From eab96f208639c3c594a6a565970ac48bae2064eb Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Sun, 2 Jun 2024 11:01:23 +0200
Subject: [PATCH] Fix TAA jittering when rendering UI in world after TAA
 resolve

---
 Source/Engine/UI/UICanvas.cs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Source/Engine/UI/UICanvas.cs b/Source/Engine/UI/UICanvas.cs
index 0ddac70e1..0d8d79eb3 100644
--- a/Source/Engine/UI/UICanvas.cs
+++ b/Source/Engine/UI/UICanvas.cs
@@ -72,6 +72,7 @@ namespace FlaxEngine
             bounds.Transformation.Translation -= renderContext.View.Origin;
             if (renderContext.View.Frustum.Contains(bounds.GetBoundingBox()) == ContainmentType.Disjoint)
                 return;
+            var worldSpace = Canvas.RenderMode == CanvasRenderMode.WorldSpace || Canvas.RenderMode == CanvasRenderMode.WorldSpaceFaceCamera; 
 
             Profiler.BeginEvent("UI Canvas");
             Profiler.BeginEventGPU("UI Canvas");
@@ -79,14 +80,17 @@ namespace FlaxEngine
             // Calculate rendering matrix (world*view*projection)
             Canvas.GetWorldMatrix(renderContext.View.Origin, out Matrix worldMatrix);
             Matrix.Multiply(ref worldMatrix, ref renderContext.View.View, out Matrix viewMatrix);
-            Matrix.Multiply(ref viewMatrix, ref renderContext.View.Projection, out Matrix viewProjectionMatrix);
+            Matrix projectionMatrix = renderContext.View.Projection;
+            if (worldSpace && (Canvas.RenderLocation == PostProcessEffectLocation.Default || Canvas.RenderLocation == PostProcessEffectLocation.AfterAntiAliasingPass))
+                projectionMatrix = renderContext.View.NonJitteredProjection; // Fix TAA jittering when rendering UI in world after TAA resolve
+            Matrix.Multiply(ref viewMatrix, ref projectionMatrix, out Matrix viewProjectionMatrix);
 
             // Pick a depth buffer
             GPUTexture depthBuffer = Canvas.IgnoreDepth ? null : renderContext.Buffers.DepthBuffer;
 
             // Render GUI in 3D
             var features = Render2D.Features;
-            if (Canvas.RenderMode == CanvasRenderMode.WorldSpace || Canvas.RenderMode == CanvasRenderMode.WorldSpaceFaceCamera)
+            if (worldSpace)
                 Render2D.Features &= ~Render2D.RenderingFeatures.VertexSnapping;
             Render2D.CallDrawing(Canvas.GUI, context, input, depthBuffer, ref viewProjectionMatrix);
             Render2D.Features = features;