This backports the high quality glow mode from the `master` branch.
Previously, during downsample, every second row was ignored.
Now, when high-quality is used, we sample two rows at once to ensure
that no pixel is missed. It is slower, but looks much better and has
a much high stability while moving.
High quality also takes an additional horizontal sample the width of the
horizontal blur matches the height of the vertical blur.
As of clang-format 6.0.1, putting the `/* clang-format off */` hint
around our "invalid" `[vertex]` and `[shader]` statements isn't enough
to prevent a bogus indent of the next comments and first valid statement,
so we need to enclose that first valid statement in the unformatted chunk.
This commit adds a new rendering backend, GLES2, and adds a
project setting to enable it.
Currently this backend can only be used on the X11 platform,
but integrating into other platforms is planned.
Hugo Locurcio
Bastiaan Olij
Rémi Verschelde
clayjohn
karroffel