diff --git a/core/src/bzh/fainsin/sagittarius/Arrow.java b/core/src/bzh/fainsin/sagittarius/Arrow.java
index 9761aa4..9a7e912 100644
--- a/core/src/bzh/fainsin/sagittarius/Arrow.java
+++ b/core/src/bzh/fainsin/sagittarius/Arrow.java
@@ -1,5 +1,7 @@
 package bzh.fainsin.sagittarius;
 
+import java.util.ArrayList;
+
 import com.badlogic.gdx.graphics.g2d.Batch;
 import com.badlogic.gdx.graphics.g2d.BitmapFont;
 import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
@@ -51,7 +53,7 @@ class Arrow extends Entity {
         if (!this.hasLanded()) {
             integrationVerlet(deltaTime);
             this.TTL -= deltaTime;
-            this.angle = this.velocity.angleRad();
+            this.angle = this.velocity.angleDeg();
         }
     }
 
@@ -61,6 +63,8 @@ class Arrow extends Entity {
 
             // TODO : vectorialiser
 
+            // System.out.println(deltaTime);
+
             this.acceleration = this.force.cpy();
 
             this.position.x += deltaTime * ( this.velocity.x + deltaTime * this.acceleration.x / 2 );
@@ -73,7 +77,7 @@ class Arrow extends Entity {
     }
 
     void render(ShapeRenderer shapeRenderer) {
-        Vector2 tail = new Vector2(-this.length, 0).rotateRad(this.angle).add(this.position);
+        Vector2 tail = new Vector2(-this.length, 0).rotateDeg(this.angle).add(this.position);
         shapeRenderer.line(this.position, tail);
     }
 
@@ -90,4 +94,27 @@ class Arrow extends Entity {
         }
     }
 
+// ---------- STATIC METHODs ----------
+
+    static float[] traj(float angle, float power, Player shooter, int iterations, float timeStep) {
+        ArrayList<Float> path = new ArrayList<Float>();
+        Arrow dummyArrow = new Arrow(angle, power, shooter);
+        for (int i = 0; i < iterations; i++) {
+            if (dummyArrow.hasLanded()) { break; }
+            dummyArrow.integrationVerlet(timeStep);
+            path.add(dummyArrow.position.x);
+            path.add(dummyArrow.position.y);
+        }
+
+        // TODO : optimize, lots of useless stuff
+
+        final float[] arr = new float[path.size()]; // TODO : min with 2, Exception in thread "main" java.lang.IllegalArgumentException: Polylines must contain at least 2 points.
+        int index = 0;
+        for (final Float value: path) {
+           arr[index++] = value;
+        }
+
+        return arr;
+    }
+
 }
diff --git a/core/src/bzh/fainsin/sagittarius/Bow.java b/core/src/bzh/fainsin/sagittarius/Bow.java
index f60c6fb..3a44162 100644
--- a/core/src/bzh/fainsin/sagittarius/Bow.java
+++ b/core/src/bzh/fainsin/sagittarius/Bow.java
@@ -56,7 +56,10 @@ class Bow {
     public void render(ShapeRenderer shapeRenderer) {
         if (pressed) {
             shapeRenderer.line(this.anchor, SagittariusGame.worldCursor);
-			//shapeRenderer.polyline(traj);
+            float[] traj = Arrow.traj(angle, power, shooter, 250, 0.05f);
+            if (traj.length > 2) {
+			    shapeRenderer.polyline(traj);
+            }
         }
 	}
 
diff --git a/core/src/bzh/fainsin/sagittarius/GameScreen.java b/core/src/bzh/fainsin/sagittarius/GameScreen.java
index f502eaa..8fdd20b 100644
--- a/core/src/bzh/fainsin/sagittarius/GameScreen.java
+++ b/core/src/bzh/fainsin/sagittarius/GameScreen.java
@@ -93,6 +93,9 @@ class GameScreen extends ScreenAdapter {
             arrow.render(shapeRenderer);
         }
 
+        // float[] vertices = {100, 100, 200, 200, 1000, 500};
+        // shapeRenderer.polyline(vertices);
+
         shapeRenderer.end();
 
         // HUD
diff --git a/core/src/bzh/fainsin/sagittarius/Player.java b/core/src/bzh/fainsin/sagittarius/Player.java
index 34e25b0..4327695 100644
--- a/core/src/bzh/fainsin/sagittarius/Player.java
+++ b/core/src/bzh/fainsin/sagittarius/Player.java
@@ -1,14 +1,12 @@
 package bzh.fainsin.sagittarius;
 
 import com.badlogic.gdx.Gdx;
-import com.badlogic.gdx.Input.Buttons;
 import com.badlogic.gdx.Input.Keys;
 import com.badlogic.gdx.graphics.g2d.Batch;
 import com.badlogic.gdx.graphics.g2d.BitmapFont;
 import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
 import com.badlogic.gdx.math.MathUtils;
 import com.badlogic.gdx.math.Vector2;
-import com.badlogic.gdx.scenes.scene2d.ui.Button;
 
 class Player extends Entity {