Vulkan swap chain: auto-detecting surface rotation on Android

2 files changed, 38 insertions, 9 deletions

diff --git a/Graphics/GraphicsEngine/interface/SwapChain.h b/Graphics/GraphicsEngine/interface/SwapChain.h
index 5a9bc956..d6ffa97e 100644
--- a/Graphics/GraphicsEngine/interface/SwapChain.h
+++ b/Graphics/GraphicsEngine/interface/SwapChain.h
@@ -64,19 +64,20 @@ DILIGENT_BEGIN_INTERFACE(ISwapChain, IObject)
 
     /// Changes the swap chain size
 
-    /// \param [in] NewWidth     - New swap chain width (not accounting for pre-transform), in pixels.
-    /// \param [in] NewHeight    - New swap chain height (not accounting for pre-transform), in pixels.
+    /// \param [in] NewWidth     - New logical swap chain width (not accounting for pre-transform), in pixels.
+    /// \param [in] NewHeight    - New logical swap chain height (not accounting for pre-transform), in pixels.
     /// \param [in] NewTransform - New surface transform, see Diligent::SURFACE_TRANSFORM.
     ///
     /// \note When resizing non-primary swap chains, the engine unbinds the
     ///       swap chain buffers from the output.
     ///
     ///       New width and height should not account for surface pre-transform. For example,
-    ///       if the window size is 1920 x 1080, but the surface is rotated by 90 degrees,
+    ///       if the window size is 1920 x 1080, but the surface is pre-rotated by 90 degrees,
     ///       NewWidth should still be 1920, and NewHeight should still be 1080. It is highly
-    ///       preferable to always use SURFACE_TRANSFORM_OPTIMAL, however SURFACE_TRANSFORM_ROTATE_90
-    ///       will also work in this scenario. After the swap chain has been resized, its width
-    ///       will be 1080, height will be 1920, and PreTransform will be SURFACE_TRANSFORM_ROTATE_90.
+    ///       recommended to always use SURFACE_TRANSFORM_OPTIMAL to let the engine select
+    ///       the most optimal pre-transform. However SURFACE_TRANSFORM_ROTATE_90 will also work in
+    ///       the scenario above. After the swap chain has been resized, its actual width will be 1080,
+    ///       actual height will be 1920, and PreTransform will be SURFACE_TRANSFORM_ROTATE_90.
     VIRTUAL void METHOD(Resize)(THIS_
                                 Uint32            NewWidth,
                                 Uint32            NewHeight,
diff --git a/Graphics/GraphicsEngineVulkan/src/SwapChainVkImpl.cpp b/Graphics/GraphicsEngineVulkan/src/SwapChainVkImpl.cpp
index e0e27333..732c47e5 100644
--- a/Graphics/GraphicsEngineVulkan/src/SwapChainVkImpl.cpp
+++ b/Graphics/GraphicsEngineVulkan/src/SwapChainVkImpl.cpp
@@ -845,10 +845,38 @@ void SwapChainVkImpl::Resize(Uint32 NewWidth, Uint32 NewHeight, SURFACE_TRANSFOR
                 VK_SURFACE_TRANSFORM_ROTATE_270_BIT_KHR |
                 VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_90_BIT_KHR |
                 VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_270_BIT_KHR;
-            if ((surfCapabilities.currentTransform & Rotate90TransformFlags) != 0)
+
+            if (NewWidth == 0 || NewHeight == 0)
+            {
+                NewWidth  = m_SurfaceIdentityExtent.width;
+                NewHeight = m_SurfaceIdentityExtent.height;
+
+                if ((surfCapabilities.currentTransform & Rotate90TransformFlags) != 0)
+                {
+                    // Swap to get logical dimensions as input NewWidth and NewHeight are
+                    // expected to be logical sizes.
+                    std::swap(NewWidth, NewHeight);
+                }
+            }
+
+            if (NewPreTransform == SURFACE_TRANSFORM_OPTIMAL)
             {
-                // The surface is rotated 90/270 degrees - swap width and height
-                std::swap(NewWidth, NewHeight);
+                if ((surfCapabilities.currentTransform & Rotate90TransformFlags) != 0)
+                {
+                    // Swap to get physical dimensions
+                    std::swap(NewWidth, NewHeight);
+                }
+            }
+            else
+            {
+                // Swap if necessary to get desired sizes after pre-transform
+                if (NewPreTransform == SURFACE_TRANSFORM_ROTATE_90 ||
+                    NewPreTransform == SURFACE_TRANSFORM_ROTATE_270 ||
+                    NewPreTransform == SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_90 ||
+                    NewPreTransform == SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_270)
+                {
+                    std::swap(NewWidth, NewHeight);
+                }
             }
         }
         else