diff --git a/web/app/brep/geom/curve.js b/web/app/brep/geom/curve.js
index a39cfb17..2bd5779f 100644
--- a/web/app/brep/geom/curve.js
+++ b/web/app/brep/geom/curve.js
@@ -5,4 +5,11 @@ export class Curve {
 
   }
 
+  intersectCurve(curve) {
+    throw 'not implemented';
+  }
+  
+  parametricEquation(t) {
+    throw 'not implemented';
+  }
 }
\ No newline at end of file
diff --git a/web/app/brep/geom/impl/line.js b/web/app/brep/geom/impl/line.js
index c1438727..76893668 100644
--- a/web/app/brep/geom/impl/line.js
+++ b/web/app/brep/geom/impl/line.js
@@ -2,8 +2,43 @@ import {Curve} from '../curve'
 
 export class Line extends Curve {
 
-  constructor() {
+  constructor(p0, v) {
     super();
+    this.p0 = p0;
+    this.v = v;
   }
 
-}
\ No newline at end of file
+  intersectEdge(edge) {
+    throw 'not implemented';
+  }
+
+  intersectSurface(surface) {
+    //assume surface is plane
+    const s0 = surface.normal.multiply(surface.w);
+    return surface.normal(s0.minus(this.p0)) / surface.normal(this.v); // 4.7.4
+  }
+
+  intersectCurve(curve, surface) {
+    if (curve instanceof Line) {
+      const otherNormal = surface.normal.cross(curve.v)._normalize();
+      return otherNormal.dot(curve.p0.minus(this.p0)) / otherNormal.dot(this.v); // (4.8.3)    
+    }
+    return super.intersectCurve(curve);
+  }
+
+  parametricEquation(t) {
+    return this.p0.plus(this.v.multiply(t));
+  }
+}
+
+Line.fromTwoPlanesIntersection = function(plane1, plane2) {
+  const v = plane1.normal.cross(plane2.normal);
+  const plane1Vec = plane1.normal.multiply(plane1.w);
+  const plane2Vec = plane2.normal.multiply(plane2.w);
+  const p0 = plane1Vec.plus(plane2Vec);
+  return new Line(p0, v);
+};
+
+Line.fromSegment = function(a, b) {
+  return new Line(a, b.minus(a)._normalize());
+};
diff --git a/web/app/brep/geom/impl/plane.js b/web/app/brep/geom/impl/plane.js
index 214131a6..4d614aa7 100644
--- a/web/app/brep/geom/impl/plane.js
+++ b/web/app/brep/geom/impl/plane.js
@@ -1,4 +1,5 @@
 import {Surface} from '../surface'
+import {Line} from './line'
 import {AXIS} from  '../../../math/l3space'
  
 export class Plane extends Surface {
@@ -21,4 +22,12 @@ export class Plane extends Surface {
     x = y.cross(normal);
     return [x, y, normal];
   }
+  
+  intersect(other) {
+    if (other instanceof Plane) {
+      return new Line.fromTwoPlanesIntersection(this, other);
+    }
+    return super.intersect();
+  }
+  
 }
\ No newline at end of file
diff --git a/web/app/brep/geom/surface.js b/web/app/brep/geom/surface.js
index 423675f6..64ed3ad0 100644
--- a/web/app/brep/geom/surface.js
+++ b/web/app/brep/geom/surface.js
@@ -4,5 +4,9 @@ export class Surface {
   constructor() {
     
   }
+  
+  intersect() {
+    throw 'not implemented';
+  };
 
 }
\ No newline at end of file
diff --git a/web/app/brep/operations/boolean.js b/web/app/brep/operations/boolean.js
index af3c96d5..08606750 100644
--- a/web/app/brep/operations/boolean.js
+++ b/web/app/brep/operations/boolean.js
@@ -1,28 +1,28 @@
 import * as BREPBuilder from '../brep-builder';
-import {HalfEdge} from '../topo/edge';
+import {HalfEdge, Edge} from '../topo/edge';
 import {Loop} from '../topo/loop';
 import {Face} from '../topo/face';
 import {Shell} from '../topo/shell';
+import {Vertex} from '../topo/vertex';
+import {Line} from '../geom/impl/line';
+import Vector from '../../math/vector';
 
 export function union( shell1, shell2 ) {
+
   
-  const faces = shell1.faces.concat(shell2.faces);
+  const facesData = [];
   
-  const solveData = intersectFaces(shell1, shell2);
+  initSolveData(shell1, facesData);
+  initSolveData(shell2, facesData);
+  
+  intersectFaces(shell1, shell2);
 
   const result = new Shell();
   
-  for (let faceData of solveData.shell1.faceData) {
+  for (let faceData of facesData) {
     
     const seen = new Set();
 
-    //intersection edges must go first
-    faceData.edges.sort((a, b) => {
-      const aX = solveData.newEdges.has(a);
-      const bX = solveData.newEdges.has(b);
-      return aX ? (bX ? 0 : -1) : 1;
-    });
-    
     while (true) {
       let edge = faceData.edges.pop();
       if (edge == undefined || seen.has(edge)) {
@@ -32,7 +32,7 @@ export function union( shell1, shell2 ) {
       while (edge) {
         loop.halfEdges.push(edge);
         seen.add(edge);
-        let candidates = this.vertexToEdge.get(edge.vertexB);
+        let candidates = faceData.vertexToEdge.get(edge.vertexB);
         edge = findMaxTurningLeft(candidates);
         if (seen.has(edge)) {
           break;
@@ -48,37 +48,215 @@ export function union( shell1, shell2 ) {
   }
 }
 
-
-function intersectFaces(shell1, shell2) {
-  const data = new SolveData();
-  for (let i = 0; i < shell1.faces.length; i++) {
-    for (var j = 0; j < shell2.faces.length; j++) {
-      if (i == j) continue;
-      
-      const face1 = shell1.faces[i];
-      const face2 = shell2.faces[j];
-      const curve = face1.surface.intersect(face2.surface);
-
-      const face1Segments = split(curve, face1.outerLoop);
-      const face2Segments = split(curve, face2.outerLoop);
-      const segments = merge(face1Segments, face2Segments);        
-      
-      
+function initSolveData(shell, facesData) {
+  for (let face of shell.faces) {
+    const solveData = new FaceSolveData(face);
+    facesData.push(solveData);
+    face.__faceSolveData = solveData;
+    for (let he of face.outerLoop) {
+      EdgeSolveData.clear(he);
+      solveData.vertexToEdge.set(he.vertexA, [he]);
     }
-    
-  }
+  }  
+}
+
+function findMaxTurningLeft() {
   
 }
 
-class SolveData {
-  constructor() {
-    this.shell1 = new ShellSolveData();
-    this.shell2 = new ShellSolveData();
-    this.newEdges = new Set();
+function intersectFaces(shell1, shell2) {
+  for (let i = 0; i < shell1.faces.length; i++) {
+    for (let j = 0; j < shell2.faces.length; j++) {
+      const face1 = shell1.faces[i];
+      const face2 = shell2.faces[j];
+      
+      const curve = face1.surface.intersect(face2.surface);
+
+      const newEdges = [];
+      const direction = face1.surface.normal.cross(face2.surface.normal);
+      split(face2, face1.outerLoop, newEdges, curve, direction);
+      split(face1, face2.outerLoop, newEdges, curve, direction);
+
+      newEdges.forEach(e => {
+        face1.__faceSolveData.newEdges.push(e.halfEdge1);
+        addToListInMap(face1.__faceSolveData.vertexToEdge, e.halfEdge1.vertexA, e.halfEdge1);
+      });
+      newEdges.forEach(e =>  {
+        face2.__faceSolveData.newEdges.push(e.halfEdge2);
+        addToListInMap(face2.__faceSolveData.vertexToEdge, e.halfEdge2.vertexA, e.halfEdge2);
+      });
+    }
   }
 }
 
-class ShellSolveData  {
+function split(face, loop, result, onCurve, direction) {
+  const nodes = [];
+  for (let edge of loop.halfEdges) {
+    const edgeSolveData = EdgeSolveData.get(edge);
+    if (edgeSolveData.skipFace.has(face)) {
+      continue;
+    }
+    const preExistVertex = edgeSolveData.splitByFace.get(face);
+    if (preExistVertex) {
+      nodes.push(new Node(preExistVertex, edgeNormal(edge), edge));
+      continue
+    }
+    intersectSurfaceWithEdge(face.surface, edge, nodes);
+  }
+  for (let i = 0; i < nodes.length; i++) {
+    let inNode = nodes[i];
+    nodes[i] = null;
+    let closestIdx = findCloserProjection(nodes, inNode.point);
+    if (closestIdx == -1) {
+      throw 'consider me';
+    }
+    let outNode = nodes[closestIdx];
+    
+    if (outNode.normal.dot(inNode.normal) > 0) {
+      continue;
+    }
+
+    nodes[closestIdx] = null;
+    
+    const halfEdge1 = new HalfEdge();
+    halfEdge1.vertexA = inNode.vertex;
+    halfEdge1.vertexB = outNode.vertex;
+    
+    const halfEdge2 = new HalfEdge();
+    halfEdge2.vertexB = halfEdge1.vertexA;
+    halfEdge2.vertexA = halfEdge1.vertexB;
+
+    splitEdgeByVertex(inNode.edge, halfEdge1.vertexA);
+    splitEdgeByVertex(outNode.edge, halfEdge1.vertexB);
+
+    const sameDirection = direction.dot(outNode.point.minus(inNode.point)) > 0;
+
+    const halfEdgeSameDir = sameDirection ? halfEdge1 : halfEdge2;
+    const halfEdgeNegativeDir = sameDirection ? halfEdge2 : halfEdge1;
+
+    // cross edge should go with negative dir for the first face and positive for the second
+    const edge = new Edge(onCurve);
+    edge.halfEdge1 = halfEdgeNegativeDir;
+    edge.halfEdge2 = halfEdgeSameDir;
+    
+    result.push(edge);
+  }
+}
+
+function splitEdgeByVertex(originHalfEdge, vertex) {
+  const halfEdge1 = new HalfEdge();
+  halfEdge1.vertexA = vertex;
+  halfEdge1.vertexB = originHalfEdge.vertexB;
+
+  const halfEdge2 = new HalfEdge();
+  halfEdge2.vertexA = halfEdge1.vertexB;
+  halfEdge2.vertexB = halfEdge1.vertexA;
+
+  const newEdge = new Edge(originHalfEdge.edge);
+  BREPBuilder.linkHalfEdges(newEdge, halfEdge1, halfEdge2);
+
+  const twin = originHalfEdge.twin();
+  originHalfEdge.vertexB = vertex;
+  twin.vertexA = vertex;
+  
+  originHalfEdge.loop.push(halfEdge1);
+  twin.loop.push(halfEdge2);
+
+  halfEdge1.loop = originHalfEdge.loop;
+  halfEdge2.loop = twin.loop;
+
+  EdgeSolveData.transfer(originHalfEdge, halfEdge1);
+  EdgeSolveData.transfer(twin, halfEdge2);
+
+  EdgeSolveData.createIfEmpty(twin).splitByFace.set(originHalfEdge.loop.face, vertex);
+  EdgeSolveData.createIfEmpty(halfEdge2).skipFace.add(originHalfEdge.loop.face);
+
+  //addToListInMap(originHalfEdge.loop.face.__faceSolveData.vertexToEdge, 
+}
+
+function findCloserProjection(nodes, point) {
+  let hero = -1;
+  let heroDistance = Number.MAX_VALUE;
+  for (let i = 0; i < nodes.length; i++) {
+    let node = nodes[i];
+    if (node == null)
+    let projectionDistance = node.normal.dot(node.point.minus(point));
+    if (hero == -1 || (projectionDistance > 0 && projectionDistance < heroDistance)) {
+      hero = i;
+      heroDistance = projectionDistance;
+    }
+  }
+  return hero;
+}
+
+function intersectSurfaceWithEdge(surface, edge, result) {
+  const p0 = edge.vertexA.point;
+  const ab = edge.vertexB.point.minus(p0);
+  const length = ab.length();
+  const v = ab._multiply(1 / length);
+  const edgeLine = new Line(p0, v);
+  const t = edgeLine.intersectSurface(surface);
+  if (t >= 0 && t <= length) {
+    const pointOfIntersection = edgeLine.parametricEquation(t);
+    const edgeNormal = edge.loop.face.surface.normal.cross(v)._normalize() ;
+    result.push(new Node(new Vertex(pointOfIntersection), edgeNormal, edge));
+  }
+}
+
+function edgeNormal(edge) {
+  return edge.loop.face.surface.normal.cross( edge.vertexB.point.minus(edge.vertexA.point) )._normalize();
+}
+
+function intersectCurveWithEdge(curve, edge, surface, result) {
+  const p0 = edge.vertexA.point;
+  const ab = edge.vertexB.point.minus(p0);
+  const length = ab.length();
+  const v = ab._multiply(1 / length);
+  const edgeLine = new Line(p0, v);
+  const t = edgeLine.intersectCurve(curve, surface);
+  if (t >= 0 && t <= length) {
+    const pointOfIntersection = edgeLine.parametricEquation(t);
+    const edgeNormal = surface.normal.cross(v)._normalize() ;
+    result.push(new Node(pointOfIntersection, edgeNormal, edge));
+  }
+}
+
+function EdgeSolveData() {
+  this.splitByFace = new Map();
+  this.skipFace = new Set();
+}
+
+EdgeSolveData.EMPTY = new EdgeSolveData();
+
+EdgeSolveData.get = function(edge) {
+  if (!edge.__edgeSolveData) {
+    return EdgeSolveData.EMPTY;
+  }
+  return edge.__edgeSolveData;
+};
+
+EdgeSolveData.createIfEmpty = function(edge) {
+  if (!edge.__edgeSolveData) {
+    edge.__edgeSolveData = new EdgeSolveData();
+  }
+  return edge.__edgeSolveData;
+};
+
+EdgeSolveData.clear = function(edge) {
+  delete edge.__edgeSolveData;
+};
+
+EdgeSolveData.transfer = function(from, to) {
+  to.__edgeSolveData = from.__edgeSolveData;
+};
+
+function Node(vertex, normal, splitsEdge) {
+  this.vertex = vertex;
+  this.normal = normal;
+  this.point = vertex.point;
+}
+
+class SolveData {
   constructor() {
     this.faceData = [];
   }
@@ -87,7 +265,17 @@ class ShellSolveData  {
 class FaceSolveData {
   constructor(face) {
     this.face = face;
-    this.edges = [];
+    this.newEdges = [];
+    this.newChunks = [];
     this.vertexToEdge = new Map();
   }
 }
+
+function addToListInMap(map, key, value) {
+  let list = map.get(key);
+  if (!list) {
+    list = [];
+    map.set(key, list);
+  }
+  list.add(value);
+}