From ae975506d78829de4080d8ca4ed85b9ed5c19c26 Mon Sep 17 00:00:00 2001
From: bd_ <bd_@nadena.dev>
Date: Sat, 19 Oct 2024 17:15:14 -0700
Subject: [PATCH] fix: occasionally objects controlling reactive components
 "flicker" (#1298)

Reported-by: @whipnice
---
 .../Animation/GameObjectDisableDelayPass.cs   | 45 +++++++++++++++++--
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/Editor/Animation/GameObjectDisableDelayPass.cs b/Editor/Animation/GameObjectDisableDelayPass.cs
index 8e8bca4c..fb453429 100644
--- a/Editor/Animation/GameObjectDisableDelayPass.cs
+++ b/Editor/Animation/GameObjectDisableDelayPass.cs
@@ -1,9 +1,11 @@
 using System.Linq;
+using nadena.dev.modular_avatar.core.editor;
 using nadena.dev.ndmf;
 using UnityEditor;
 using UnityEditor.Animations;
 using UnityEngine;
 using VRC.SDK3.Avatars.Components;
+using BuildContext = nadena.dev.ndmf.BuildContext;
 
 namespace nadena.dev.modular_avatar.animation
 {
@@ -23,11 +25,16 @@ namespace nadena.dev.modular_avatar.animation
 
             if (fx == null) return;
 
+            var nullMotion = new AnimationClip();
+            nullMotion.name = "NullMotion";
+            
             var blendTree = new BlendTree();
             blendTree.blendType = BlendTreeType.Direct;
             blendTree.useAutomaticThresholds = false;
 
-            blendTree.children = asc.BoundReadableProperties.Select(GenerateDelayChild).ToArray();
+            blendTree.children = asc.BoundReadableProperties
+                .Select(prop => GenerateDelayChild(nullMotion, prop))
+                .ToArray();
 
             var asm = new AnimatorStateMachine();
             var state = new AnimatorState();
@@ -54,7 +61,7 @@ namespace nadena.dev.modular_avatar.animation
             }).ToArray();
         }
 
-        private ChildMotion GenerateDelayChild((EditorCurveBinding, string) binding)
+        private ChildMotion GenerateDelayChild(Motion nullMotion, (EditorCurveBinding, string) binding)
         {
             var ecb = binding.Item1;
             var prop = binding.Item2;
@@ -64,10 +71,40 @@ namespace nadena.dev.modular_avatar.animation
             curve.AddKey(0, 1);
             AnimationUtility.SetEditorCurve(motion, ecb, curve);
 
+            // Occasionally, we'll have a very small value pop up, probably due to FP errors.
+            // To correct for this, instead of directly using the property in the direct blend tree,
+            // we'll use a 1D blend tree to give ourselves a buffer.
+
+            var bufferBlendTree = new BlendTree();
+            bufferBlendTree.blendType = BlendTreeType.Simple1D;
+            bufferBlendTree.useAutomaticThresholds = false;
+            bufferBlendTree.blendParameter = prop;
+            bufferBlendTree.children = new[]
+            {
+                new ChildMotion
+                {
+                    motion = nullMotion,
+                    timeScale = 1,
+                    threshold = 0
+                },
+                new ChildMotion
+                {
+                    motion = nullMotion,
+                    timeScale = 1,
+                    threshold = 0.01f
+                },
+                new ChildMotion
+                {
+                    motion = motion,
+                    timeScale = 1,
+                    threshold = 1
+                }
+            };
+
             return new ChildMotion
             {
-                motion = motion,
-                directBlendParameter = prop,
+                motion = bufferBlendTree,
+                directBlendParameter = MergeBlendTreePass.ALWAYS_ONE,
                 timeScale = 1
             };
         }