From 973af724f40ae8a5849243289511994c0b67b487 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Sun, 20 Dec 2020 00:03:14 +0100
Subject: [PATCH] Fix editor viewport camera glitch on first frame when using
 camera orbiting

---
 Source/Editor/Viewport/Cameras/FPSCamera.cs | 6 +++---
 Source/Editor/Viewport/EditorViewport.cs    | 9 +++++++++
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/Source/Editor/Viewport/Cameras/FPSCamera.cs b/Source/Editor/Viewport/Cameras/FPSCamera.cs
index 95ae37ffb..5058bbc19 100644
--- a/Source/Editor/Viewport/Cameras/FPSCamera.cs
+++ b/Source/Editor/Viewport/Cameras/FPSCamera.cs
@@ -160,8 +160,8 @@ namespace FlaxEditor.Viewport.Cameras
             if (IsAnimatingMove)
                 return;
 
-            EditorViewport.Input input;
-            Viewport.GetInput(out input);
+            Viewport.GetInput(out var input);
+            Viewport.GetPrevInput(out var prevInput);
             var mainViewport = Viewport as MainEditorGizmoViewport;
             bool isUsingGizmo = mainViewport != null && mainViewport.TransformGizmo.ActiveAxis != TransformGizmo.Axis.None;
 
@@ -202,7 +202,7 @@ namespace FlaxEditor.Viewport.Cameras
             }
 
             // Rotate or orbit
-            if (input.IsRotating || (input.IsOrbiting && !isUsingGizmo))
+            if (input.IsRotating || (input.IsOrbiting && !isUsingGizmo && prevInput.IsOrbiting))
             {
                 yaw += mouseDelta.X;
                 pitch += mouseDelta.Y;
diff --git a/Source/Editor/Viewport/EditorViewport.cs b/Source/Editor/Viewport/EditorViewport.cs
index 5b120f33f..42385fd5e 100644
--- a/Source/Editor/Viewport/EditorViewport.cs
+++ b/Source/Editor/Viewport/EditorViewport.cs
@@ -699,6 +699,15 @@ namespace FlaxEditor.Viewport
             input = _input;
         }
 
+        /// <summary>
+        /// Gets the input state data (from the previous update).
+        /// </summary>
+        /// <param name="input">The input.</param>
+        public void GetPrevInput(out Input input)
+        {
+            input = _prevInput;
+        }
+
         /// <summary>
         /// Creates the projection matrix.
         /// </summary>