Local project added

Assets/Scripts/VoxelOctree/GPU/OctreeGpuUpload.cs

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+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+
+// Layout for the GPU buffer: must match HLSL struct exactly and size-aligned.
+[StructLayout(LayoutKind.Sequential)]
+public struct LinearNode
+{
+    // ---- Bloc 1 (16 bytes)
+    public float penetrationFactor; // 4
+    public float reflexionFactor;   // 4
+    public uint childMask;          // 4
+    public int childBase;          // 4
+
+    // ---- Bloc 7 (16 bytes)
+    public uint isLeaf;             // 4
+    public uint isOccupied;         // 4
+    public uint pad0;               // 4
+    public uint pad1;               // 4
+}
+
+public struct LinearTree
+{
+    public LinearNode[] nodes;
+    public int rootIndex;
+}
+
+public static class OctreeGpuHelpers
+{
+    // Flatten the recursive octree into a linear array.
+    // Returns LinearNode[] and root index (should be 0)
+
+    public static LinearTree FlattenOctree(OctreeNode root)
+    {
+        nodeToSig = new Dictionary<OctreeNode, string>(ReferenceEqualityComparer<OctreeNode>.Default);
+        sigToIndex = new Dictionary<string, int>();
+
+        List<LinearNode> flatNodes = new List<LinearNode>();
+
+        flatNodes.Add(new LinearNode());
+        
+        int rootIndex = BuildNode(root, flatNodes, 0);
+
+        LinearTree linearTree;
+        linearTree.rootIndex = rootIndex;
+        linearTree.nodes = flatNodes.ToArray();
+
+        nodeToSig = null;
+
+        return linearTree;
+    }
+
+    private static Dictionary<OctreeNode, string> nodeToSig;
+    private static Dictionary<string, int> sigToIndex;
+
+    private static string ComputeChildrenSignature(OctreeNode node)
+    {
+        // child signatures
+        string[] childSigs = new string[8];
+        for (int i = 0; i < 8; i++)
+        {
+            var c = node.children[i];
+            childSigs[i] = c != null ? ComputeChildrenSignature(c) : "<null>";
+        }
+
+        // Build signature: combine node properties + child signatures (deterministic)
+        // Use StringBuilder then a hash (optional) — here we keep reasonable precision for floats
+        var sb = new StringBuilder();
+        sb.Append(node.isLeaf ? 'L' : 'N');
+        sb.Append(node.isOccupied ? '1' : '0');
+        sb.Append('|');
+        sb.Append(node.penetrationFactor.ToString("R")); // "R" for round-trip
+        sb.Append(',');
+        sb.Append(node.reflexionFactor.ToString("R"));
+        sb.Append('|');
+        for (int i = 0; i < 8; i++)
+        {
+            sb.Append(childSigs[i]);
+            sb.Append('|');
+        }
+
+        string sig = sb.ToString();
+        return sig;
+    }
+
+    // PASS 1: compute a stable signature for each node (string here for simplicity)
+    private static string ComputeSignature(OctreeNode node)
+    {
+        // child signatures
+        string[] childSigs = new string[8];
+        for (int i = 0; i < 8; i++)
+        {
+            var c = node.children[i];
+            childSigs[i] = c != null ? ComputeChildrenSignature(c) : "<null>";
+        }
+
+        // Build signature: combine node properties + child signatures (deterministic)
+        // Use StringBuilder then a hash (optional) — here we keep reasonable precision for floats
+        var sb = new StringBuilder();
+
+        for (int i = 0; i < 8; i++)
+        {
+            sb.Append(childSigs[i]);
+            sb.Append('|');
+        }
+
+        string sig = sb.ToString();
+        return sig;
+    }
+
+    // PASS 2: build nodes list — parent reserved first so unique children end up contiguous after parent.
+    private static int BuildNode(OctreeNode node, List<LinearNode> nodes, int nodeIndex)
+    {
+        LinearNode ln = nodes[nodeIndex];
+
+        // Now fill the LinearNode with correct fields.
+        ln.penetrationFactor = node.penetrationFactor;
+        ln.reflexionFactor = node.reflexionFactor;
+        ln.isLeaf = node.isLeaf ? 1u : 0u;
+        ln.isOccupied = node.isOccupied ? 1u : 0u;
+        ln.pad0 = 0;
+        ln.pad1 = 0;
+        ln.childMask = 0;
+
+        string sig = ComputeSignature(node);
+
+        if(sigToIndex.TryGetValue(sig, out int existingIndex))
+        {
+            ln.childBase = nodes[existingIndex].childBase;
+
+            for (int i = 0; i < 8; i++)
+            {
+                if (node.children[i] != null)
+                    ln.childMask |= (1u << i);
+            }
+
+            nodes[nodeIndex] = ln;
+            return nodeIndex;
+        }
+
+        ln.childBase = nodes.Count;
+
+        for (int i = 0; i < 8; i++)
+        {
+            OctreeNode childNode = node.children[i];
+            if (childNode != null)
+            {
+                nodes.Add(new LinearNode());
+            }
+        }
+
+        int realIndex = 0;
+        for (int i = 0; i < 8; i++)
+        {
+            OctreeNode childNode = node.children[i];
+            if (childNode != null)
+            {
+                int index = BuildNode(childNode, nodes, ln.childBase + realIndex);
+                string childSig = ComputeSignature(childNode);
+                sigToIndex[childSig] = index;
+
+                ln.childMask |= 1u << i;
+                realIndex++;
+            }
+        }
+
+        nodes[nodeIndex] = ln;
+
+        return nodeIndex;
+    }
+
+    // Simple reference-equality comparer for OctreeNode (so Dictionary uses node identity)
+    private class ReferenceEqualityComparer<T> : IEqualityComparer<T> where T : class
+    {
+        public static readonly ReferenceEqualityComparer<T> Default = new ReferenceEqualityComparer<T>();
+        public bool Equals(T x, T y) => ReferenceEquals(x, y);
+        public int GetHashCode(T obj) => System.Runtime.CompilerServices.RuntimeHelpers.GetHashCode(obj);
+    }
+}