

-It seems to me that we don't do glBlitFramebuffer() directly in the 
code, as opposed to GTK+-3.x, as the FPS I had was about 20.0 versus 
60.0 (on GTK+-3.23.x) on my Windows 10 laptop (i7-6700HQ, nVidia 960m 
GTX graphics).  Can I know in GSK (or so) any pointers for the 
conditions that a "fast path" would be selected, as opposed to a 
"fallback/software (slow) path" , that I believe I am hitting?  It seems 
that I have the required extensions (as in GTK+-3) for using 
glBlitFramebuffer(), for both Desktop OpenGL and EGL via Googls's ANGLE, 
so is there something else that is being checked for in GTK+ master?

-At this point, it is possible to run with the GL GSK renderer while 
forcing EGL/GLES (i.e., setting GDK_DEBUG=gl-gles).  I saw shader 
compilation errors for both blur.fs.glsl and color_matrix.fs.glsl on 
both EGL/ANGLE, as well as running with the X11 backend on Ubuntu 18.04 
(the 'f' suffix for floats which are not allowed on GLSL 1.00; 
unresolved overloading of max() in blur.fs.glsl, invalid 
casts/conversions of int vs float).

Any pointers on these regards will be great.

With blessings, and cheers!