Initial transform feedback support (#1370)

* Initial transform feedback support

* Some nits and fixes

* Update ReportCounterType and Write method

* Can't change shader or TFB bindings while TFB is active

* Fix geometry shader input names with new naming

Ryujinx.Graphics.OpenGL/EnumConversion.cs

@@ -331,6 +331,31 @@ namespace Ryujinx.Graphics.OpenGL
             return PrimitiveType.Points;
         }
 
+        public static TransformFeedbackPrimitiveType ConvertToTfType(this PrimitiveTopology topology)
+        {
+            switch (topology)
+            {
+                case PrimitiveTopology.Points:
+                    return TransformFeedbackPrimitiveType.Points;
+                case PrimitiveTopology.Lines:
+                case PrimitiveTopology.LineLoop:
+                case PrimitiveTopology.LineStrip:
+                case PrimitiveTopology.LinesAdjacency:
+                case PrimitiveTopology.LineStripAdjacency:
+                    return TransformFeedbackPrimitiveType.Lines;
+                case PrimitiveTopology.Triangles:
+                case PrimitiveTopology.TriangleStrip:
+                case PrimitiveTopology.TriangleFan:
+                case PrimitiveTopology.TrianglesAdjacency:
+                case PrimitiveTopology.TriangleStripAdjacency:
+                    return TransformFeedbackPrimitiveType.Triangles;
+            }
+
+            Logger.PrintDebug(LogClass.Gpu, $"Invalid {nameof(PrimitiveTopology)} enum value: {topology}.");
+
+            return TransformFeedbackPrimitiveType.Points;
+        }
+
         public static OpenTK.Graphics.OpenGL.StencilOp Convert(this GAL.StencilOp op)
         {
             switch (op)

Ryujinx.Graphics.OpenGL/Pipeline.cs

@@ -45,6 +45,8 @@ namespace Ryujinx.Graphics.OpenGL
 
         private bool _scissor0Enable = false;
 
+        private bool _tfEnabled;
+
         ColorF _blendConstant = new ColorF(0, 0, 0, 0);
 
         internal Pipeline()
@@ -76,6 +78,12 @@ namespace Ryujinx.Graphics.OpenGL
             GL.MemoryBarrier(MemoryBarrierFlags.AllBarrierBits);
         }
 
+        public void BeginTransformFeedback(PrimitiveTopology topology)
+        {
+            GL.BeginTransformFeedback(topology.ConvertToTfType());
+            _tfEnabled = true;
+        }
+
         public void ClearRenderTargetColor(int index, uint componentMask, ColorF color)
         {
             GL.ColorMask(
@@ -512,6 +520,12 @@ namespace Ryujinx.Graphics.OpenGL
             }
         }
 
+        public void EndTransformFeedback()
+        {
+            GL.EndTransformFeedback();
+            _tfEnabled = false;
+        }
+
         public void SetBlendState(int index, BlendDescriptor blend)
         {
             if (!blend.Enable)
@@ -713,7 +727,17 @@ namespace Ryujinx.Graphics.OpenGL
         public void SetProgram(IProgram program)
         {
             _program = (Program)program;
-            _program.Bind();
+
+            if (_tfEnabled)
+            {
+                GL.PauseTransformFeedback();
+                _program.Bind();
+                GL.ResumeTransformFeedback();
+            }
+            else
+            {
+                _program.Bind();
+            }
 
             SetRenderTargetScale(_fpRenderScale[0]);
         }
@@ -904,6 +928,22 @@ namespace Ryujinx.Graphics.OpenGL
             }
         }
 
+        public void SetTransformFeedbackBuffer(int index, BufferRange buffer)
+        {
+            const BufferRangeTarget target = BufferRangeTarget.TransformFeedbackBuffer;
+
+            if (_tfEnabled)
+            {
+                GL.PauseTransformFeedback();
+                GL.BindBufferRange(target, index, buffer.Handle.ToInt32(), (IntPtr)buffer.Offset, buffer.Size);
+                GL.ResumeTransformFeedback();
+            }
+            else
+            {
+                GL.BindBufferRange(target, index, buffer.Handle.ToInt32(), (IntPtr)buffer.Offset, buffer.Size);
+            }
+        }
+
         public void SetUniformBuffer(int index, ShaderStage stage, BufferRange buffer)
         {
             SetBuffer(index, stage, buffer, isStorage: false);
@@ -1132,7 +1172,7 @@ namespace Ryujinx.Graphics.OpenGL
                 {
                     // If the event has been flushed, then just use the values on the CPU.
                     // The query object may already be repurposed for another draw (eg. begin + end).
-                    return false; 
+                    return false;
                 }
 
                 if (compare == 0 && evt.Type == QueryTarget.SamplesPassed && evt.ClearCounter)
@@ -1145,7 +1185,7 @@ namespace Ryujinx.Graphics.OpenGL
             // The GPU will flush the queries to CPU and evaluate the condition there instead.
 
             GL.Flush(); // The thread will be stalled manually flushing the counter, so flush GL commands now.
-            return false; 
+            return false;
         }
 
         public bool TryHostConditionalRendering(ICounterEvent value, ICounterEvent compare, bool isEqual)

Ryujinx.Graphics.OpenGL/Program.cs

@@ -2,6 +2,10 @@ using OpenTK.Graphics.OpenGL;
 using Ryujinx.Common.Logging;
 using Ryujinx.Graphics.GAL;
 using Ryujinx.Graphics.Shader;
+using Ryujinx.Graphics.Shader.CodeGen.Glsl;
+using System;
+using System.Collections.Generic;
+using System.Linq;
 
 namespace Ryujinx.Graphics.OpenGL
 {
@@ -31,7 +35,7 @@ namespace Ryujinx.Graphics.OpenGL
         private int[] _textureUnits;
         private int[] _imageUnits;
 
-        public Program(IShader[] shaders)
+        public Program(IShader[] shaders, TransformFeedbackDescriptor[] transformFeedbackDescriptors)
         {
             _ubBindingPoints = new int[UbsPerStage  * ShaderStages];
             _sbBindingPoints = new int[SbsPerStage  * ShaderStages];
@@ -67,6 +71,54 @@ namespace Ryujinx.Graphics.OpenGL
                 GL.AttachShader(Handle, shaderHandle);
             }
 
+            if (transformFeedbackDescriptors != null)
+            {
+                List<string> varyings = new List<string>();
+
+                int cbi = 0;
+
+                foreach (var tfd in transformFeedbackDescriptors.OrderBy(x => x.BufferIndex))
+                {
+                    if (tfd.VaryingLocations.Length == 0)
+                    {
+                        continue;
+                    }
+
+                    while (cbi < tfd.BufferIndex)
+                    {
+                        varyings.Add("gl_NextBuffer");
+
+                        cbi++;
+                    }
+
+                    int stride = Math.Min(128 * 4, (tfd.Stride + 3) & ~3);
+
+                    int j = 0;
+
+                    for (; j < tfd.VaryingLocations.Length && j * 4 < stride; j++)
+                    {
+                        byte location = tfd.VaryingLocations[j];
+
+                        varyings.Add(Varying.GetName(location) ?? "gl_SkipComponents1");
+
+                        j += Varying.GetSize(location) - 1;
+                    }
+
+                    int feedbackBytes = j * 4;
+
+                    while (feedbackBytes < stride)
+                    {
+                        int bytes = Math.Min(16, stride - feedbackBytes);
+
+                        varyings.Add($"gl_SkipComponents{(bytes / 4)}");
+
+                        feedbackBytes += bytes;
+                    }
+                }
+
+                GL.TransformFeedbackVaryings(Handle, varyings.Count, varyings.ToArray(), TransformFeedbackMode.InterleavedAttribs);
+            }
+
             GL.LinkProgram(Handle);
 
             for (int index = 0; index < shaders.Length; index++)

Ryujinx.Graphics.OpenGL/Renderer.cs

@@ -44,9 +44,9 @@ namespace Ryujinx.Graphics.OpenGL
             return Buffer.Create(size);
         }
 
-        public IProgram CreateProgram(IShader[] shaders)
+        public IProgram CreateProgram(IShader[] shaders, TransformFeedbackDescriptor[] transformFeedbackDescriptors)
         {
-            return new Program(shaders);
+            return new Program(shaders, transformFeedbackDescriptors);
         }
 
         public ISampler CreateSampler(SamplerCreateInfo info)