On Friday, 24 May 2024 at 19:22:32 UTC, Jonathan Gerlach wrote:
I'm impressed. Are you using DirectX "11 on 12" or standard
DirectX11? Did you need to avoid the GC at all? I imagine the
GC could ruin your framerate if you're not careful. Thanks for
sharing and congrats on finishing (close enough) your game.
Plain old DX11. I've used DX12 in industry, and it basically
amounts to opting in to writing 70% of the graphics driver along
with your renderer :) I don't need to push AAA levels of
performance or asset load for this game, so DX11 is fine.
Regarding the GC, copy-pasting my reply from Discord:
I don't have the GC fully disabled, but I make a point to avoid
GC allocations in runtime code. I allow myself to use it for
initialization, tooling, editor code, etc. For runtime code it
really just acts as a fallback. If I messed something up, a
memory leak just becomes a periodic hitch instead of an eventual
crash.
I've also hacked some changes into druntime to help with this:
- I added a "scrapheap" GC implementation, which is a simple
linear allocator that resets at the end of each frame. I have a
mixin that makes a scope use the scrapheap instead of the regular
GC, which is useful for allowing me to still use phobos or other
libraries, as long as I'm okay with all allocated memory being
discarded at the end of the frame. Each worker thread also gets
one, which resets when a unit of work completes.
- I added a quick and dirty mode I can enable that logs the
callstack of every GC allocation, to help me track down stray
allocations that occur during runtime. @nogc is too restrictive,
and doesn't understand that my scrapheap usage bypasses the GC.
Runtime allocations that need to stick around almost entirely use
a structure I've internally called a GenerationalStorage. Pretty
common idea in games, a fixed size object pool that hands out
IDs, and IDs can be used to retrieve a pointer to the object.
Each ID contains the object's index, along with a generation
number that increments every allocation, letting you reliably
catch and assert on any use-after-frees of IDs.
