diff --git a/geometry/quad.cpp b/geometry/quad.cpp
index 44cac33..a908bf7 100644
--- a/geometry/quad.cpp
+++ b/geometry/quad.cpp
@@ -128,3 +128,7 @@ float Quad::surface() const {
 	Triangle sw(c[SE], c[SW], c[NW]);
 	return ne.surface() + sw.surface();
 }
+
+Quad Quad::offsetNormal(float offset) const {
+	return ((*this) + Triangle(c[NE], c[SE], c[SW]).normal().setNorm(offset));
+}
diff --git a/geometry/quad.hh b/geometry/quad.hh
index cad1b7b..61aa615 100644
--- a/geometry/quad.hh
+++ b/geometry/quad.hh
@@ -41,6 +41,7 @@ class Quad {
 	float surface() const;
 	//void cutCornerCorner(Coin from) const;
 	Quad makeParallelogram() const;
+	Quad offsetNormal(float offset) const;
 };
 
 
diff --git a/geometry/triangle.cpp b/geometry/triangle.cpp
index f44aea6..6b7f9e9 100644
--- a/geometry/triangle.cpp
+++ b/geometry/triangle.cpp
@@ -61,3 +61,12 @@ float Triangle::surface() const {
 	float base = Segment(c[LEFT], c[RIGHT]).length();
 	return (base * hauteur) / 2.f;
 }
+
+Vertex Triangle::normal() const {
+	return ((c[LEFT] - c[TOP]) * (c[RIGHT] - c[TOP]));
+}
+
+Vertex Triangle::normalizedNormal() const {
+	Vertex v = normal();
+	return v / v.norm();
+}
diff --git a/geometry/triangle.hh b/geometry/triangle.hh
index 8318f87..7672588 100644
--- a/geometry/triangle.hh
+++ b/geometry/triangle.hh
@@ -33,7 +33,8 @@ class Triangle {
 	Triangle inset(CoteTriangle side, float offset) const;
 	Triangle insetLTR(float offset) const;
 	Vertex randomPoint(int seed, int n) const;
-	void display();
+	Vertex normal() const;
+	Vertex normalizedNormal() const;
 };
 
 #endif
diff --git a/gputriangle.cpp b/gputriangle.cpp
index fcab260..28ddfbc 100644
--- a/gputriangle.cpp
+++ b/gputriangle.cpp
@@ -1,19 +1,14 @@
 #include "all_includes.hh"
 
 GPUTriangle::GPUTriangle(Vertex left, Vertex top, Vertex right, unsigned char _r, unsigned char _g, unsigned char _b)
-	: c(left, top, right), r(_r), g(_g), b(_b), vnormal(normal(left,top,right)) {
+	: c(left, top, right), r(_r), g(_g), b(_b), vnormal(c.normalizedNormal()) {
 }
 
 GPUTriangle::GPUTriangle(Triangle _c, unsigned char _r, unsigned char _g, unsigned char _b)
-	: c(_c), r(_r), g(_g), b(_b), vnormal(normal(c[LEFT], c[TOP], c[RIGHT])) {
+	: c(_c), r(_r), g(_g), b(_b), vnormal(c.normalizedNormal()) {
 }
 
-Vertex GPUTriangle::normal(Vertex left, Vertex top, Vertex right) {
-	Vertex v = (left - top)*(right - top);
-	return v / v.norm();
-}
-
-void GPUTriangle::display() {
+void GPUTriangle::display() const {
 	View::setColor(r,g,b);
 	glNormal3d(vnormal.x,vnormal.y,vnormal.z);
 	glVertex3d(c[LEFT].x,c[LEFT].y,c[LEFT].z);
@@ -21,7 +16,7 @@ void GPUTriangle::display() {
 	glVertex3d(c[RIGHT].x,c[RIGHT].y,c[RIGHT].z);
 }
 
-void GPUTriangle::displayNormal() {
+void GPUTriangle::displayNormal() const {
 	glColor3ub(255,255,0);
 	// Vertex v = (c[0] + c[1] + c[2]) / 3;
 	// glVertex3d(v.x,v.y,v.z);
diff --git a/gputriangle.hh b/gputriangle.hh
index 36fbdbf..31955c6 100644
--- a/gputriangle.hh
+++ b/gputriangle.hh
@@ -14,11 +14,8 @@ class GPUTriangle {
 public :
 	GPUTriangle(Vertex left, Vertex top, Vertex right, unsigned char r, unsigned char g, unsigned char b);
 	GPUTriangle(Triangle c, unsigned char r, unsigned char g, unsigned char b);
-	void display();
-	void displayNormal();
-
-private :
-	Vertex normal(Vertex left, Vertex top, Vertex right);
+	void display() const;
+	void displayNormal() const;
 };
 
 #endif
diff --git a/rules/quartier/quartiertri.cpp b/rules/quartier/quartiertri.cpp
index 1abe230..f4ee779 100644
--- a/rules/quartier/quartiertri.cpp
+++ b/rules/quartier/quartiertri.cpp
@@ -25,7 +25,7 @@ Chose* QuartierTri::factory(int seed, int n, Triangle c) {
 			return new QuartierTriTrapeze(c);
 		}
 	} else {
-		return new TerrainTriHerbe(c);
+		return new BatimentTri(c);
 	}
 }
 
diff --git a/rules/route/routequadchaussee.hh b/rules/route/routequadchaussee.hh
index 48af0ba..e3113bd 100644
--- a/rules/route/routequadchaussee.hh
+++ b/rules/route/routequadchaussee.hh
@@ -8,7 +8,7 @@ class RouteQuadChaussee : public Chose {
 	Quad c;
 
     public :
-	RouteQuadChaussee(Quad c);
+	RouteQuadChaussee(Quad _c);
 	virtual void triangulation();
 	virtual void getBoundingBoxPoints();
 };
diff --git a/rules/route/trottoirquadnormal.hh b/rules/route/trottoirquadnormal.hh
index ae1027d..98100b6 100644
--- a/rules/route/trottoirquadnormal.hh
+++ b/rules/route/trottoirquadnormal.hh
@@ -9,7 +9,7 @@ class TrottoirQuadNormal : public Chose {
 	float height;
 
 	public :
-	TrottoirQuadNormal(Quad c, float height);
+	TrottoirQuadNormal(Quad _c, float _height);
 	virtual void triangulation();
 	virtual void getBoundingBoxPoints();
 };
diff --git a/rules/terrain/terrainquadherbe.hh b/rules/terrain/terrainquadherbe.hh
index fd25165..b492be4 100644
--- a/rules/terrain/terrainquadherbe.hh
+++ b/rules/terrain/terrainquadherbe.hh
@@ -9,7 +9,7 @@ class TerrainQuadHerbe : public Chose {
 	Quad c;
 
     public :
-	TerrainQuadHerbe(Quad c);
+	TerrainQuadHerbe(Quad _c);
 	virtual void triangulation();
 	virtual void getBoundingBoxPoints();
 };
diff --git a/rules/terrain/terraintriherbe.hh b/rules/terrain/terraintriherbe.hh
index 51b9cb4..884972f 100644
--- a/rules/terrain/terraintriherbe.hh
+++ b/rules/terrain/terraintriherbe.hh
@@ -9,7 +9,7 @@ class TerrainTriHerbe : public Chose {
 	Triangle c;
 
     public :
-	TerrainTriHerbe(Triangle c);
+	TerrainTriHerbe(Triangle _c);
 	virtual void triangulation();
 	virtual void getBoundingBoxPoints();
 };