only start preparing node reuse on the second build of a section

src/main/java/me/jellysquid/mods/sodium/client/render/chunk/translucent_sorting/bsp_tree/BSPWorkspace.java

@@ -20,9 +20,12 @@ class BSPWorkspace {
 
     final BSPResult result = new BSPResult();
 
-    BSPWorkspace(TQuad[] quads, ChunkSectionPos sectionPos) {
+    final boolean prepareNodeReuse;
+
+    BSPWorkspace(TQuad[] quads, ChunkSectionPos sectionPos, boolean prepareNodeReuse) {
         this.quads = quads;
         this.sectionPos = sectionPos;
+        this.prepareNodeReuse = prepareNodeReuse;
     }
 
     // TODO: better bidirectional triggering: integrate bidirectionality in GFNI if

src/main/java/me/jellysquid/mods/sodium/client/render/chunk/translucent_sorting/bsp_tree/InnerPartitionBSPNode.java

@@ -75,7 +75,7 @@ static NodeReuseData prepareNodeReuse(BSPWorkspace workspace, IntArrayList index
         // TODO: more sophisticated reuse scheduling (make uset configurable, and only
         // do once the section has been modified at least once already to avoid making
         // this data on terrain sections that are never touched)
-        if (depth == 1 && indexes.size() > NODE_REUSE_THRESHOLD) {
+        if (workspace.prepareNodeReuse && depth == 1 && indexes.size() > NODE_REUSE_THRESHOLD) {
             // collect the extents of the indexed quads and hash them
             var quadExtents = new float[indexes.size()][];
             int maxIndex = -1;

src/main/java/me/jellysquid/mods/sodium/client/render/chunk/translucent_sorting/data/BSPDynamicData.java

@@ -11,12 +11,16 @@
 import net.minecraft.util.math.ChunkSectionPos;
 
 public class BSPDynamicData extends DynamicData {
+    private static final int NODE_REUSE_MIN_GENERATION = 1;
+
     private final BSPNode rootNode;
+    private final int generation;
 
     private BSPDynamicData(ChunkSectionPos sectionPos,
-            NativeBuffer buffer, VertexRange range, BSPResult result) {
+            NativeBuffer buffer, VertexRange range, BSPResult result, int generation) {
         super(sectionPos, buffer, range, result);
         this.rootNode = result.getRootNode();
+        this.generation = generation;
     }
 
     @Override
@@ -34,16 +38,22 @@ public static BSPDynamicData fromMesh(BuiltSectionMeshParts translucentMesh,
             Vector3fc cameraPos, TQuad[] quads, ChunkSectionPos sectionPos,
             NativeBuffer buffer, TranslucentData oldData) {
         BSPNode oldRoot = null;
+        int generation = 0;
+        boolean prepareNodeReuse = false;
         if (oldData instanceof BSPDynamicData oldBSPData) {
+            generation = oldBSPData.generation + 1;
             oldRoot = oldBSPData.rootNode;
-        }
 
-        var result = BSPNode.buildBSP(quads, sectionPos, oldRoot);
+            // only enable partial updates after a certain number of generations
+            // (times the section has been built)
+            prepareNodeReuse = generation >= NODE_REUSE_MIN_GENERATION;
+        }
+        var result = BSPNode.buildBSP(quads, sectionPos, oldRoot, prepareNodeReuse);
 
         VertexRange range = TranslucentData.getUnassignedVertexRange(translucentMesh);
         buffer = PresentTranslucentData.nativeBufferForQuads(buffer, quads);
 
-        var dynamicData = new BSPDynamicData(sectionPos, buffer, range, result);
+        var dynamicData = new BSPDynamicData(sectionPos, buffer, range, result, generation);
         dynamicData.sort(cameraPos);
 
         // prepare accumulation groups for integration into GFNI triggering