According to Erik @ NVidia the open source NVidia driver will not
create a EGLImage from a DMABUF if the target is not
GL_TEXTURE_EXTERNAL_OES. This change set converts the dmabuf texture
from GL_TEXTURE_2D to GL_TEXTURE_EXTERNAL_OES and at runtime performs a
global search & replace on fragment shaders as needed to remain
compatible, replacing `sampler2D` with `samplerExternalOES`.
Ref: https://github.com/NVIDIA/open-gpu-kernel-modules/discussions/243#discussioncomment-3283415
This fixes a rounding issue on certain hardware (NVidia) which actually
implement mediump as half precision (16-bit) float. It's safe to assume
`highp` is available as if the GPU does not support it, then the shader
compiler will try to find a lower precision that is supported by the GPU
This saves a lot of GPU power for partial updates. Running testufo with
lanczos downscaling and FSR upscaling consumed over 90 W, but with this
commit, consumed only 75 W.
Using 4x4 means that some pixels will be outside of the lanczos window. The
ideal lanczos function should in fact be zero in those areas, so we shouldn't
waste time processing those pixels.
I can't notice any difference in the results.
gl_Position is expected to be using homogeneous coordinates, which requires
w to be a coordinate scale factor, usually 1.0. z should also be set in order
for depth to be well-defined. Therefore, we should set gl_Position.zw to
vec2(0.0, 1.0).
The $escape+S keybinding now cycles through the available scale algorithms.
This allows the user to switch between algorithms if the automatic detection
turns out to be problematic.
The algorithms are renumbered so that 0 can be LG_SCALE_AUTO.
This commit fixes the issues with the meaning of useNearest being flipped
by removing the variable and use enumerations.
We define an enumeration EGL_DesktopScaleType to express the type of scaling
needed to be performed: no scaling, upscaling, or downscaling. This is
updated when either the frame size or the viewport size changes.
Previously, we only updated the useNearest when the frame size changes.
The desktop shader can now support an enumeration of scaling algorithms,
although only nearest and linear are currently implemented.
Like before, nearest is used when not scaling or upscaling, and linear is
used when downscaling.
This should prevent the looking-glass-client window from having an alpha
channel. On Wayland, the alpha channel is used to compose the window onto
the desktop, so the wallpaper would bleed through unless set to complete
opaque.
We worked around this by using constant alpha for rendering, but it was
not sustainable. Instead, we should just ask for 24-bit context.
We ask for 32-bit colour buffer when creating the EGL context. On Wayland,
this sometimes give contexts with alpha channels, resulting in unwanted
transparency. So we clear the alpha channel in the desktop shader.
We also switch to using constant alpha for blending the splash, which
avoids more alpha issues.
