Apparently this is something new that seems exciting for Linux graphics. I think that we are starting to see a new era where Linux graphics start moving into Windows/Mac OS level of quality graphics.
The GTK 4.13.5 release includes not one, but two new renderers. Their names are vulkan and ngl, and we also call them unified renderers, since they are built from the same sources. The new renderers can handle many corner cases correctly that the current gl renderer does not handle, and they offer advantages such as antialiasing and supersampled gradients.
The ngl renderer does not currently support GLES 2.
The new renderers are still considered experimental, and GTK will only use them if they are explicitly selected using the GSK_RENDERER environment variable. The default renderer is still the current gl renderer.
As part of this work, the GSK include files have been rearranged. It is no longer necessary to include renderer-specific headers for ngl and vulkan (and doing so will trigger deprecation warnings), and their constructors are always available.
The previously available experimental GdkVulkanContext APIs and the old Vulkan renderer have been removed.
Vulkan support is now enabled by default, and Linux distributions should build GTK with Vulkan. This requires the glslc shader compiler as a new dependency.
Vulkan is now also used for dmabuf support.