# pymunk_demo_platformer_09.py Diff¶

pymunk_demo_platformer_09.py
```--- C:\Users\craven\Desktop\WebServer\arcade\doc\tutorials\pymunk_platformer\pymunk_demo_platformer_08.py
+++ C:\Users\craven\Desktop\WebServer\arcade\doc\tutorials\pymunk_platformer\pymunk_demo_platformer_09.py
@@ -64,6 +64,15 @@

# How many pixels to move before we change the texture in the walking animation
DISTANCE_TO_CHANGE_TEXTURE = 20
+
+# How much force to put on the bullet
+BULLET_MOVE_FORCE = 4500
+
+# Mass of the bullet
+BULLET_MASS = 0.1
+
+# Make bullet less affected by gravity
+BULLET_GRAVITY = 300

class PlayerSprite(arcade.Sprite):
""" Player Sprite """
@@ -276,6 +285,60 @@
self.left_pressed = False
elif key == arcade.key.RIGHT:
self.right_pressed = False
+
+    def on_mouse_press(self, x, y, button, modifiers):
+        """ Called whenever the mouse button is clicked. """
+
+        bullet = arcade.SpriteSolidColor(20, 5, arcade.color.DARK_YELLOW)
+        self.bullet_list.append(bullet)
+
+        # Position the bullet at the player's current location
+        start_x = self.player_sprite.center_x
+        start_y = self.player_sprite.center_y
+        bullet.position = self.player_sprite.position
+
+        # Get from the mouse the destination location for the bullet
+        # IMPORTANT! If you have a scrolling screen, you will also need
+        # to add in self.view_bottom and self.view_left.
+        dest_x = x
+        dest_y = y
+
+        # Do math to calculate how to get the bullet to the destination.
+        # Calculation the angle in radians between the start points
+        # and end points. This is the angle the bullet will travel.
+        x_diff = dest_x - start_x
+        y_diff = dest_y - start_y
+        angle = math.atan2(y_diff, x_diff)
+
+        # What is the 1/2 size of this sprite, so we can figure out how far
+        # away to spawn the bullet
+        size = max(self.player_sprite.width, self.player_sprite.height) / 2
+
+        # Use angle to to spawn bullet away from player in proper direction
+        bullet.center_x += size * math.cos(angle)
+        bullet.center_y += size * math.sin(angle)
+
+        # Set angle of bullet
+        bullet.angle = math.degrees(angle)
+
+        # Gravity to use for the bullet
+        # If we don't use custom gravity, bullet drops too fast, or we have
+        # to make it go too fast.
+        # Force is in relation to bullet's angle.
+        bullet_gravity = (0, -BULLET_GRAVITY)
+
+        # Add the sprite. This needs to be done AFTER setting the fields above.
+        self.physics_engine.add_sprite(bullet,
+                                       mass=BULLET_MASS,
+                                       damping=1.0,
+                                       friction=0.6,
+                                       collision_type="bullet",
+                                       gravity=bullet_gravity,
+                                       elasticity=0.9)
+
+        # Add force to bullet
+        force = (BULLET_MOVE_FORCE, 0)
+        self.physics_engine.apply_force(bullet, force)

def on_update(self, delta_time):
""" Movement and game logic """
```