The color-matrix shader was creating pixels with r,g,b > a in
some cases, which leads to unexpected test failures. In particular
this as visible the opacity render node test for opacity 0.
This is another example for a 2-texture shader.
So far, only separable blend modes are implemented.
The implementation is not optimized, with an
if-else cascade in the shader.
This commit takes several steps towards rendering text
like we want to.
The creation of the cairo surface and texture is moved
to the backend (in GskVulkanRenderer). We add a mask
shader that is used in the next text pipeline to use
the texture as a mask, like cairo_mask_surface does.
There is a separate color text pipeline that uses the
already existing blend shaders to use the texture as
a source, like cairo_paint does.
The text node api is simplified to have just a single
offset, which determines the left end of the text baseline,
like all our other text drawing APIs.
This fixes the proper dependencies getting set up for generating
the shaders and only the necessary things getting rebuilt on
resources changing in gsk.
Spooky action at a distance is not really allowed in Meson, so the rules
to generate the SPV files should go in their own directory.
Tested by: Rico Tzschichholz <ricotz@ubuntu.com>
Instead of having 3 different shaders for the different clipping
versions, just have one shader and use a preprocessor define to use
different clip functions.
That preprocessor define is set in the Makefile.
Also use foo.frag and foo.vert as the file extensions instead of using
foo.frag.glsl and foo.vert.glsl, as that's what glslc suggests as
extension.
That way we don't need to move the clip rounded rect manually through
the vertex shader into the fragment shader but can just look at the push
constants.
Simplifies shaders a lot.
Note: We interpolate premultiplied colors as per the CSS spec. This i
different from Cairo, which interpolates unpremultiplied.
So in testcases with translucent gradients, it's actually Cairo that is
wrong.
We can now upload vertices.
And we use this to draw a yellow background. Which is clearly superior
to not drawing anything.
Also, we have shaders now. If you modify them, you need glslc installed
so they can be recompiled into Spir-V bytecode.
