In many of the samples this is not a problem because they perform a full stall for demo purposes, but some of the more ‘real world’ samples do not.
They also do not teach how to deal with GPU systems where the present queue and the graphics rendering queue are different (I don’t know which systems have this setup, but I suspect it has to do with Optimus laptops and similar setups where GPU doing rendering is not the one hooked to the monitor).
This bug is hard to catch because often the race condition will never happen due to the nature of double and triple buffer, and worst case scenario this could result in tearing or similar artifacts (even if vsync is enabled).
Though there’s the possibility that failing to insert this barrier can result in severe artifacts in AMD GPUs due to DCC compression on render targets being dirty while rendering to it. Godot’s renderer had encountered this problem.
Once you get into the async mindset, Vulkan makes sense.
Where to next?
There’s a lot that needs to be done: Resizing the swapchain is not yet coded, separate Graphics and Present queues is not handled, there’s zero buffer management, no textures, no shaders.
The next task I’ll be focusing on is shaders; because they are useful to show stuff on screen and see if they’re working. Even if there are no vertex buffers yet, we can use gl_VertexID tricks to render triangles on screen.
And once shaders are working, we can then test if vertex buffers work once they’re ready, and if textures work, etc.
So lets put first things first; Ogre v1 and Ogre v2 are not only different versions of Ogre, but rather separate projects. Now officially.
While this sounds like big news, actually it is not that much of a change. If you followed the development of Ogre, you already noticed that the two branches moved independently in two separate directions. Hence, we had to write the what version to choose page.
Generally, Ogre2 focuses on the latest and fastest techniques, Ogre1 focuses on backward compatibility and keeping old projects running. Also Ogre1 is developed on github, while Ogre2 still lives on bitbucket.
With bitbucket now abandoning mercurial, we decided to move Ogre2 to github as well. While we could have kept it in a branch, we instead decided to create a separate repository with own issue tracking, landing page etc. So, enter ogre-next.
This also makes it possible to follow semver with Ogre1 and make a 2.0 release when needed.