Previously, we translated the uniform key (an enum) into a location within
the shader program in GskNglProgram. A number of performance improvements
were focused around having low nubers for the uniform locations. Generally
this is the case, but some drivers such as old Intel drivers on Windows
may use rather large numbers for those.
To combat this, we can push the translation of uniform keys into locations
at the GskNglUniformState level so that we work with unranslated keys
through the process until applying them.
Fixes#3780
The effectiveness of the front cache is limited by
subpixel positioning making it very likely that we
will meet the same glyph in different x phases inside
a single line of text.
Factoring the xphase into the front cache key makes things
better. For the string eeeeeeeeeeeeeeeeeee
before: 0% front cache hits
after: >90% front cache hits
We don't want to be responsible for duplicating the effort of the hash
table, we just want to speed up subsequent lookups. Otherwise, we risk
not marking glyph usage when tracking usage for compaction.
This required finishing up the begin_frame/end_frame semantics for
GskNglTextureLibraryw which was apparently overlooked.
The driver was changed to provide more information to the library when
beginning frames. We do not need to use end_frame so that was removed.
The frame age is the same as GL (60) but I do wonder if that is based
on seconds if we should be using something longer for situations where
we have higher frame rates.
Fixes#3771
Recognize a common pattern: A rounded clip with
a color node, followed by a border node, with the
same outline. This is what CSS backgrounds frequently
produce, and we can render it more efficiently with
a combined shader.
Now that colors aren't uniforms anymore, we don't
win much by using the inset_shadow shader. The fragment
shaders of inset_shadow and border are identical. And
the regular border setup does nine-slicing.
Colors are not state that we carry across draw ops,
so setting the color on the render job doesn't make
much sense. Instead, pass the color to the various
draw calls. Add a few new ones for that purpose.
Also, shorten the names of some by going from
'load_vertices_from_offscreen' to 'draw_offscreen'.
This reduces how many changes we make when recording uniform state, which
increases the chances that the data offset will be the same when applying
uniforms.
Since we make full snapshots when recording uniform state of batches, we
need to perform some deduplication to avoid so many repeated uniform calls.
This uses a closed hashtable to determine if we are likely changing the
value to something new.
This does not currently compare values, it instead only compares that we
are going to point at a new offset into the uniform buffer. We could go
further if we compare upon updating values (we did that early on in the
prototype) so that offsets are less likely to be changed.
When the color passed is transparent black, use
the color from the texture as source, instead of
as mask. This lets use use the coloring program
both for regular and color glyphs, avoiding
program changes in text with Emoji.
Instead of using uniforms for color used in multiple
programs, pass it as vertex attributes. This will let
us batch more draw calls, since we don't have to change
uniforms so often. In particular, for syntax-highlighted
text.
We may want to change the interface between the
shaders and the renderer for ngl, and therefore,
sharing the shaders between gl and ngl will not
be practical, going forward.
The primary goal here was to cleanup the current GL renderer to make
maintenance easier going forward. Furthermore, it tracks state to allow
us to implement more advanced renderer features going forward.
Reordering
This renderer will reorder batches by render target to reduce the number
of times render targets are changed.
In the future, we could also reorder by program within the render target
if we can determine that vertices do not overlap.
Uniform Snapshots
To allow for reordering of batches all uniforms need to be tracked for
the programs. This allows us to create the full uniform state when the
batch has been moved into a new position.
Some care was taken as it can be performance sensitive.
Attachment Snapshots
Similar to uniform snapshots, we need to know all of the texture
attachments so that we can rebind them when necessary.
Render Jobs
To help isolate the process of creating GL commands from the renderer
abstraction a render job abstraction was added. This could be extended
in the future if we decided to do tiling.
Command Queue
Render jobs create batches using the command queue. The command queue
will snapshot uniform and attachment state so that it can reorder
batches right before executing them.
Currently, the only reordering done is to ensure that we only visit
each render target once. We could extend this by tracking vertices,
attachments, and others.
This code currently uses an inline array helper to reduce overhead
from GArray which was showing up on profiles. It could be changed to
use GdkArray without too much work, but had roughly double the
instructions. Cycle counts have not yet been determined.
GLSL Programs
This was simplified to use XMACROS so that we can just extend one file
(gskglprograms.defs) instead of multiple places. The programs are added
as fields in the driver for easy access.
Driver
The driver manages textures, render targets, access to atlases,
programs, and more. There is one driver per display, by using the
shared GL context.
Some work could be done here to batch uploads so that we make fewer
calls to upload when sending icon theme data to the GPU. We'd need
to keep a copy of the atlas data for such purposes.
