From 835127ac21690d3e896dd12cbecc5f52dce79784 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Tue, 14 Feb 2023 12:39:58 +0100
Subject: [PATCH] Add **Animation Instance Data node to Anim Graph** for
 caching value per-model

---
 Source/Editor/Surface/Archetypes/Animation.cs      | 13 +++++++++++++
 Source/Engine/Animations/Graph/AnimGraph.Base.cpp  | 11 +++++++++--
 Source/Engine/Animations/Graph/AnimGraph.h         |  7 +++++++
 .../Animations/Graph/AnimGroup.Animation.cpp       | 14 +++++++++++++-
 4 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/Source/Editor/Surface/Archetypes/Animation.cs b/Source/Editor/Surface/Archetypes/Animation.cs
index dd214e8fc..b951f5f70 100644
--- a/Source/Editor/Surface/Archetypes/Animation.cs
+++ b/Source/Editor/Surface/Archetypes/Animation.cs
@@ -973,6 +973,19 @@ namespace FlaxEditor.Surface.Archetypes
                     NodeElementArchetype.Factory.TextBox(30, Surface.Constants.LayoutOffsetY, 140, TextBox.DefaultHeight, 0, false),
                 }
             },
+            new NodeArchetype
+            {
+                TypeID = 33,
+                Title = "Animation Instance Data",
+                Description = "Caches custom data per-instance and allow sampling it. Can be used to randomize animation play offset to offer randomization for crowds reusing the same graph.",
+                Flags = NodeFlags.AnimGraph,
+                Size = new Float2(240, 20),
+                Elements = new[]
+                {
+                    NodeElementArchetype.Factory.Output(0, "Get", typeof(Float4), 0),
+                    NodeElementArchetype.Factory.Input(0, "Init", true, typeof(Float4), 1),
+                }
+            },
         };
     }
 }
diff --git a/Source/Engine/Animations/Graph/AnimGraph.Base.cpp b/Source/Engine/Animations/Graph/AnimGraph.Base.cpp
index 3205337ad..d7cdbeecd 100644
--- a/Source/Engine/Animations/Graph/AnimGraph.Base.cpp
+++ b/Source/Engine/Animations/Graph/AnimGraph.Base.cpp
@@ -115,6 +115,11 @@ void SlotBucketInit(AnimGraphInstanceData::Bucket& bucket)
     bucket.Slot.LoopsLeft = 0;
 }
 
+void InstanceDataBucketInit(AnimGraphInstanceData::Bucket& bucket)
+{
+    bucket.InstanceData.Init = true;
+}
+
 bool SortMultiBlend1D(const byte& a, const byte& b, AnimGraphNode* n)
 {
     // Sort items by X location from the lowest to the highest
@@ -432,10 +437,12 @@ bool AnimGraphBase::onNodeLoaded(Node* n)
         }
         // Animation Slot
         case 32:
-        {
             ADD_BUCKET(SlotBucketInit);
             break;
-        }
+        // Animation Instance Data
+        case 33:
+            ADD_BUCKET(InstanceDataBucketInit);
+            break;
         }
         break;
     // Custom
diff --git a/Source/Engine/Animations/Graph/AnimGraph.h b/Source/Engine/Animations/Graph/AnimGraph.h
index 6f469dcb6..aeb91fbd0 100644
--- a/Source/Engine/Animations/Graph/AnimGraph.h
+++ b/Source/Engine/Animations/Graph/AnimGraph.h
@@ -315,6 +315,12 @@ public:
         int32 LoopsLeft;
     };
 
+    struct InstanceDataBucket
+    {
+        bool Init;
+        float Data[4];
+    };
+
     /// <summary>
     /// The single data storage bucket for the instanced animation graph node. Used to store the node state (playback position, state, transition data).
     /// </summary>
@@ -327,6 +333,7 @@ public:
             BlendPoseBucket BlendPose;
             StateMachineBucket StateMachine;
             SlotBucket Slot;
+            InstanceDataBucket InstanceData;
         };
     };
 
diff --git a/Source/Engine/Animations/Graph/AnimGroup.Animation.cpp b/Source/Engine/Animations/Graph/AnimGroup.Animation.cpp
index 9b74ff347..86aa42ff6 100644
--- a/Source/Engine/Animations/Graph/AnimGroup.Animation.cpp
+++ b/Source/Engine/Animations/Graph/AnimGroup.Animation.cpp
@@ -2035,10 +2035,22 @@ void AnimGraphExecutor::ProcessGroupAnimation(Box* boxBase, Node* nodeBase, Valu
         }
         break;
     }
+    // Animation Instance Data
+    case 33:
+    {
+        auto& bucket = context.Data->State[node->BucketIndex].InstanceData;
+        if (bucket.Init)
+        {
+            bucket.Init = false;
+            *(Float4*)bucket.Data = (Float4)tryGetValue(node->GetBox(1), Value::Zero);
+        }
+        value = *(Float4*)bucket.Data;
+        break;
+    }
     default:
         break;
     }
-    context.ValueCache.Add(boxBase, value);
+    context.ValueCache[boxBase] = value;
 }
 
 void AnimGraphExecutor::ProcessGroupFunction(Box* boxBase, Node* node, Value& value)