linear will average all the pixels for the lod, nearest will just pick
one (using the same method as OpenGL/Vulkan, picking bottom right
center).
This doesn't really make linear/nearest filtering work as it should
(because it's still a form of mipmaps), but it has 2 advantages:
1. it gets closer to the desired effect
2. it is a lot faster
Because only 1 pixel is chosen from the original image, instead of
averaging all pixels, a lot less memory needs to be accessed, and
because memory access is the bottleneck for large images, the speedup is
almost linear with the number of pixels not accessed.
And that means that even for lot level 3, aka 1/8th scale, only 1/64 of
the pixels need to be accessed, and everything is 50x faster.
Switching gtk4-demo --run=image_scaling to linear/nearest makes all the
lag go away for me, even with a 64k x 64k image.
We have fast conversion functions, use those directly instead of calling
into gdk_memory_convert().
This is useful because as mentioned before, the main optimization here
is RGB8 => RGBA8 and we have a fastpath for that.
Why do we need this? Because RGB images are provided in RGB format but
GPUs can't handle RGB, only RGBA, so we need to convert.
And we need to do that without allocating too much memory, because
allocating memory is slow. Which means in aprticular we need to do the
conversion after mipmapping, not before (like we were doing).
This allows uploading less memory but requires computing lod levels on
the CPU which is slow because it reads through all of the memory and so
far entirely not optimized.
However, it uses significantly less VRAM.
This is done by adding a gdk_memory_mipmap() function that does this
task.
The texture upload op now accepts a lod level and if that is >0 it uses
gdk_memory_mipmap() on the source texture.
This matches what the gpu renderer does when printing
colorstates.
It also avoids it printing "S*RGBA8" for the format and instead prints
"SRGBA8(p)" now.
convert_func2 is a 'from' conversion function, ie it expects to
be passed the target color state. This was wrong both in
gdk_memory_convert and gdk_memory_convert_color_state.
... and plumb the color state through the downloading machinery, where
no matter what path it takes it ends up in
gdk_memory_convert_color_state() or gdk_memory_convert().
The 2nd of those has been expanded to optionally do colorstate
conversion when the 2 colorstates are different.
That's basically the "undefined" value. We need that when drawing
nothing, which so far only happens with empty container nodes.
But empty container nodes can be children of other nodes, and that makes
things propagate. So instead of catching them, force the whole rest of
the code to deal with an undefined depth.
We also can't just set a random depth, because that will cause merging
to fail.
This is an experiment for now, but it seems that encoding srgb inside
the depth makes sense, as we not just use depth to decide on the
GL fbconfigs/Vulkan formats to pick, depth also encodes how the [0...1]
color values are quantized when stored.
Let's see where this goes.
This is useful in debugging.
The names I chose are shortened a bit from the enum values. We
use just a single depth, * for premultiplied, and f for float.
In GLES, BGRA is still done by GL_EXT_texture_format_BGRA8888 which is
an extension that is older than GLES 2.0.
And back then, internal formats had to be specified unsized. And when
that was changed with GLES3, nobody updated the extension.
However, on OpenGL, this extension doesn't exist, and internal formats
need to be sized.
So let's use different internal formats depending on GL version.
Fixes#6333
Track fallback formats to use in the memoryformat directly instead of
using in the GL uploading code.
First of all, this allows sharing the code and ensuring all our
renderers use the same fallback mechanism.
But also, this allows tracking fallbacks per-format which is useful
because the fallback formats aren't really a tree. We want to make
FLOAT16 fall back to FLOAT32 when not available, but we also want
FLOAT32 fall back to FLOAT16.
By tracking the fallbacks per-format, we can achieve that.
Add gdk_memory_format_get_premultiplied() and
gdk_memory_format_get_straight() which return the matching
premultiplied/straight format.
Use this to pick the premultiplied format when uploading GL textures.
And remove the duplication in the dmabuf code, where we can now use
these functions instead of tracking both the premultiplied and straight
alpha versions.
Add an "RGBA" format that just maps to the swizzled version of the
default format.
This way, BGR gets mapped to RGB + swizzling first before trying to map
it to the default format for the depth.
The benefit here is that this format has the same memory width, so
uploading/downloading code can treat it equivalent to the original
format and there's no conversion neccessary later.
Now that we have gdk_gl_context_get_memory_flags() and code can use that
function, make the code do that.
Remove support checks from gdk_memory_format_gl_format().
This is an initial naive port that doesn't try to make use of the finer-grained
flags yet.
