The new renderers don't support them due to the required complexity of
integrating them with Vulkan and the assumptions those nodes make about
the renderer (the GL renderer exports its internal APIs into the
GLShader).
There haven't been any complaints that I'm aware of since 4.14 was
released where the default renderer does not support the nodes, so usage
in public seems to be close to nonexistant.
The 2 uses I know of were workarounds about missing features in GTK that
have stopped since GTK now supports them:
1. GStreamer used in to do premultiplication when the old GL renderer
did not do so in hardware but on the CPU.
2. Adwaita used it for masking before the mask node wa added in 4.10.
This adds a bunch of snazz to the gltransitions demo. It is perhaps
a bit overloaded now, but it demos everything that we can do.
Changes:
* The fire shader is now not a bin, it just renders an animating
background with no textures involved.
* The stacks don't all start on the same page.
* The shaderbin passes the mouse coordinate to the shader.
* The shaderbin allows specifying a "border" so that you can
cause effects outside the bin child (something that is new to gtk4).
* All the buttons and the stacks are now in shader-bins that runs
a wobbly-widget effect based on the mouse position that
wobbles outside the child allocation.
Add adds a demo showing off GskGLShaderNode in various ways.
It has a transistion widget, using some examples from
gl-transitions.com, with child widgets being both images, a GL area
and real widgets (that let you edit the transition shaders
themselves.
It also has a fancy fire effect on hove on the buttons.
