diff --git a/src/modules/stream/contours.cpp b/src/modules/stream/contours.cpp
index 9f37417..4e8e55a 100644
--- a/src/modules/stream/contours.cpp
+++ b/src/modules/stream/contours.cpp
@@ -1,4 +1,8 @@
+#undef NDEBUG
+#include <cassert>
 #include <core/object.h>
+#include <scene/3d/immediate_geometry.h>
+#include "wedge.h"
 #include "contours.h"
 
 Contours *Contours::singleton = nullptr;
@@ -11,6 +15,7 @@ Contours *Contours::get_singleton()
 }
 
 Contours::Contours()
+	: dbg(nullptr)
 {
 }
 
@@ -27,4 +32,247 @@ bool Contours::is_in_closed_contour(const struct wedge *w)
 			if (wedge_contours[i][j] == w)
 				return true;
 	return false;
-}
\ No newline at end of file
+}
+
+static Vector3 tangent(const Vector3 &v)
+{
+	Vector2 rv = Vector2(v.x, v.z).tangent();
+	return Vector3(rv.x, v.y, rv.y);
+}
+static Vector3 normal(const Vector3 &v)
+{
+	Vector3 rv = tangent(v);
+	rv.y = 0.0f;
+	return rv.normalized();
+}
+
+void Contours::build()
+{
+	int i, j;
+	contours.clear();
+	for (i = 0; i < (int)wedge_contours.size(); i++) {
+		struct main_contour mc;
+		for (j = 0; j < (int)wedge_contours[i].size(); j++) {
+			struct wedge *w = wedge_contours[i][j];
+			struct contour_wedge cw;
+			Vector3 d1 = (w->p[1] - w->p[0]).normalized();
+			Vector3 n1 = normal(d1);
+			Vector3 d2 = (w->p[2] - w->p[1]).normalized();
+			Vector3 n2 = normal(d2);
+			Vector3 m1 = n1 * (w->width1);
+			Vector3 m2 = n2 * (w->width2);
+			Vector3 dx = (d1 + d2).normalized();
+			Vector3 f1 = w->p[1] + m1;
+			Vector3 f2 = w->p[1] + m2;
+			Vector3 q, r;
+			Geometry::get_closest_points_between_segments(
+				w->p[0] + m1, f1, f2, w->p[2] + m2, q, r);
+			r = q.linear_interpolate(r, 0.5f);
+			cw.p[0] = w->p[0] + m1;
+			cw.p[1] = r;
+			cw.p[2] = w->p[2] + m2;
+			if (mc.aabb.size.is_equal_approx(Vector3()))
+				mc.aabb.position = cw.p[0];
+			else
+				mc.aabb.expand_to(cw.p[0]);
+			mc.aabb.expand_to(cw.p[1]);
+			mc.aabb.expand_to(cw.p[2]);
+			mc.points.push_back(cw.p[0]);
+			mc.points.push_back(cw.p[1]);
+			cw.wedge = w;
+			mc.contour_wedges.push_back(cw);
+		}
+		contours.push_back(mc);
+	}
+	polygons.clear();
+	for (i = 0; i < (int)contours.size(); i++)
+		polygons.push_back({ contours[i].points, contours[i].aabb });
+	List<struct polygon> polygon_queue;
+	List<struct polygon> polygon_output;
+	for (i = 0; i < (int)polygons.size(); i++)
+		polygon_queue.push_back(polygons[i]);
+	polygons.clear();
+	List<struct polygon>::Element *e = polygon_queue.front();
+	while (e) {
+		struct polygon item = e->get();
+		print_line("queue: " + itos(polygon_queue.size()));
+		polygon_queue.pop_front();
+		float area = item.area();
+		if (area > 120.0f * 120.0f && item.aabb.size.x > 10.0f &&
+		    item.aabb.size.z > 10.0f) {
+			std::pair<struct polygon, struct polygon> polys =
+				item.split();
+			if (polys.first.area() < 10.0f ||
+			    polys.second.area() < 10.0f) {
+				polygon_output.push_back(item);
+			} else {
+				polygon_queue.push_back(polys.first);
+				polygon_queue.push_back(polys.second);
+			}
+		} else
+			polygon_output.push_back(item);
+		e = polygon_queue.front();
+	}
+	polygons.reserve(polygon_output.size());
+	e = polygon_output.front();
+	while (e) {
+		polygons.push_back(e->get());
+		e = e->next();
+	}
+}
+
+void Contours::debug()
+{
+	int i, j;
+	if (!dbg) {
+		dbg = memnew(ImmediateGeometry);
+		SceneTree::get_singleton()->get_current_scene()->call_deferred(
+			"add_child", dbg);
+		if (!imm_mat.is_valid()) {
+			imm_mat.instance();
+			imm_mat->set_flag(
+				SpatialMaterial::FLAG_ALBEDO_FROM_VERTEX_COLOR,
+				true);
+			imm_mat->set_flag(
+				SpatialMaterial::FLAG_DISABLE_DEPTH_TEST, true);
+			imm_mat->set_flag(SpatialMaterial::FLAG_UNSHADED, true);
+		}
+		dbg->set_material_override(imm_mat);
+	}
+	dbg->clear();
+	dbg->begin(Mesh::PRIMITIVE_LINES);
+	dbg->set_color(Color(1, 1, 0, 1));
+	for (i = 0; i < (int)wedge_contours.size(); i++) {
+		for (j = 0; j < (int)wedge_contours[i].size(); j++) {
+			dbg->add_vertex(wedge_contours[i][j]->p[0] +
+					Vector3(0, 1, 0));
+			dbg->add_vertex(wedge_contours[i][j]->p[1] +
+					Vector3(0, 1, 0));
+			dbg->add_vertex(wedge_contours[i][j]->p[1] +
+					Vector3(0, 1, 0));
+			dbg->add_vertex(wedge_contours[i][j]->p[2] +
+					Vector3(0, 1, 0));
+		}
+	}
+	dbg->end();
+	dbg->begin(Mesh::PRIMITIVE_LINES);
+	dbg->set_color(Color(1, 1, 0.4f, 1));
+	for (i = 0; i < (int)polygons.size(); i++) {
+		for (j = 0; j < (int)polygons[i].points.size(); j++) {
+			dbg->add_vertex(polygons[i].points[j] +
+					Vector3(0, 2, 0));
+			dbg->add_vertex(
+				polygons[i].points[(j + 1) %
+						   polygons[i].points.size()] +
+				Vector3(0, 2, 0));
+		}
+	}
+	dbg->end();
+}
+
+std::pair<struct Contours::polygon, struct Contours::polygon>
+Contours::polygon::split() const
+{
+	int i, j;
+	float split_polygons_area = 0.0f;
+	float split_polygons_area_min = 0.0f;
+	std::pair<struct Contours::polygon, struct Contours::polygon>
+		split_polygons;
+	std::vector<int> edges;
+	for (i = 0; i < (int)points.size(); i++) {
+		Vector3 p0 = points[i];
+		Vector3 p1 = points[(i + 1) % points.size()];
+		if (p0.distance_squared_to(p1) > 100 * 100)
+			edges.push_back(i);
+	}
+	if (edges.size() == 0) {
+		for (i = 0; i < (int)points.size(); i++) {
+			Vector3 p0 = points[i];
+			Vector3 p1 = points[(i + 1) % points.size()];
+			edges.push_back(i);
+		}
+	}
+	for (i = 0; i < (int)edges.size(); i++) {
+		Vector3 p0 = points[edges[i]];
+		Vector3 p1 = points[(edges[i] + 1) % points.size()];
+		Transform xf =
+			Transform(Basis(), p0).looking_at(p1, Vector3(0, 1, 0));
+		AABB base;
+		base.position = xf.xform_inv(p0);
+		base.expand_to(xf.xform_inv(p1));
+		for (j = 0; j < (int)points.size(); j++)
+			base.expand_to(xf.xform_inv(points[j]));
+		Vector3 mpos0, mpos1;
+		if (base.size.x > base.size.z) {
+			mpos0 = base.position +
+				Vector3(base.size.x, 0, 0) * 0.5f;
+			mpos1 = mpos0 + Vector3(0, 0, base.size.z);
+			mpos0 = xf.xform(mpos0);
+			mpos1 = xf.xform(mpos1);
+		} else {
+			mpos0 = base.position +
+				Vector3(0, 0, base.size.z) * 0.5f;
+			mpos1 = mpos0 + Vector3(base.size.x, 0, 0);
+			mpos0 = xf.xform(mpos0);
+			mpos1 = xf.xform(mpos1);
+		}
+		mpos0.y = 0;
+		mpos1.y == 0;
+		/* mpos0 is at start of cut */
+
+		Vector3 n =
+			(mpos1 - mpos0).cross(Vector3(0, 1, 0)).normalized();
+		Plane pl1(mpos0 - n * 1.5f, n);
+		Plane pl2(mpos0 + n * 1.5f, -n);
+		Vector<Vector3> pdata;
+		pdata.resize(points.size());
+		memcpy(pdata.ptrw(), points.data(),
+		       points.size() * sizeof(Vector3));
+		struct polygon poly1, poly2;
+		Vector<Vector3> rpdata = Geometry::clip_polygon(pdata, pl1);
+		poly1.points.resize(rpdata.size());
+		memcpy(poly1.points.data(), rpdata.ptr(),
+		       rpdata.size() * sizeof(Vector3));
+		poly1.update_aabb();
+		rpdata = Geometry::clip_polygon(pdata, pl2);
+		poly2.points.resize(rpdata.size());
+		memcpy(poly2.points.data(), rpdata.ptr(),
+		       rpdata.size() * sizeof(Vector3));
+		poly2.update_aabb();
+		float area1 = poly1.area();
+		float area2 = poly2.area();
+		if (area1 <= 4.0f || area2 <= 4.0f)
+			continue;
+		float area_min = MIN(area1, area2);
+		float area = area1 + area2;
+		if (split_polygons_area_min < area_min &&
+		    split_polygons_area < area) {
+			split_polygons = { poly1, poly2 };
+			split_polygons_area_min = area_min;
+			split_polygons_area = area;
+		}
+	}
+	return split_polygons;
+}
+
+int Contours::polygon::longest_edge() const
+{
+	return 0;
+}
+
+void Contours::polygon::update_aabb()
+{
+	aabb = AABB();
+	int i;
+	for (i = 0; i < (int)points.size(); i++) {
+		if (aabb.is_equal_approx(AABB()))
+			aabb.position = points[i];
+		else
+			aabb.expand_to(points[i]);
+	}
+}
+
+float Contours::polygon::area() const
+{
+	return Geometry::find_polygon_area(points.data(), points.size());
+}
diff --git a/src/modules/stream/contours.h b/src/modules/stream/contours.h
index bc439bc..55fbdec 100644
--- a/src/modules/stream/contours.h
+++ b/src/modules/stream/contours.h
@@ -3,13 +3,37 @@
 #define CONTOURS_H_
 #include <vector>
 
+class ImmediateGeometry;
 struct Contours {
+	struct contour_wedge {
+		Vector3 p[3];
+		struct wedge *wedge;
+	};
+	struct main_contour {
+		std::vector<struct contour_wedge> contour_wedges;
+		std::vector<Vector3> points;
+		AABB aabb;
+	};
+	struct polygon {
+		std::vector<Vector3> points;
+		AABB aabb;
+		std::pair<struct polygon, struct polygon> split() const;
+		float area() const;
+		int longest_edge() const;
+		void update_aabb();
+	};
+	void build();
+	ImmediateGeometry *dbg;
+	Ref<SpatialMaterial> imm_mat;
 	std::vector<std::vector<struct wedge *> > wedge_contours;
+	std::vector<struct main_contour> contours;
+	std::vector<struct polygon> polygons;
 	static Contours *singleton;
 	static Contours *get_singleton();
 	Contours();
 	virtual ~Contours();
 	bool is_in_closed_contour(const struct wedge *w);
+	void debug();
 };
 
 #endif // CONTOURS_H_
\ No newline at end of file
diff --git a/src/modules/stream/road_processing.cpp b/src/modules/stream/road_processing.cpp
index 13ccb26..0354bc3 100644
--- a/src/modules/stream/road_processing.cpp
+++ b/src/modules/stream/road_processing.cpp
@@ -22,21 +22,9 @@
 #include "road_lines_data.h"
 #include "buildings_data.h"
 #include "contours.h"
+#include "wedge.h"
 #include "road_processing.h"
 
-struct side_ref {
-	String line_key;
-	int edge;
-	int side; // left = 0, right = 1
-};
-struct wedge {
-	Vector3 p[3];
-	Vector3 y[3];
-	int width1, width2;
-	struct side_ref side1_ref, side2_ref;
-	bool acute;
-};
-
 class DebugGeo : public ImmediateGeometry {
 	Ref<SpatialMaterial> imm_mat;
 	int vertex_count;
@@ -1245,6 +1233,8 @@ out_skip_end:;
 			if (base >= (int)wedges_ref.size())
 				break;
 		}
+		contours->build();
+		contours->debug();
 	}
 	~RoadLinesProcessing()
 	{
diff --git a/src/modules/stream/wedge.h b/src/modules/stream/wedge.h
new file mode 100644
index 0000000..8fd29dd
--- /dev/null
+++ b/src/modules/stream/wedge.h
@@ -0,0 +1,20 @@
+/* ~/godot-projects/streaming_world/src/modules/stream/wedge.h */
+#ifndef WEDGE_H_
+#define WEDGE_H_
+#include <core/math/vector3.h>
+#include <core/ustring.h>
+
+struct side_ref {
+	String line_key;
+	int edge;
+	int side; // left = 0, right = 1
+};
+struct wedge {
+	Vector3 p[3];
+	Vector3 y[3];
+	int width1, width2;
+	struct side_ref side1_ref, side2_ref;
+	bool acute;
+};
+
+#endif // WEDGE_H_
\ No newline at end of file