libobs: Add function to count GPU adapters

Only implemented for D3D11 for now.

libobs-d3d11/d3d11-subsystem.cpp

@@ -2866,3 +2866,29 @@ extern "C" EXPORT void device_unregister_loss_callbacks(gs_device_t *device,
 		}
 	}
 }
+
+uint32_t gs_get_adapter_count(void)
+{
+	uint32_t count = 0;
+
+	const IID factoryIID = (GetWinVer() >= 0x602) ? dxgiFactory2
+						      : __uuidof(IDXGIFactory1);
+	ComPtr<IDXGIFactory1> factory;
+	HRESULT hr = CreateDXGIFactory1(factoryIID, (void **)factory.Assign());
+	if (SUCCEEDED(hr)) {
+		ComPtr<IDXGIAdapter1> adapter;
+		for (UINT i = 0;
+		     factory->EnumAdapters1(i, adapter.Assign()) == S_OK; ++i) {
+			DXGI_ADAPTER_DESC desc;
+			if (SUCCEEDED(adapter->GetDesc(&desc))) {
+				/* ignore Microsoft's 'basic' renderer' */
+				if (desc.VendorId != 0x1414 &&
+				    desc.DeviceId != 0x8c) {
+					++count;
+				}
+			}
+		}
+	}
+
+	return count;
+}

libobs/graphics/graphics-imports.c

@@ -210,6 +210,7 @@ bool load_graphics_imports(struct gs_exports *exports, void *module,
 	GRAPHICS_IMPORT_OPTIONAL(gs_duplicator_destroy);
 	GRAPHICS_IMPORT_OPTIONAL(gs_duplicator_update_frame);
 	GRAPHICS_IMPORT_OPTIONAL(gs_duplicator_get_texture);
+	GRAPHICS_IMPORT_OPTIONAL(gs_get_adapter_count);
 	GRAPHICS_IMPORT_OPTIONAL(device_texture_create_gdi);
 	GRAPHICS_IMPORT_OPTIONAL(gs_texture_get_dc);
 	GRAPHICS_IMPORT_OPTIONAL(gs_texture_release_dc);

libobs/graphics/graphics-internal.h

@@ -297,6 +297,8 @@ struct gs_exports {
 	bool (*gs_duplicator_update_frame)(gs_duplicator_t *duplicator);
 	gs_texture_t *(*gs_duplicator_get_texture)(gs_duplicator_t *duplicator);
 
+	uint32_t (*gs_get_adapter_count)(void);
+
 	gs_texture_t *(*device_texture_create_gdi)(gs_device_t *device,
 						   uint32_t width,
 						   uint32_t height);

libobs/graphics/graphics.c

@@ -2913,6 +2913,16 @@ bool gs_duplicator_update_frame(gs_duplicator_t *duplicator)
 	return thread_graphics->exports.gs_duplicator_update_frame(duplicator);
 }
 
+uint32_t gs_get_adapter_count(void)
+{
+	if (!gs_valid("gs_get_adapter_count"))
+		return 0;
+	if (!thread_graphics->exports.gs_get_adapter_count)
+		return 0;
+
+	return thread_graphics->exports.gs_get_adapter_count();
+}
+
 gs_texture_t *gs_duplicator_get_texture(gs_duplicator_t *duplicator)
 {
 	if (!gs_valid_p("gs_duplicator_get_texture", duplicator))

libobs/graphics/graphics.h

@@ -874,6 +874,8 @@ EXPORT void gs_duplicator_destroy(gs_duplicator_t *duplicator);
 EXPORT bool gs_duplicator_update_frame(gs_duplicator_t *duplicator);
 EXPORT gs_texture_t *gs_duplicator_get_texture(gs_duplicator_t *duplicator);
 
+EXPORT uint32_t gs_get_adapter_count(void);
+
 /** creates a windows GDI-lockable texture */
 EXPORT gs_texture_t *gs_texture_create_gdi(uint32_t width, uint32_t height);