partial_update is an EGL extension which allows us to inform the driver
ahead of time the limits of the areas we'll be writing to. This helps
performance for GPU hardware which renders into a local tile buffer:
informing the driver of the rendering extents means it can avoid
fetching unchanged tiles into the tile buffer and subsequently writing
them out.
The extension complements rather than replaces EGL_EXT_buffer_age (used
before partial_update to know which areas we need to update) and
EGL_KHR_swap_buffers_with_damage (used after partial_update to inform
the winsys of the changed region).
Note however that partial_update deals in buffer-damage regions ('what
has changed since the last time I used _this_ buffer?'), whereas
swap_buffers_with_damage deals in surface-damage regions ('what has
changed since the last time I rendered?'). An explanatory diagram can be
found in the specification:
https://www.khronos.org/registry/EGL/extensions/KHR/EGL_KHR_partial_update.txtFixes: #134
Signed-off-by: Daniel Stone <daniels@collabora.com>
Add some comments in the function to make it clear what's going on,
especially as we twist and turn between a lot of things called 'damage'
meaning different things in different co-ordinate spaces.
Signed-off-by: Daniel Stone <daniels@collabora.com>
The buffer_damage variable stores accumulated damage from previous
frames. This is the area that, before considering our current repaint
request, we need to repaint in order to bring the older buffer up to
date with the last buffer we rendered into.
Rename to previous_damage so it's a bit more clear what this refers to.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Technically it is storing which areas of the border are damaged.
However, we already have damage-region variables which need to be
translated by the border region. Rename the variable to not contain the
word 'damage' to reduce confusion.
Signed-off-by: Daniel Stone <daniels@collabora.com>
eglSwapBuffersWithDamage has to convert a damage region from Weston's
global co-ordinate space, into the co-ordinate space for EGL rendering
into a buffer for that output.
The conversion from the global co-ordinate space in logical pixels to
the output space in buffer pixels is slightly long and error-prone,
involving translating by the output's offset within the global
co-ordinate space, multiplying by output scale, and also translating to
allow for any borders we paint around the output.
After this is done, we need to flip the co-ordinates in the Y axis to
account for the lower-left-origin co-ordinate space used by EGL.
Since we want to reuse this for partial_update, but using a different
source region, extract this conversion into a well-commented helper we
can reuse.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Fan debug mode repaints the whole surface in order to clear any 'trails'
left over from previous fan paints. If this happens, fall back to using
regular eglSwapBuffers rather than eglSwapBuffersWithDamageEXT, since
the damage region we would pass will be too small.
Signed-off-by: Daniel Stone <daniels@collabora.com>
This fixes warnings for weston-debug, input, compositor, log and
linux-explicit-sync. Warnings range from swapping '[in]', '[out]' with
the function arguments to wrong parameter names.
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
GL-renderer is expected to grow more files, both by addition and by splitting.
Moving them into a new subdirectory helps people to understand which files are
relevant.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>
