Fold: implement dynamic branching in shader

Switch from static branching approach using per-op data and fixed
execution order to dynamic branching approach using dynamic data.
This confers the main benefit of letting us dynamically reorder ops and
duplicate them. It also lets us eliminate some of the plumbing tedium
whenever we want to add new ops.

3 files changed, 56 insertions, 3 deletions

diff --git a/Scripts/Fold/Editor/FoldNodeSerialized.cs b/Scripts/Fold/Editor/FoldNodeSerialized.cs
index 4836811..62431ae 100644
--- a/Scripts/Fold/Editor/FoldNodeSerialized.cs
+++ b/Scripts/Fold/Editor/FoldNodeSerialized.cs
@@ -2,11 +2,15 @@ using UnityEngine;
 
 public class FoldNodeSerialized
 {
+  public int opcode;
+
+  // Correspond to _Vertex_Deformation_Float_0, etc.
   public float float0;
   public float float1;
   public float float2;
   public float float3;
 
+  // _Vertex_Deformation_Vector_0, etc.
   public Vector4 vec0;
   public Vector4 vec1;
   public Vector4 vec2;
diff --git a/Scripts/Fold/Editor/KeyframeNodeView.cs b/Scripts/Fold/Editor/KeyframeNodeView.cs
index fd90c75..225b5b6 100644
--- a/Scripts/Fold/Editor/KeyframeNodeView.cs
+++ b/Scripts/Fold/Editor/KeyframeNodeView.cs
@@ -2,6 +2,7 @@ using GraphProcessor;
 using UnityEngine.UIElements;
 using UnityEngine;
 using System.Linq;
+using System.Collections.Generic;
 
 [NodeCustomEditor(typeof(KeyframeNode))]
 public class KeyframeNodeView : BaseNodeView
@@ -25,10 +26,58 @@ public class KeyframeNodeView : BaseNodeView
     void OnGenerateClick()
     {
         var go = GetConnectedGameObject();
-        if (go?.GetComponent<MeshRenderer>() == null) return;
+        if (go == null) return;
+        var rend = go.GetComponent<MeshRenderer>();
+        if (rend == null) return;
 
         var foldNode = GetConnectedFoldNode();
-        Debug.Log($"Generating Keyframe for '{go.name}' using Fold Data: {(foldNode?.name ?? "None")}");
+
+        // Accumulate nodes. We are going backwards from the output node
+        // (KeyframeNode) to the root node.
+        var foldNodes = new Stack<BaseFoldNode>();
+        var cur = foldNode;
+        while (cur != null) {
+          foldNodes.Push(cur);
+          cur = GetInputFoldNode(cur);
+        }
+
+        var mpb = new MaterialPropertyBlock();
+        rend.GetPropertyBlock(mpb);
+
+        // Set material properties for all 16 slots.
+        for (int i = 0; i < 16; i++) {
+            string slotPrefix = $"_Vertex_Deformation_Slot_{i}_";
+            BaseFoldNode node = (foldNodes.Count > 0) ? foldNodes.Pop() : null;
+            FoldNodeSerialized data = node?.Serialize();
+
+            bool active = data != null;
+            mpb.SetFloat(slotPrefix + "Enabled", active ? 1.0f : 0.0f);
+            mpb.SetInt(slotPrefix + "Opcode", active ? data.opcode : 0);
+
+            mpb.SetFloat(slotPrefix + "Float_0", active ? data.float0 : 0.0f);
+            mpb.SetFloat(slotPrefix + "Float_1", active ? data.float1 : 0.0f);
+            mpb.SetFloat(slotPrefix + "Float_2", active ? data.float2 : 0.0f);
+            mpb.SetFloat(slotPrefix + "Float_3", active ? data.float3 : 0.0f);
+
+            mpb.SetVector(slotPrefix + "Vector_0", active ? data.vec0 : Vector4.zero);
+            mpb.SetVector(slotPrefix + "Vector_1", active ? data.vec1 : Vector4.zero);
+            mpb.SetVector(slotPrefix + "Vector_2", active ? data.vec2 : Vector4.zero);
+            mpb.SetVector(slotPrefix + "Vector_3", active ? data.vec3 : Vector4.zero);
+        }
+
+        rend.SetPropertyBlock(mpb);
+        Debug.Log($"Generated Keyframe for '{go.name}' with properties applied to all 16 slots.");
+    }
+
+    BaseFoldNode GetInputFoldNode(BaseFoldNode node)
+    {
+        // Traverse via edges in the graph model, as 'input' field might not be populated in Editor
+        var port = node.GetPort(nameof(BaseFoldNode.input), null);
+        if (port == null) return null;
+
+        // Find the edge connected to this input port
+        var edge = node.graph.edges.FirstOrDefault(e => e.inputPort == port);
+        return edge?.outputNode as BaseFoldNode;
     }
 
     T GetConnectedNode<T>(string fieldName) where T : class
diff --git a/Scripts/Fold/Editor/PointAlignNode.cs b/Scripts/Fold/Editor/PointAlignNode.cs
index 7ab094b..c113928 100644
--- a/Scripts/Fold/Editor/PointAlignNode.cs
+++ b/Scripts/Fold/Editor/PointAlignNode.cs
@@ -15,7 +15,7 @@ public class PointAlignNode : BaseFoldNode
 
   public override FoldNodeSerialized Serialize()
   {
-      return new FoldNodeSerialized { vec0 = po };
+      return new FoldNodeSerialized { opcode = 0, vec0 = po };
   }
 }