[PATCH resend 3/8] dxgi: Implement d3d12_swapchain_GetCurrentBackBufferIndex().

[Józef Kucia]

Signed-off-by: Józef Kucia 
---
 dlls/dxgi/swapchain.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/dlls/dxgi/swapchain.c b/dlls/dxgi/swapchain.c
index e20e973a7185..9c7024094d54 100644
--- a/dlls/dxgi/swapchain.c
+++ b/dlls/dxgi/swapchain.c
@@ -1291,9 +1291,11 @@ static HRESULT STDMETHODCALLTYPE d3d12_swapchain_GetMatrixTransform(IDXGISwapCha

static UINT STDMETHODCALLTYPE d3d12_swapchain_GetCurrentBackBufferIndex(IDXGISwapChain3 *iface)
 {
-    FIXME("iface %p stub!\n", iface);
+    struct d3d12_swapchain *swapchain = d3d12_swapchain_from_IDXGISwapChain3(iface);
+
+    TRACE("iface %p.\n", iface);

-    return 0;
+    return swapchain->current_buffer_index;
 }

static HRESULT STDMETHODCALLTYPE d3d12_swapchain_CheckColorSpaceSupport(IDXGISwapChain3 *iface,