bgfx crashing app when used as an overlay

[leryss]

I'm trying to make an overlay app for games. Basically I'm finding the directx device & render target of the game and the window of the game and passing these to the PlatformData init object. bgfx succesfully renders one frame before crashing the app. The rendered stuff is visible right before the crash.

What are your thoughts on this ? I'm not familiar with the library so I cant tell what is wrong here

graphics_engine::graphics_engine(void* context, void* render_target, void* window)
{
	bgfx::Init init;
	init.platformData.context = context;
	init.platformData.backBuffer = render_target;
	init.platformData.nwh = window;

	if (!bgfx::init(init))
		throw_runtime_error("Failed to init render engine. BGFX failed to init");

	bgfx::setDebug(BGFX_DEBUG_TEXT);
	bgfx::setViewRect(0, 0, 0, uint16_t(1920), uint16_t(1080));
	bgfx::setViewClear(0, BGFX_CLEAR_NONE);
}

void graphics_engine::render()
{
	bgfx::touch(0);

	bgfx::dbgTextClear();
	bgfx::dbgTextPrintf(0, 1, 0x0f, "Color can be changed with ANSI \x1b[9;me\x1b[10;ms\x1b[11;mc\x1b[12;ma\x1b[13;mp\x1b[14;me\x1b[0m code too.");

	bgfx::frame();
}

Ive also tried to backup and restore dx11 state before & after render() (exactly how imgui does it, since I saw that imgui doesnt crash the game)

[bkaradzic]

bgfx succesfully renders one frame before crashing the app. The rendered stuff is visible right before the crash.

What's the actual crash?!

[leryss]

Unhandled exception at 0x00007FF8005E4F69 in game.exe: Microsoft C++ exception: ExceptionD3D11 at memory location 0x000000E5857FF068.

It seems that it crashes in the game code.
I also tried forcing bgfx to run in one thread as per documentation I called bgfx::renderFrame() before init, if I do that the crash dissapears but nothing is rendering. Also if I supply NULL instead of the directx device & render target, it works but even though the clearColor is NONE it doesnt blend with the game screen

[leryss]

also is there a way to prevent bgfx from calling directx Present function when I call bgfx::frame ?

[bkaradzic]

It seems that it crashes in the game code.

So it's not bgfx...

also is there a way to prevent bgfx from calling directx Present function when I call bgfx::frame ?

If you don't render anything, frame won't call present... bgfx is really not designed for this particular use case, you should find something else instead.

[leryss]

Finally I was able to make it work. A few things I did for people who might try to do the same thing as me:

1. Compile bgfx with multithreading off, turns out this was causing the game to crash
2. If you are hooking a directx11 game make sure you set the render target you gave bgfx before drawing using OMSetRenderTargets, in my case the game was changing the render target from the directx device.