Implement transform feedback emulation for hardware without native support (#5080)

* Implement transform feedback emulation for hardware without native support

* Stop doing some useless buffer updates and account for non-zero base instance

* Reduce redundant updates even more

* Update descriptor init logic to account for ResourceLayout

* Fix transform feedback and storage buffers not being updated in some cases

* Shader cache version bump

* PR feedback

* SetInstancedDrawVertexCount must be always called after UpdateState

* Minor typo

2 files changed, 29 insertions, 1 deletions

diff --git a/src/Ryujinx.Graphics.Gpu/Engine/Threed/DrawManager.cs b/src/Ryujinx.Graphics.Gpu/Engine/Threed/DrawManager.cs
index 7438ba03..9c4921c8 100644
--- a/src/Ryujinx.Graphics.Gpu/Engine/Threed/DrawManager.cs
+++ b/src/Ryujinx.Graphics.Gpu/Engine/Threed/DrawManager.cs
@@ -539,6 +539,14 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
 
             engine.UpdateState();
 
+            if (instanceCount > 1)
+            {
+                // Must be called after UpdateState as it assumes the shader state
+                // has already been set, and that bindings have been updated already.
+
+                _channel.BufferManager.SetInstancedDrawVertexCount(count);
+            }
+
             if (indexed)
             {
                 _context.Renderer.Pipeline.DrawIndexed(count, instanceCount, firstIndex, firstVertex, firstInstance);
@@ -676,6 +684,8 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
                         _channel.BufferManager.SetIndexBuffer(br, IndexType.UInt);
                     }
 
+                    _channel.BufferManager.SetInstancedDrawVertexCount(_instancedIndexCount);
+
                     _context.Renderer.Pipeline.DrawIndexed(
                         _instancedIndexCount,
                         _instanceIndex + 1,
@@ -685,6 +695,8 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
                 }
                 else
                 {
+                    _channel.BufferManager.SetInstancedDrawVertexCount(_instancedDrawStateCount);
+
                     _context.Renderer.Pipeline.Draw(
                         _instancedDrawStateCount,
                         _instanceIndex + 1,
diff --git a/src/Ryujinx.Graphics.Gpu/Engine/Threed/StateUpdater.cs b/src/Ryujinx.Graphics.Gpu/Engine/Threed/StateUpdater.cs
index 5fa4702b..92e980ce 100644
--- a/src/Ryujinx.Graphics.Gpu/Engine/Threed/StateUpdater.cs
+++ b/src/Ryujinx.Graphics.Gpu/Engine/Threed/StateUpdater.cs
@@ -269,7 +269,7 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
                 _prevFirstVertex = _state.State.FirstVertex;
             }
 
-            bool tfEnable = _state.State.TfEnable;
+            bool tfEnable = _state.State.TfEnable && _context.Capabilities.SupportsTransformFeedback;
 
             if (!tfEnable && _prevTfEnable)
             {
@@ -1367,6 +1367,22 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
             _vsUsesDrawParameters = gs.Shaders[1]?.Info.UsesDrawParameters ?? false;
             _vsClipDistancesWritten = gs.Shaders[1]?.Info.ClipDistancesWritten ?? 0;
 
+            bool hasTransformFeedback = gs.SpecializationState.TransformFeedbackDescriptors != null;
+            if (hasTransformFeedback != _channel.BufferManager.HasTransformFeedbackOutputs)
+            {
+                if (!_context.Capabilities.SupportsTransformFeedback)
+                {
+                    // If host does not support transform feedback, and the shader changed,
+                    // we might need to update bindings as transform feedback emulation
+                    // uses storage buffer bindings that might have been used for something
+                    // else in a previous draw.
+
+                    _channel.BufferManager.ForceTransformFeedbackAndStorageBuffersDirty();
+                }
+
+                _channel.BufferManager.HasTransformFeedbackOutputs = hasTransformFeedback;
+            }
+
             if (oldVsClipDistancesWritten != _vsClipDistancesWritten)
             {
                 UpdateUserClipState();