From d118d3582076b0a8e1ebca2ad520f23ab541269b Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Fri, 26 Feb 2021 02:38:26 +0100
Subject: [PATCH] [d3d11] Fix IAGetIndexBuffer with optimized index buffers

---
 src/d3d11/d3d11_context.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/d3d11/d3d11_context.cpp b/src/d3d11/d3d11_context.cpp
index f9c685400..b051b5e28 100644
--- a/src/d3d11/d3d11_context.cpp
+++ b/src/d3d11/d3d11_context.cpp
@@ -1740,8 +1740,12 @@ namespace dxvk {
     if (pFormat != nullptr)
       *pFormat = m_state.ia.indexBuffer.format;
     
-    if (pOffset != nullptr)
-      *pOffset = m_state.ia.indexBuffer.offset;
+    if (pOffset != nullptr) {
+      uint32_t shift = m_state.ia.indexBuffer.format == DXGI_FORMAT_R16_UINT ? 1 : 2;
+      *pOffset = m_state.ia.indexBuffer.optimized
+        ? m_state.ia.indexBuffer.firstIndex << shift
+        : m_state.ia.indexBuffer.offset;
+    }
   }