diff --git a/core/src/sagittarius/model/Arrow.java b/core/src/sagittarius/model/Arrow.java
index b6f5d22..68fa99b 100644
--- a/core/src/sagittarius/model/Arrow.java
+++ b/core/src/sagittarius/model/Arrow.java
@@ -177,7 +177,7 @@ public class Arrow extends BaseActor {
         // TODO : optimize, lots of useless stuff + change name
         // or ignore and use adapters
 
-        final float[] arr = new float[path.size()];
+        final float[] arr = new float[path.size()]; // utiliser le count de la fonction, faire tab size iteration*2, et draw avec count
         int index = 0;
         for (final Float value: path) {
            arr[index++] = value;
diff --git a/core/src/sagittarius/model/Entity.java b/core/src/sagittarius/model/Entity.java
index 7d071d5..c738b97 100644
--- a/core/src/sagittarius/model/Entity.java
+++ b/core/src/sagittarius/model/Entity.java
@@ -1,18 +1,26 @@
 package sagittarius.model;
 
-import java.awt.Color;
-
-import com.badlogic.gdx.math.Vector;
+import com.badlogic.gdx.graphics.Color;
+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.graphics.glutils.ShapeRenderer.ShapeType;
+import com.badlogic.gdx.math.MathUtils;
+import com.badlogic.gdx.math.Polygon;
 import com.badlogic.gdx.math.Vector2;
+import com.badlogic.gdx.scenes.scene2d.Actor;
 
-public abstract class Entity {
+public abstract class Entity extends Actor {
 
 // ---------- ATTRIBUTEs ----------
 
+	protected static BitmapFont fontDebug = new BitmapFont();
+
+    protected Polygon hitbox = new Polygon(getHitbox());
+
 	protected float angle;
 	protected float mass;
 	protected Color color;
-
 	protected Vector2 position;
 
 // ---------- CONSTRUCTORs ----------
@@ -105,4 +113,30 @@ public abstract class Entity {
 	 */
 	protected abstract String getInfo();
 
+	/**
+	 * inpired from {@link ShapeRenderer#rect}
+	 * @return vertices of the hitbox polygon
+	 */
+	protected abstract float[] getHitbox();
+
+	@Override
+	public void act(float delta) {
+		super.act(delta);
+		hitbox.setVertices(getHitbox());
+	}
+
+    @Override
+    public void draw(Batch batch, float parentAlpha) {
+        super.draw(batch, parentAlpha);
+        if (getDebug()) fontDebug.draw(batch, getInfo(), getX(), getY());
+    }
+
+    @Override
+    protected void drawDebugBounds(ShapeRenderer shapes) {
+        if (!getDebug()) return;
+		shapes.set(ShapeType.Line);
+		if (getStage() != null) shapes.setColor(getStage().getDebugColor());
+		shapes.polygon(getHitbox());
+	}
+
 }
diff --git a/core/src/sagittarius/model/EntityCircle.java b/core/src/sagittarius/model/EntityCircle.java
new file mode 100644
index 0000000..a716dc0
--- /dev/null
+++ b/core/src/sagittarius/model/EntityCircle.java
@@ -0,0 +1,70 @@
+package sagittarius.model;
+
+import com.badlogic.gdx.graphics.Color;
+import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
+import com.badlogic.gdx.math.MathUtils;
+import com.badlogic.gdx.math.Vector2;
+
+public abstract class EntityCircle extends Entity {
+
+// ---------- ATTRIBUTEs ----------
+
+	protected float radius;
+
+// ---------- CONSTRUCTORs ----------
+
+	/** Creates an {@link #Entity}.
+	 * @param angle angle associated to the {@link #Entity}.
+	 * @param mass mass of the {@link #Entity}.
+	 * @param color color of the {@link #Entity}.
+	 * @param position position of the {@link #Entity}.
+	 */
+	public EntityCircle(float angle, float mass, Color color, Vector2 position, float radius) {
+		super(angle, mass, color, position);
+		this.radius = radius;
+	}
+
+// ---------- GETTERs ----------
+
+	/**
+	 * @return radius of the {@link #EntityCircle}.
+	 */
+	public float getRadius() {
+		return this.radius;
+	}
+
+// ---------- SETTERs ----------
+
+	/**
+	 * Sets the radius of the {@link #EntityCircle}.
+	 *
+	 * @param radius new radius.
+	 */
+	public void setRadius(float radius) {
+		this.radius = radius;
+	}
+// ---------- METHODs ----------
+
+	@Override
+	protected float[] getHitbox() {
+		int segments = Math.max(1, (int)(6 * (float)Math.cbrt(this.radius)));
+		float[] vertices = new float[2*segments]; 
+
+		float angle = 2 * MathUtils.PI / segments;
+		float cos = MathUtils.cos(angle);
+		float sin = MathUtils.sin(angle);
+		float cx = radius, cy = 0;
+
+		for (int i = 0; i < segments; i++) {
+			vertices[i] = this.position.x + cx;
+			vertices[i+1] = this.position.y + cy;
+
+			float temp = cx;
+			cx = cos * cx - sin * cy;
+			cy = sin * temp + cos * cy;
+		}
+
+		return vertices;
+	}
+
+}
diff --git a/core/src/sagittarius/model/EntityQuad.java b/core/src/sagittarius/model/EntityQuad.java
new file mode 100644
index 0000000..2f03060
--- /dev/null
+++ b/core/src/sagittarius/model/EntityQuad.java
@@ -0,0 +1,58 @@
+package sagittarius.model;
+
+import com.badlogic.gdx.graphics.Color;
+import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
+import com.badlogic.gdx.math.MathUtils;
+import com.badlogic.gdx.math.Vector2;
+
+public abstract class EntityQuad extends Entity {
+	
+// ---------- CONSTRUCTORs ----------
+
+	/** Creates an {@link #Entity}.
+	 * @param angle angle associated to the {@link #Entity}.
+	 * @param mass mass of the {@link #Entity}.
+	 * @param color color of the {@link #Entity}.
+	 * @param position position of the {@link #Entity}.
+	 */
+	public EntityQuad(float angle, float mass, Color color, Vector2 position) {
+		super(angle, mass, color, position);
+	}
+
+// ---------- METHODs ----------
+
+	@Override
+	protected float[] getHitbox() {
+		float cos = MathUtils.cosDeg(getRotation());
+		float sin = MathUtils.sinDeg(getRotation());
+		float fx = -getOriginX();
+		float fy = -getOriginY();
+		float fx2 = getWidth() - getOriginX();
+		float fy2 = getHeight() - getOriginY();
+
+		if (getScaleX() != 1 || getScaleX() != 1) {
+			fx *= getScaleX();
+			fy *= getScaleY();
+			fx2 *= getScaleX();
+			fy2 *= getScaleY();
+		}
+
+		float worldOriginX = this.position.x;
+		float worldOriginY = this.position.y;
+
+		float x1 = cos * fx - sin * fy + worldOriginX;
+		float y1 = sin * fx + cos * fy + worldOriginY;
+
+		float x2 = cos * fx2 - sin * fy + worldOriginX;
+		float y2 = sin * fx2 + cos * fy + worldOriginY;
+
+		float x3 = cos * fx2 - sin * fy2 + worldOriginX;
+		float y3 = sin * fx2 + cos * fy2 + worldOriginY;
+
+		float x4 = x1 + (x3 - x2);
+		float y4 = y3 - (y2 - y1);
+
+		return new float[] { x1, y1, x2, y2, x3, y3, x4, y4 };
+	}
+
+}