Enemy Planes Flying

Create the enemy1 object. 

First add a Create event where it moving downwards with

• Vertical Speed 4.

Add a Step event. 

• Test Variable: if y > 512
  Checking if enemy plane gone past the bottom of the room, so
  480 (room height) + 32 (height of plane) = 512 
  has the plane gone past the bottom of the room?

• If so, Jump to Position: x = random(room_width), y = -16 
  so it starts above top of the room 

Change the room grid to 32x32.

Then 3-4 enemy1 planes in your room and test it out

• do they fly down when in the room?
• once they've gone out the bottom, do they reappear at the top?

We'll create a controller to keep creating enemy1 planes with a bit of delay.

Create a new object enemy 1 controller with no sprite. 

• Create event
• • Create Instance: enemy1 object,
    X = random(room_width) and Y = -16 
  • Alarm1 = 100

1. Duplicate the event for Alarm1 event
2. Then add a Test Instance Count action before the Alarm. If there are less than 8 of the enemy1 planes in the room, then we can set the alarm/timer to create more.

Put the enemy 1 controller object somewhere near the bottom of the room...

Also delete the enemy1 plane objects from the room.

Test out if it works. If it does, continue.

Start by duplicating enemy1 to create enemy2 - change the sprite for now.

Create a new object - enemy 2 controller - with no sprite.

• Create event
• • Create Instance: enemy2 object,
    X = random(room_width) and Y = -16 
  • Alarm2 = 200

1. Duplicate the event for Alarm2 event
2. Then add a Test Instance Count action before the Alarm. If there are less than 5 of the enemy2 planes in the room, then we can set the alarm/timer to create more.

To check that it works, go into your room and add enemy 2 controller object.

Duplicate the enemy1 object again to create enemy3. Change the name and sprite.

Create a new object enemy 3 controller with no sprite. 

• Create event
• • Create Instance: enemy3 object,
    X = random(room_width) and Y = -16 
  • Alarm3 = 300

1. Duplicate the event for Alarm2 event
2. Then add a Test Instance Count action before the Alarm. If there are less than 3 enemy3 planes in the room, then we can set the alarm/timer to create more.

Now add the enemy 3 controller to your room.

Test it out and make sure you see all 3 planes flying down.