Fix multi-threaded renderer in Godot 4.3

addons/imgui-godot/ImGuiGodot/Internal/RdRenderer.cs

@@ -294,7 +294,7 @@ protected void RenderOne(Rid fb, ImDrawDataPtr drawData)
         // allocate merged index and vertex buffers
         if (_idxBufferSize < drawData.TotalIdxCount)
         {
-            if (_idxBuffer.Id != 0)
+            if (_idxBuffer.IsValid)
                 RD.FreeRid(_idxBuffer);
             _idxBuffer = RD.IndexBufferCreate(
                 (uint)drawData.TotalIdxCount,
@@ -304,17 +304,17 @@ protected void RenderOne(Rid fb, ImDrawDataPtr drawData)
 
         if (_vtxBufferSize < drawData.TotalVtxCount)
         {
-            if (_vtxBuffer.Id != 0)
+            if (_vtxBuffer.IsValid)
                 RD.FreeRid(_vtxBuffer);
             _vtxBuffer = RD.VertexBufferCreate((uint)(drawData.TotalVtxCount * vertSize));
             _vtxBufferSize = drawData.TotalVtxCount;
         }
 
         // check if our font texture is still valid
-        foreach (var kv in _uniformSets)
+        foreach (var (texid, uniformSetRid) in _uniformSets)
         {
-            if (!RD.UniformSetIsValid(kv.Value))
-                _uniformSets.Remove(kv.Key);
+            if (!RD.UniformSetIsValid(uniformSetRid))
+                _uniformSets.Remove(texid);
         }
 
         if (drawData.CmdListsCount > 0)
@@ -396,9 +396,9 @@ public void Dispose()
     {
         RD.FreeRid(_sampler);
         RD.FreeRid(_shader);
-        if (_idxBuffer.Id != 0)
+        if (_idxBuffer.IsValid)
             RD.FreeRid(_idxBuffer);
-        if (_vtxBuffer.Id != 0)
+        if (_vtxBuffer.IsValid)
             RD.FreeRid(_vtxBuffer);
     }
 

addons/imgui-godot/ImGuiGodot/Internal/RdRendererThreadSafe.cs

@@ -57,9 +57,9 @@ public DisposableList(int capacity) : base(capacity) { }
 
     public void Dispose()
     {
-        foreach (var tuple in this)
+        foreach (var (_, u) in this)
         {
-            tuple.Item2.Dispose();
+            u.Dispose();
         }
         Clear();
     }
@@ -69,7 +69,41 @@ internal sealed class RdRendererThreadSafe : RdRenderer, IRenderer
 {
     public new string Name => "godot4_net_rd_mt";
 
-    private readonly object _sharedDataLock = new();
+#if GODOT4_3_OR_GREATER
+    public new void Render()
+    {
+        var pio = ImGui.GetPlatformIO();
+        var newData = new SharedList(pio.Viewports.Size);
+
+        for (int i = 0; i < pio.Viewports.Size; ++i)
+        {
+            var vp = pio.Viewports[i];
+            if (vp.Flags.HasFlag(ImGuiViewportFlags.IsMinimized))
+                continue;
+
+            Rid vprid = Util.ConstructRid((ulong)vp.RendererUserData);
+            newData.Add(new(vprid, new(vp.DrawData)));
+        }
+
+        RenderingServer.CallOnRenderThread(Callable.From(() => DrawOnRenderThread(newData)));
+    }
+
+    private void DrawOnRenderThread(SharedList dataArray)
+    {
+        foreach (var (vprid, clone) in dataArray)
+        {
+            Rid fb = GetFramebuffer(vprid);
+            if (RD.FramebufferIsValid(fb))
+            {
+                ReplaceTextureRids(clone.Data);
+                RenderOne(fb, clone.Data);
+            }
+        }
+
+        FreeUnusedTextures();
+        dataArray.Dispose();
+    }
+#else
     private SharedList? _dataToDraw;
 
     public RdRendererThreadSafe()
@@ -99,36 +133,30 @@ public RdRendererThreadSafe()
             newData.Add(new(GetFramebuffer(vprid), new(vp.DrawData)));
         }
 
-        lock (_sharedDataLock)
-        {
-            // if a frame was skipped, free old data
-            _dataToDraw?.Dispose();
-            _dataToDraw = newData;
-        }
+        // if a frame was skipped, free old data
+        var oldData = Interlocked.Exchange(ref _dataToDraw, newData);
+        oldData?.Dispose();
     }
 
     private SharedList TakeSharedData()
     {
-        lock (_sharedDataLock)
-        {
-            var rv = _dataToDraw;
-            _dataToDraw = null;
-            return rv ?? [];
-        }
+        var rv = Interlocked.Exchange(ref _dataToDraw, null);
+        return rv ?? [];
     }
 
     private void OnFramePreDraw()
     {
         // take ownership of shared data
         using SharedList dataArray = TakeSharedData();
 
-        foreach (var kv in dataArray)
+        foreach (var (fb, clone) in dataArray)
         {
-            if (RD.FramebufferIsValid(kv.Item1))
-                RenderOne(kv.Item1, kv.Item2.Data);
+            if (RD.FramebufferIsValid(fb))
+                RenderOne(fb, clone.Data);
         }
 
         FreeUnusedTextures();
     }
+#endif
 }
 #endif

addons/imgui-godot/ImGuiGodot/Widgets.cs

@@ -1,4 +1,3 @@
-#if GODOT_PC
 using Godot;
 using ImGuiNET;
 using System;
@@ -135,7 +134,7 @@ public static bool ImageButton(
         Vector4 bg_col,
         Vector4 tint_col)
     {
-        (Vector2 uv0, Vector2 uv1) = GetAtlasUVs(tex);
+        var (uv0, uv1) = GetAtlasUVs(tex);
         return ImGui.ImageButton(str_id, (IntPtr)tex.GetRid().Id, size, uv0, uv1, bg_col, tint_col);
     }
 
@@ -149,4 +148,7 @@ private static (Vector2 uv0, Vector2 uv1) GetAtlasUVs(AtlasTexture tex)
 #pragma warning restore IDE0004 // Remove Unnecessary Cast
     }
 }
+
+#if NET9_0_OR_GREATER
+// TODO: implicit extension GodotWidgets for ImGui
 #endif

gdext/src/RdRendererThreadSafe.cpp

@@ -1,5 +1,6 @@
 #include "RdRendererThreadSafe.h"
 #include "common.h"
+#include <godot_cpp/classes/display_server.hpp>
 #include <godot_cpp/classes/engine.hpp>
 #include <godot_cpp/classes/rendering_server.hpp>
 #include <mutex>
@@ -44,17 +45,33 @@ struct RdRendererThreadSafe::Impl
         ImDrawData* data;
     };
 
+    bool isGodot42 = false;
+
     using SharedData = std::pair<RID, std::unique_ptr<ClonedDrawData>>;
 
+    // mutex overhead should be minimal (near-zero contention), and refactoring to atomic is ugly
     std::mutex sharedDataMutex;
     std::vector<SharedData> dataToDraw;
 };
 
 RdRendererThreadSafe::RdRendererThreadSafe() : impl(std::make_unique<Impl>())
 {
-    RenderingServer* RS = RenderingServer::get_singleton();
-    RS->connect("frame_pre_draw",
-                Callable(Engine::get_singleton()->get_singleton("ImGuiController"), "on_frame_pre_draw"));
+    // TODO: remove 4.2 compatibility when 4.4 is released
+    Dictionary vinfo = Engine::get_singleton()->get_version_info();
+    impl->isGodot42 = (int)vinfo["hex"] < 0x040300;
+
+    if (impl->isGodot42)
+    {
+        RenderingServer* RS = RenderingServer::get_singleton();
+        RS->connect("frame_pre_draw",
+                    Callable(Engine::get_singleton()->get_singleton("ImGuiController"), "on_frame_pre_draw"));
+    }
+
+    if (DisplayServer::get_singleton()->window_get_vsync_mode() == DisplayServer::VSYNC_DISABLED)
+    {
+        UtilityFunctions::push_warning(
+            "[imgui-godot] Multi-threaded renderer with vsync disabled will probably crash");
+    }
 }
 
 RdRendererThreadSafe::~RdRendererThreadSafe()
@@ -72,16 +89,29 @@ void RdRendererThreadSafe::Render()
         if (vp->Flags & ImGuiViewportFlags_IsMinimized)
             continue;
 
-        ReplaceTextureRIDs(vp->DrawData);
         RID vprid = make_rid(vp->RendererUserData);
-        newData[i].first = GetFramebuffer(vprid);
+        if (impl->isGodot42)
+        {
+            ReplaceTextureRIDs(vp->DrawData);
+            newData[i].first = GetFramebuffer(vprid);
+        }
+        else
+        {
+            newData[i].first = vprid;
+        }
         newData[i].second = std::make_unique<Impl::ClonedDrawData>(vp->DrawData);
     }
 
     {
         std::unique_lock<std::mutex> lock(impl->sharedDataMutex);
         impl->dataToDraw = std::move(newData);
     }
+
+    if (!impl->isGodot42)
+    {
+        RenderingServer::get_singleton()->call_on_render_thread(
+            Callable(Engine::get_singleton()->get_singleton("ImGuiController"), "on_frame_pre_draw"));
+    }
 }
 
 void RdRendererThreadSafe::OnFramePreDraw()
@@ -95,10 +125,21 @@ void RdRendererThreadSafe::OnFramePreDraw()
     }
 
     RenderingDevice* RD = RenderingServer::get_singleton()->get_rendering_device();
-    for (auto& kv : dataArray)
+    for (const auto& kv : dataArray)
     {
-        if (RD->framebuffer_is_valid(kv.first))
-            RdRenderer::Render(kv.first, kv.second->data);
+        RID fb = kv.first;
+        ImDrawData* drawData = kv.second->data;
+
+        if (!impl->isGodot42)
+        {
+            fb = GetFramebuffer(fb);
+            ReplaceTextureRIDs(drawData);
+        }
+
+        if (RD->framebuffer_is_valid(fb))
+        {
+            RdRenderer::Render(fb, drawData);
+        }
     }
 
     FreeUnusedTextures();