diff --git a/algoim/organizer/blobtree.hpp b/algoim/organizer/blobtree.hpp
index 7c89882..daab9a0 100644
--- a/algoim/organizer/blobtree.hpp
+++ b/algoim/organizer/blobtree.hpp
@@ -1,16 +1,19 @@
 #pragma once
 #include <vector>
+#include <cassert>
+#include <iostream>
 
 namespace algoim::organizer
 {
 // bitfield
 struct Blob {
-    unsigned int isPrimitive : 1; // 1 for leaf
-    unsigned int nodeOp      : 5; // 0 for intersection, 1 for union, 2 for difference
+    unsigned int isPrimitive   : 1; // 1 for leaf
+    unsigned int nodeOp        : 2; // 0 for union, 1 for intersection, 2 for difference
     // unsigned int ignoreMod   : 2; // 目前用不到
-    unsigned int inOut       : 2; // 0 for unknown, 1 for in, 2 for out
-    unsigned int isLeft      : 1;
-    unsigned int ancestor    : 23;
+    unsigned int inOut         : 2; // 0 for unknown, 1 for in, 2 for out
+    unsigned int oneChildInOut : 2; // 0 for unknown, 1 for in, 2 for out
+    unsigned int isLeft        : 1;
+    unsigned int ancestor      : 24;
 };
 
 bool isPrimitive(Blob b) { return b.isPrimitive == 1; }
@@ -19,36 +22,78 @@ unsigned int type(Blob b) { return 0; }
 
 bool isLeft(Blob b) { return b.isLeft == 1; }
 
-struct BlobTree {
-    std::vector<Blob> structure;
+class BlobTree
+{
+public:
+    std::vector<Blob>         structure;
+    std::vector<unsigned int> primtiveNodeIdx;
+
+    BlobTree() {}
 };
 
-void propagate(BlobTree &tree, unsigned int nodeIdx, bool in)
+void propagate(BlobTree& tree, unsigned int nodeIdx, bool in)
 {
     const std::size_t rootIdx = tree.structure.size() - 1;
+    auto&             node    = tree.structure[nodeIdx];
+    assert(node.inOut == 0);
+    node.inOut = in ? 1 : 2;
     for (unsigned int nowIdx = nodeIdx; nowIdx != rootIdx; ++nodeIdx) {
-        unsigned int nextIdx = isLeft(tree.structure[nowIdx]) ? tree.structure[nowIdx].ancestor : nodeIdx + 1;
-        if (tree.structure[nowIdx].inOut == 2) {
+        const auto&  nowNode  = tree.structure[nowIdx];
+        unsigned int nextIdx  = isLeft(nowNode) ? nowNode.ancestor : nodeIdx + 1;
+        auto&        nextNode = tree.structure[nextIdx];
+        if (nextNode.inOut != 0) { return; }
+        if (nowNode.inOut == 2) {
             // out
-            if (tree.structure[nextIdx].nodeOp == 0) {
+            if (nextNode.nodeOp == 1) {
                 // intersection
-                tree.structure[nextIdx].inOut = 2;
-                nextIdx                       = nowIdx;
-                continue;
-            } else if (tree.structure[nextIdx].nodeOp == 2 && isLeft(tree.structure[nowIdx])) {
-                // difference
-                tree.structure[nextIdx].inOut = 2;
-                nextIdx                       = nowIdx;
-                // continue;
+            } else if (nextNode.nodeOp == 2 && isLeft(nowNode)) {
+                // difference and left
+                nextNode.inOut = 2;
+            } else if (nextNode.oneChildInOut == 1) {
+                // 两种情况，Union: in, Difference: NowNode一定是right，in-out，还是in
+                nextNode.inOut = 1;
+            } else if (nextNode.oneChildInOut == 2) {
+                // 两种情况，Union: out, Difference: out-out, 还是out
+                nextNode.inOut = 2;
             } else {
+                nextNode.oneChildInOut = 2;
                 return;
             }
-        } else if (tree.structure[nowIdx].inOut == 1) {
+        } else if (nowNode.inOut == 1) {
             // in
-            // TODO:
+            if (nextNode.nodeOp == 0) {
+                // union
+                nextNode.inOut = 1;
+            } else if (nextNode.nodeOp == 2 && !isLeft(nowNode)) {
+                // difference and right
+                nextNode.inOut = 2;
+            } else if (nextNode.oneChildInOut == 1) {
+                // 两种情况，Intersection: in, Difference: in-in，out
+                nextNode.inOut = nextNode.nodeOp == 1 ? 1 : 2;
+            } else if (nextNode.oneChildInOut == 2) {
+                // 两种情况，Intersection: out, Difference: NowNode一定是left，in-out，in
+                nextNode.inOut = nextNode.nodeOp == 1 ? 2 : 1;
+            } else {
+                nextNode.oneChildInOut = 1;
+                return;
+            }
         }
+        nextIdx = nowIdx;
     }
     return;
 }
 
+// 这里传入的是拷贝，因为要修改，但不同traversal的修改不相互影响
+// TODO: 最好优化掉拷贝
+// TODO: std::vector<bool> 可以改成bitset之类
+bool traverse(BlobTree tree, std::vector<int> possiblePrimtivies, const std::vector<bool>& primitiveInout)
+{
+    assert(possiblePrimtivies.size() == tree.primtiveNodeIdx.size());
+    for (int nodeIdx : tree.primtiveNodeIdx) {
+        propagate(tree, nodeIdx, primitiveInout[]);
+        if (tree.structure.back().inOut != 0) { return tree.structure.back().inOut == 1; }
+    }
+    std::cerr << "should not be here" << std::endl;
+    return false;
+}
 }; // namespace algoim::organizer