Implemented split barriers (closed https://github.com/DiligentGraphics/DiligentCore/issues/43).

2 files changed, 51 insertions, 15 deletions

diff --git a/Graphics/GraphicsEngine/include/DeviceContextBase.h b/Graphics/GraphicsEngine/include/DeviceContextBase.h
index 959eafae..51420d83 100644
--- a/Graphics/GraphicsEngine/include/DeviceContextBase.h
+++ b/Graphics/GraphicsEngine/include/DeviceContextBase.h
@@ -934,12 +934,13 @@ void DeviceContextBase<BaseInterface,ImplementationTraits> ::
 {
     DEV_CHECK_ERR((Barrier.pTexture != nullptr) ^ (Barrier.pBuffer != nullptr), "Exactly one of pTexture or pBuffer members of StateTransitionDesc must not be null");
     DEV_CHECK_ERR(Barrier.NewState != RESOURCE_STATE_UNKNOWN, "New resource state can't be unknown");
+    RESOURCE_STATE OldState = RESOURCE_STATE_UNKNOWN;
     if (Barrier.pTexture)
     {
         const auto& TexDesc = Barrier.pTexture->GetDesc();
         
         DEV_CHECK_ERR(VerifyResourceStates(Barrier.NewState, true), "Invlaid new state specified for texture '", TexDesc.Name, "'");
-        auto OldState = Barrier.OldState != RESOURCE_STATE_UNKNOWN ? Barrier.OldState : Barrier.pTexture->GetState();
+        OldState = Barrier.OldState != RESOURCE_STATE_UNKNOWN ? Barrier.OldState : Barrier.pTexture->GetState();
         DEV_CHECK_ERR(OldState != RESOURCE_STATE_UNKNOWN, "The state of texture '", TexDesc.Name, "' is unknown to the engine and is not explicitly specified in the barrier");
         DEV_CHECK_ERR(VerifyResourceStates(OldState, true), "Invlaid old state specified for texture '", TexDesc.Name, "'");
 
@@ -968,10 +969,20 @@ void DeviceContextBase<BaseInterface,ImplementationTraits> ::
     {
         const auto& BuffDesc = Barrier.pBuffer->GetDesc();
         DEV_CHECK_ERR(VerifyResourceStates(Barrier.NewState, false), "Invlaid new state specified for buffer '", BuffDesc.Name, "'");
-        auto OldState = Barrier.OldState != RESOURCE_STATE_UNKNOWN ? Barrier.OldState : Barrier.pBuffer->GetState();
+        OldState = Barrier.OldState != RESOURCE_STATE_UNKNOWN ? Barrier.OldState : Barrier.pBuffer->GetState();
         DEV_CHECK_ERR(OldState != RESOURCE_STATE_UNKNOWN, "The state of buffer '", BuffDesc.Name, "' is unknown to the engine and is not explicitly specified in the barrier");
         DEV_CHECK_ERR(VerifyResourceStates(OldState, false), "Invlaid old state specified for buffer '", BuffDesc.Name, "'");
     }
+
+    if (OldState == RESOURCE_STATE_UNORDERED_ACCESS && Barrier.NewState == RESOURCE_STATE_UNORDERED_ACCESS)
+    {
+        DEV_CHECK_ERR(Barrier.TransitionType == STATE_TRANSITION_TYPE_IMMEDIATE, "For UAV barriers, transition type must be STATE_TRANSITION_TYPE_IMMEDIATE");
+    }
+
+    if (Barrier.TransitionType == STATE_TRANSITION_TYPE_BEGIN)
+    {
+        DEV_CHECK_ERR(!Barrier.UpdateResourceState, "Resource state can't be updated in begin-split barrier");
+    }
 }
 
 template<typename BaseInterface, typename ImplementationTraits>
diff --git a/Graphics/GraphicsEngine/interface/GraphicsTypes.h b/Graphics/GraphicsEngine/interface/GraphicsTypes.h
index d515b2a1..1e605009 100644
--- a/Graphics/GraphicsEngine/interface/GraphicsTypes.h
+++ b/Graphics/GraphicsEngine/interface/GraphicsTypes.h
@@ -1659,6 +1659,24 @@ namespace Diligent
                                               RESOURCE_STATE_COPY_SOURCE
     };
 
+    /// State transition barrier type
+    enum STATE_TRANSITION_TYPE : Uint8
+    {
+        /// Perform state transition immediately.
+        STATE_TRANSITION_TYPE_IMMEDIATE = 0,
+
+        /// Begin split barrier. This mode only has effect in Direct3D12 backend, and corresponds to
+        /// [D3D12_RESOURCE_BARRIER_FLAG_BEGIN_ONLY](https://docs.microsoft.com/en-us/windows/desktop/api/d3d12/ne-d3d12-d3d12_resource_barrier_flags)
+        /// flag. See https://docs.microsoft.com/en-us/windows/desktop/direct3d12/using-resource-barriers-to-synchronize-resource-states-in-direct3d-12#split-barriers.
+        /// In other backends, begin-split barriers are ignored.
+        STATE_TRANSITION_TYPE_BEGIN,
+
+        /// End split barrier. This mode only has effect in Direct3D12 backend, and corresponds to
+        /// [D3D12_RESOURCE_BARRIER_FLAG_END_ONLY](https://docs.microsoft.com/en-us/windows/desktop/api/d3d12/ne-d3d12-d3d12_resource_barrier_flags)
+        /// flag. See https://docs.microsoft.com/en-us/windows/desktop/direct3d12/using-resource-barriers-to-synchronize-resource-states-in-direct3d-12#split-barriers.
+        /// In other backends, this mode is similar to STATE_TRANSITION_TYPE_IMMEDIATE.
+        STATE_TRANSITION_TYPE_END
+    };
 
     /// Resource state transition barrier description
     struct StateTransitionDesc
@@ -1693,25 +1711,31 @@ namespace Diligent
         /// Resource state after transition.
         RESOURCE_STATE NewState = RESOURCE_STATE_UNKNOWN;
 
+        /// State transition type, see Diligent::STATE_TRANSITION_TYPE.
+
+        /// \note When issuing UAV barrier (i.e. OldState and NewState equal RESOURCE_STATE_UNORDERED_ACCESS),
+        ///       TransitionType must be STATE_TRANSITION_TYPE_IMMEDIATE.
+        STATE_TRANSITION_TYPE TransitionType = STATE_TRANSITION_TYPE_IMMEDIATE;
+
         /// If set to true, the internal resource state will be set to NewState and the engine
-        /// will be able to take the resource state management. In this case it is the 
+        /// will be able to take over the resource state management. In this case it is the 
         /// responsibility of the application to make sure that all subresources are indeed in
         /// designated state.
-        /// If set to false, internal resource state will be set to RESOURCE_STATE_UNKNOWN, and the 
-        /// engine will not manage or check the resource state in all further operations until the
-        /// state is set to a known value.
+        /// If set to false, internal resource state will be unchanged.
+        /// \note When TransitionType is STATE_TRANSITION_TYPE_BEGIN, this member must be false.
         bool UpdateResourceState = false;
 
         StateTransitionDesc(){}
 
-        StateTransitionDesc(ITexture*      _pTexture, 
-                            RESOURCE_STATE _OldState,
-                            RESOURCE_STATE _NewState, 
-                            Uint32         _FirstMipLevel   = 0,
-                            Uint32         _MipLevelsCount  = RemainingMipLevels,
-                            Uint32         _FirstArraySlice = 0,
-                            Uint32         _ArraySliceCount = RemainingArraySlices,
-                            bool           _UpdateState     = false) : 
+        StateTransitionDesc(ITexture*             _pTexture, 
+                            RESOURCE_STATE        _OldState,
+                            RESOURCE_STATE        _NewState, 
+                            Uint32                _FirstMipLevel   = 0,
+                            Uint32                _MipLevelsCount  = RemainingMipLevels,
+                            Uint32                _FirstArraySlice = 0,
+                            Uint32                _ArraySliceCount = RemainingArraySlices,
+                            STATE_TRANSITION_TYPE _TransitionType  = STATE_TRANSITION_TYPE_IMMEDIATE,
+                            bool                  _UpdateState     = false) : 
             pTexture            (_pTexture),
             FirstMipLevel       (_FirstMipLevel),
             MipLevelsCount      (_MipLevelsCount),
@@ -1719,6 +1743,7 @@ namespace Diligent
             ArraySliceCount     (_ArraySliceCount),
             OldState            (_OldState),
             NewState            (_NewState),
+            TransitionType      (_TransitionType),
             UpdateResourceState (_UpdateState)
         {}
 
@@ -1726,7 +1751,7 @@ namespace Diligent
                             RESOURCE_STATE _OldState,
                             RESOURCE_STATE _NewState, 
                             bool           _UpdateState) :
-            StateTransitionDesc(_pTexture, _OldState, _NewState, 0, RemainingMipLevels, 0, RemainingArraySlices, _UpdateState)
+            StateTransitionDesc(_pTexture, _OldState, _NewState, 0, RemainingMipLevels, 0, RemainingArraySlices, STATE_TRANSITION_TYPE_IMMEDIATE, _UpdateState)
         {}
 
         StateTransitionDesc(IBuffer*       _pBuffer,