# UNDF: UNDF-2026-000000139
Fixes libgdx-0001/0002/0003: Model.loadNode / ModelBuilder.rebuildReferences /
ModelInstance.invalidate — O(N²) Array linear scans replaced with HashMap/IdentityHashMap.

--- a/gdx/src/com/badlogic/gdx/graphics/g3d/Model.java
+++ b/gdx/src/com/badlogic/gdx/graphics/g3d/Model.java

@@ DEFECT libgdx-0001: loadNode() — nested for-loop string-ID scan, O(parts × meshes + parts × materials)
@@ FIXME comment on line 188 already calls this out: "create temporary maps for faster lookup?"

 protected void loadNodes (Iterable<ModelNode> modelNodes) {
     nodePartBones.clear();
+    // FIX libgdx-0001: build lookup maps once before processing all nodes
+    Map<String, MeshPart> meshPartById = new java.util.HashMap<>();
+    for (int i = 0; i < meshParts.size; i++) {
+        MeshPart part = meshParts.get(i);
+        meshPartById.put(part.id, part);
+    }
+    Map<String, Material> materialById = new java.util.HashMap<>();
+    for (int i = 0; i < materials.size; i++) {
+        Material mat = materials.get(i);
+        materialById.put(mat.id, mat);
+    }
     for (ModelNode node : modelNodes) {
-        nodes.add(loadNode(node));
+        nodes.add(loadNode(node, meshPartById, materialById));
     }
     // ...bone transforms loop unchanged...
 }

-protected Node loadNode (ModelNode modelNode) {
+protected Node loadNode (ModelNode modelNode,
+        Map<String, MeshPart> meshPartById,
+        Map<String, Material> materialById) {
     Node node = new Node();
     node.id = modelNode.id;
     // ...translation/rotation/scale unchanged...
-    // FIXME create temporary maps for faster lookup?
+    // FIX libgdx-0001: maps provided by caller — O(1) lookups below
     if (modelNode.parts != null) {
         for (ModelNodePart modelNodePart : modelNode.parts) {
             MeshPart meshPart = null;
             Material meshMaterial = null;

             if (modelNodePart.meshPartId != null) {
-                for (MeshPart part : meshParts) {              // O(M) linear scan — CWE-407
-                    if (modelNodePart.meshPartId.equals(part.id)) {
-                        meshPart = part;
-                        break;
-                    }
-                }
+                meshPart = meshPartById.get(modelNodePart.meshPartId); // O(1)
             }

             if (modelNodePart.materialId != null) {
-                for (Material material : materials) {          // O(T) linear scan — CWE-407
-                    if (modelNodePart.materialId.equals(material.id)) {
-                        meshMaterial = material;
-                        break;
-                    }
-                }
+                meshMaterial = materialById.get(modelNodePart.materialId); // O(1)
             }
             // ...rest unchanged...
         }
     }
     if (modelNode.children != null) {
         for (ModelNode child : modelNode.children) {
-            node.addChild(loadNode(child));
+            node.addChild(loadNode(child, meshPartById, materialById));
         }
     }
     return node;
 }

--- a/gdx/src/com/badlogic/gdx/graphics/g3d/utils/ModelBuilder.java
+++ b/gdx/src/com/badlogic/gdx/graphics/g3d/utils/ModelBuilder.java

@@ DEFECT libgdx-0002: rebuildReferences() — Array.contains() in node-part loop, O(parts × materials)

+import java.util.IdentityHashMap;

 public static void rebuildReferences (final Model model) {
     model.materials.clear();
     model.meshes.clear();
     model.meshParts.clear();
+    // FIX libgdx-0002: identity sets for O(1) dedup instead of O(N) Array.contains()
+    IdentityHashMap<Material, Boolean> matSeen = new IdentityHashMap<>();
+    IdentityHashMap<MeshPart, Boolean> partSeen = new IdentityHashMap<>();
+    IdentityHashMap<Mesh, Boolean> meshSeen = new IdentityHashMap<>();
     for (final Node node : model.nodes)
-        rebuildReferences(model, node);
+        rebuildReferences(model, node, matSeen, partSeen, meshSeen);
 }

-private static void rebuildReferences (final Model model, final Node node) {
+private static void rebuildReferences (final Model model, final Node node,
+        IdentityHashMap<Material, Boolean> matSeen,
+        IdentityHashMap<MeshPart, Boolean> partSeen,
+        IdentityHashMap<Mesh, Boolean> meshSeen) {
     for (final NodePart mpm : node.parts) {
-        if (!model.materials.contains(mpm.material, true))  // O(M) CWE-407
+        if (matSeen.put(mpm.material, Boolean.TRUE) == null)  // O(1)
             model.materials.add(mpm.material);
-        if (!model.meshParts.contains(mpm.meshPart, true)) { // O(P) CWE-407
+        if (partSeen.put(mpm.meshPart, Boolean.TRUE) == null) { // O(1)
             model.meshParts.add(mpm.meshPart);
-            if (!model.meshes.contains(mpm.meshPart.mesh, true)) // O(X) CWE-407
+            if (meshSeen.put(mpm.meshPart.mesh, Boolean.TRUE) == null) // O(1)
                 model.meshes.add(mpm.meshPart.mesh);
             model.manageDisposable(mpm.meshPart.mesh);
         }
     }
     for (final Node child : node.getChildren())
-        rebuildReferences(model, child);
+        rebuildReferences(model, child, matSeen, partSeen, meshSeen);
 }

--- a/gdx/src/com/badlogic/gdx/graphics/g3d/ModelInstance.java
+++ b/gdx/src/com/badlogic/gdx/graphics/g3d/ModelInstance.java

@@ DEFECT libgdx-0003: invalidate() — Array.contains() in node-part loop, O(parts × materials)

+import java.util.IdentityHashMap;

-private void invalidate () {
+private void invalidate () {
+    // FIX libgdx-0003: identity set for O(1) dedup, avoids O(N²) Array.contains()
+    IdentityHashMap<Material, Boolean> seen = new IdentityHashMap<>();
     for (int i = 0, n = nodes.size; i < n; ++i) {
-        invalidate(nodes.get(i));
+        invalidate(nodes.get(i), seen);
     }
 }

-private void invalidate (Node node) {
+private void invalidate (Node node, IdentityHashMap<Material, Boolean> seen) {
     for (int i = 0, n = node.parts.size; i < n; ++i) {
         NodePart part = node.parts.get(i);
         ArrayMap<Node, Matrix4> bindPose = part.invBoneBindTransforms;
         if (bindPose != null) {
             for (int j = 0; j < bindPose.size; ++j) {
                 bindPose.keys[j] = getNode(bindPose.keys[j].id);
             }
         }
-        if (!materials.contains(part.material, true)) {      // O(T) CWE-407
+        if (!seen.containsKey(part.material)) {               // O(1)
             final int midx = materials.indexOf(part.material, false);
             if (midx < 0)
                 materials.add(part.material = part.material.copy());
             else
                 part.material = materials.get(midx);
+            seen.put(part.material, Boolean.TRUE);
         }
     }
     for (int i = 0, n = node.getChildCount(); i < n; ++i) {
-        invalidate(node.getChild(i));
+        invalidate(node.getChild(i), seen);
     }
 }