From 422ad9e85b2ea9049c73b803067f8b9a80e25d26 Mon Sep 17 00:00:00 2001
From: Jason Ma <1312119064@qq.com>
Date: Wed, 7 Aug 2024 16:14:51 +0800
Subject: [PATCH] Separate LwguiGradient Alpha channel preview

---
 Runtime/LwguiGradient/LwguiGradient.cs        |  2 ++
 .../LwguiGradientEditorHelper.cs              | 25 ++++++++++++++++++-
 .../LwguiGradientPresetLibrary.cs             |  2 +-
 package.json                                  |  2 +-
 4 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/Runtime/LwguiGradient/LwguiGradient.cs b/Runtime/LwguiGradient/LwguiGradient.cs
index db81f04..ac019e0 100644
--- a/Runtime/LwguiGradient/LwguiGradient.cs
+++ b/Runtime/LwguiGradient/LwguiGradient.cs
@@ -39,6 +39,8 @@ public enum GradientTimeRange
             TwentyFour          = 24,
             TwentyFourHundred   = 2400
         }
+
+        public static bool HasChannelMask(ChannelMask channelMaskA, ChannelMask channelMaskB) => ((uint)channelMaskA & (uint)channelMaskB) > 0;
         
         public static bool IsChannelIndexInMask(int channelIndex, ChannelMask channelMask) => ((uint)channelMask & (uint)(1 << channelIndex)) > 0;
         
diff --git a/UnityEditorExtension/LwguiGradientEditor/LwguiGradientEditorHelper.cs b/UnityEditorExtension/LwguiGradientEditor/LwguiGradientEditorHelper.cs
index 6253426..fc76b00 100644
--- a/UnityEditorExtension/LwguiGradientEditor/LwguiGradientEditorHelper.cs
+++ b/UnityEditorExtension/LwguiGradientEditor/LwguiGradientEditorHelper.cs
@@ -42,6 +42,29 @@ public static void DrawGradientWithBackground(Rect position, LwguiGradient gradi
             // }
         }
 
+        public static void DrawGradientWithSeparateAlphaChannel(Rect position, LwguiGradient gradient, ColorSpace colorSpace, LwguiGradient.ChannelMask viewChannelMask)
+        {
+            if (!LwguiGradient.HasChannelMask(viewChannelMask, LwguiGradient.ChannelMask.Alpha) || viewChannelMask == LwguiGradient.ChannelMask.Alpha)
+            {
+                DrawGradientWithBackground(position, gradient, colorSpace, viewChannelMask);
+            }
+            else
+            {
+                var r2 = new Rect(position.x + 1, position.y + 1, position.width - 2, position.height - 2);
+                var rgbRect = new Rect(r2.x, r2.y, r2.width, r2.height * 0.8f);
+                var alphaRect = new Rect(rgbRect.x, rgbRect.yMax, r2.width, r2.height * 0.2f);
+                
+                var rgbTexture = gradient.GetPreviewRampTexture(256, 1, colorSpace, viewChannelMask ^ LwguiGradient.ChannelMask.Alpha);
+                var alphaTexture = gradient.GetPreviewRampTexture(256, 1, colorSpace, LwguiGradient.ChannelMask.Alpha);
+                
+                Color oldColor = GUI.color;
+                GUI.color = Color.white;            //Dont want the Playmode tint to be applied to gradient textures.
+                GUI.DrawTexture(rgbRect, rgbTexture, ScaleMode.StretchToFill, false);
+                GUI.DrawTexture(alphaRect, alphaTexture, ScaleMode.StretchToFill, false);
+                GUI.color = oldColor;
+            }
+        }
+
         public static void GradientField(Rect position, GUIContent label, LwguiGradient gradient, 
             ColorSpace colorSpace = ColorSpace.Gamma, 
             LwguiGradient.ChannelMask viewChannelMask = LwguiGradient.ChannelMask.All, 
@@ -85,7 +108,7 @@ public static void GradientField(Rect position, GUIContent label, LwguiGradient
 
                     break;
                 case EventType.Repaint:
-                    DrawGradientWithBackground(rect, gradient, colorSpace, viewChannelMask);
+                    DrawGradientWithSeparateAlphaChannel(rect, gradient, colorSpace, viewChannelMask);
                     break;
                 case EventType.ExecuteCommand:
                     // When drawing the modifying Gradient Field and it has changed
diff --git a/UnityEditorExtension/LwguiGradientEditor/LwguiGradientPresetLibrary.cs b/UnityEditorExtension/LwguiGradientEditor/LwguiGradientPresetLibrary.cs
index 6504e8f..d53cfb2 100644
--- a/UnityEditorExtension/LwguiGradientEditor/LwguiGradientPresetLibrary.cs
+++ b/UnityEditorExtension/LwguiGradientEditor/LwguiGradientPresetLibrary.cs
@@ -72,7 +72,7 @@ public void Draw(Rect rect, LwguiGradient gradient, ColorSpace colorSpace, Lwgui
         {
             if (gradient == null)
                 return;
-            LwguiGradientEditorHelper.DrawGradientWithBackground(rect, gradient, colorSpace, viewChannelMask);
+            LwguiGradientEditorHelper.DrawGradientWithSeparateAlphaChannel(rect, gradient, colorSpace, viewChannelMask);
         }
 
         public override string GetName(int index)
diff --git a/package.json b/package.json
index dc84727..6928163 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "com.jasonma.lwgui",
-  "version": "1.18.2",
+  "version": "1.18.3",
   "displayName": "LWGUI",
   "description": "A Lightweight, Flexible, Powerful Shader GUI System for Unity.",
   "keywords": [