This adds support for the extension and always
set the clip state value to 0..1 to align with vulkan
and metal. Moreover this is needed for the Reverse Z
implementation.
Note that this is a OpenGL 4.5 feature and is not
required to start Blender. So there must still be
a fallback path for now.
Rel #138898
Pull Request: https://projects.blender.org/blender/blender/pulls/138941
The use-case of this blend mode is to be able to make parts of an
viewport overlay transparent.
The future user of this blend mode is sequencer preview drawing
where frame will be drawn to an HDR render frame-buffer, and overlays
drawn on-top. In a way it is similar to the image engine, but without
need to have custom shader.
Ref #138094
Pull Request: https://projects.blender.org/blender/blender/pulls/138307
Metal and Vulkan don't support line smoothing. There is a workaround
implemented. This workaround is only enabled when linesmooth value is
larger than 1. However When using smooth lines it should also be used.
This is fixed by adding a `GPU_line_smooth_get` function for getting the
current line smooth state.
Pull Request: https://projects.blender.org/blender/blender/pulls/138123
