From 4c0eb91d7e6bdbe42ffa6e950e3288f8066de089 Mon Sep 17 00:00:00 2001
From: riperiperi <rhy3756547@hotmail.com>
Date: Tue, 20 Sep 2022 22:38:48 +0100
Subject: Convert Quads to Triangles in Vulkan (#3715)

* Add Index Buffer conversion for quads to Vulkan

Also adds a reusable repeating pattern index buffer to use for non-indexed
draws, and generalizes the conversion cache for buffers.

* Fix some issues

* End render pass before conversion

* Resume transform feedback after we ensure we're in a pass.

* Always generate UInt32 type indices for topology conversion

* No it's not.

* Remove unused code

* Rely on TopologyRemap to convert quads to tris.

* Remove double newline

* Ensure render pass ends before stride or I8 conversion
---
 Ryujinx.Graphics.Vulkan/HelperShader.cs | 81 +++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

(limited to 'Ryujinx.Graphics.Vulkan/HelperShader.cs')

diff --git a/Ryujinx.Graphics.Vulkan/HelperShader.cs b/Ryujinx.Graphics.Vulkan/HelperShader.cs
index 2eec92f0..0201de0a 100644
--- a/Ryujinx.Graphics.Vulkan/HelperShader.cs
+++ b/Ryujinx.Graphics.Vulkan/HelperShader.cs
@@ -4,6 +4,7 @@ using Ryujinx.Graphics.Shader.Translation;
 using Ryujinx.Graphics.Vulkan.Shaders;
 using Silk.NET.Vulkan;
 using System;
+using System.Collections.Generic;
 using VkFormat = Silk.NET.Vulkan.Format;
 
 namespace Ryujinx.Graphics.Vulkan
@@ -399,6 +400,86 @@ namespace Ryujinx.Graphics.Vulkan
                 newSize);
         }
 
+        public unsafe void ConvertIndexBuffer(VulkanRenderer gd,
+            CommandBufferScoped cbs,
+            BufferHolder src,
+            BufferHolder dst,
+            IndexBufferPattern pattern,
+            int indexSize,
+            int srcOffset,
+            int indexCount)
+        {
+            int convertedCount = pattern.GetConvertedCount(indexCount);
+            int outputIndexSize = 4;
+
+            // TODO: Do this with a compute shader?
+            var srcBuffer = src.GetBuffer().Get(cbs, srcOffset, indexCount * indexSize).Value;
+            var dstBuffer = dst.GetBuffer().Get(cbs, 0, convertedCount * outputIndexSize).Value;
+
+            gd.Api.CmdFillBuffer(cbs.CommandBuffer, dstBuffer, 0, Vk.WholeSize, 0);
+
+            var bufferCopy = new List<BufferCopy>();
+            int outputOffset = 0;
+
+            // Try to merge copies of adjacent indices to reduce copy count.
+            int sequenceStart = 0;
+            int sequenceLength = 0;
+
+            foreach (var index in pattern.GetIndexMapping(indexCount))
+            {
+                if (sequenceLength > 0)
+                {
+                    if (index == sequenceStart + sequenceLength && indexSize == outputIndexSize)
+                    {
+                        sequenceLength++;
+                        continue;
+                    }
+
+                    // Commit the copy so far.
+                    bufferCopy.Add(new BufferCopy((ulong)(srcOffset + sequenceStart * indexSize), (ulong)outputOffset, (ulong)(indexSize * sequenceLength)));
+                    outputOffset += outputIndexSize * sequenceLength;
+                }
+
+                sequenceStart = index;
+                sequenceLength = 1;
+            }
+
+            if (sequenceLength > 0)
+            {
+                // Commit final pending copy.
+                bufferCopy.Add(new BufferCopy((ulong)(srcOffset + sequenceStart * indexSize), (ulong)outputOffset, (ulong)(indexSize * sequenceLength)));
+            }
+
+            var bufferCopyArray = bufferCopy.ToArray();
+
+            BufferHolder.InsertBufferBarrier(
+                gd,
+                cbs.CommandBuffer,
+                dstBuffer,
+                BufferHolder.DefaultAccessFlags,
+                AccessFlags.AccessTransferWriteBit,
+                PipelineStageFlags.PipelineStageAllCommandsBit,
+                PipelineStageFlags.PipelineStageTransferBit,
+                0,
+                convertedCount * outputIndexSize);
+
+            fixed (BufferCopy* pBufferCopy = bufferCopyArray)
+            {
+                gd.Api.CmdCopyBuffer(cbs.CommandBuffer, srcBuffer, dstBuffer, (uint)bufferCopyArray.Length, pBufferCopy);
+            }
+
+            BufferHolder.InsertBufferBarrier(
+                gd,
+                cbs.CommandBuffer,
+                dstBuffer,
+                AccessFlags.AccessTransferWriteBit,
+                BufferHolder.DefaultAccessFlags,
+                PipelineStageFlags.PipelineStageTransferBit,
+                PipelineStageFlags.PipelineStageAllCommandsBit,
+                0,
+                convertedCount * outputIndexSize);
+        }
+
         protected virtual void Dispose(bool disposing)
         {
             if (disposing)
-- 
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