From 1047911cfe613a3d67ca1224cfbf8e75675f9552 Mon Sep 17 00:00:00 2001
From: Chandler Cox <mr.chandlercox@gmail.com>
Date: Fri, 16 Aug 2024 07:40:52 -0500
Subject: [PATCH 1/2] Fix initial lerp jumping for Progress bar on first
 update.

---
 Source/Engine/UI/GUI/Common/ProgressBar.cs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Source/Engine/UI/GUI/Common/ProgressBar.cs b/Source/Engine/UI/GUI/Common/ProgressBar.cs
index 4852865bf..61e31b074 100644
--- a/Source/Engine/UI/GUI/Common/ProgressBar.cs
+++ b/Source/Engine/UI/GUI/Common/ProgressBar.cs
@@ -169,6 +169,9 @@ namespace FlaxEngine.GUI
         [EditorDisplay("Bar Style"), EditorOrder(2012), Tooltip("The brush used for progress bar drawing.")]
         public IBrush BarBrush { get; set; }
 
+        // Used to remove initial lerp from the value on play.
+        private bool _firstUpdate = true;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="ProgressBar"/> class.
         /// </summary>
@@ -202,7 +205,7 @@ namespace FlaxEngine.GUI
                 {
                     // Lerp or not if running slow
                     bool isDeltaSlow = deltaTime > (1 / 20.0f);
-                    if (!isDeltaSlow && UseSmoothing)
+                    if (!isDeltaSlow && UseSmoothing && !_firstUpdate)
                         value = Mathf.Lerp(_current, _value, Mathf.Saturate(deltaTime * 5.0f * SmoothingScale));
                     _current = value;
                 }
@@ -213,6 +216,9 @@ namespace FlaxEngine.GUI
             }
 
             base.Update(deltaTime);
+
+            if (_firstUpdate)
+                _firstUpdate = false;
         }
 
         /// <inheritdoc />

From 7772669148f44b9ac4b4f364f550f50f81a30fbd Mon Sep 17 00:00:00 2001
From: Chandler Cox <mr.chandlercox@gmail.com>
Date: Fri, 16 Aug 2024 07:46:31 -0500
Subject: [PATCH 2/2] Better fix.

---
 Source/Engine/UI/GUI/Common/ProgressBar.cs | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/Source/Engine/UI/GUI/Common/ProgressBar.cs b/Source/Engine/UI/GUI/Common/ProgressBar.cs
index 61e31b074..67f521c4a 100644
--- a/Source/Engine/UI/GUI/Common/ProgressBar.cs
+++ b/Source/Engine/UI/GUI/Common/ProgressBar.cs
@@ -143,9 +143,11 @@ namespace FlaxEngine.GUI
                 if (!Mathf.NearEqual(value, _value))
                 {
                     _value = value;
-                    if (!UseSmoothing)
+                    if (!UseSmoothing || _firstUpdate)
                     {
                         _current = _value;
+                        if (_firstUpdate)
+                            _firstUpdate = false;
                     }
                 }
             }
@@ -205,7 +207,7 @@ namespace FlaxEngine.GUI
                 {
                     // Lerp or not if running slow
                     bool isDeltaSlow = deltaTime > (1 / 20.0f);
-                    if (!isDeltaSlow && UseSmoothing && !_firstUpdate)
+                    if (!isDeltaSlow && UseSmoothing)
                         value = Mathf.Lerp(_current, _value, Mathf.Saturate(deltaTime * 5.0f * SmoothingScale));
                     _current = value;
                 }
@@ -216,9 +218,6 @@ namespace FlaxEngine.GUI
             }
 
             base.Update(deltaTime);
-
-            if (_firstUpdate)
-                _firstUpdate = false;
         }
 
         /// <inheritdoc />