This change replaces a bare RenderEngine owned by a viewport
with a VeiwRender. This unlocks a possibility of accessing
RenderResult for viewport renders. Currently it is not done,
but it will be needed for an upcoming work towards unification
of the render passes handling.
Ref #108618
Currently no functional changes.
Preparing for introduction of a Render structure for the viewport
render which will hold both engine and the render result for
passes access.
Use proper allocation and destruction for it.
Since the allocation is no longer zero-initialized make sure the
fields are explicitly zeroed out. This also allows to use an easier
way to initialize mutexes.
Currently no functional changes, preparing for a bigger refactor.
Used for the global list of the Render structures.
Using C++ container helps moving towards reliable "real" C++
structure for the Render, without worrying about the offset of
the next/prev fields.
Should be no functional changes on the user side.
Sergey Sharybin