CODEWITHSUNDEEP
c++windowsmultithreadingdirectx-11
yah_nosh
yah_nosh

Reputation: 165

Render to same target from multiple threads

I am working on an old C++ project on Windows, where I am upgrading the app's DirectX rendering engine (using DX11). The new engine that I made currently coexists with the old one, but it runs in a different thread and has its own DX device and context. Until now, I've been using two separate windows to display the results of the old and new rendering processes at the same time, which allows me to verify that the new engine correctly replicates the behavior of the old one.

Now I want to merge these windows and swap between them at runtime, i.e I would hook a button press, or some other control to pause one render thread and (re)start the other. Both would draw their results to the same window (i.e using the same HWND to create the render target and swap chain), but only one thread would be active at any one time. A good analogy would be some remastered games where they let you swap between the old and new graphics.

What is the most ideal way to achieve this? I was thinking of doing a "hot swap", i.e letting one thread start rendering without even waiting for the other thread to finish, since we know it will stop in the next frame, and I don't need them to be working together. Does this carry the risk of crashing, or any other problems? If all it would cause is a few incorrect frames during the swap, then I don't mind.

Upvotes: 0

Views: 454

Answers (1)

yah_nosh
yah_nosh

Reputation: 165

I tested it, no ill effects as far as I can tell, besides some flickering if both threads happen to try to draw at the same time.

Upvotes: 1

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