Creating an Explosive Drum with Collision Layers

This tutorial can of course be modified for other objects as well. However, the “explosive drum” idea is one that we surely all recognize from FPS's. This tutorial will deal with several concepts: collision layers, detection, and object death. For this tutorial, we will make two objects: the explosive drum and a bullet that will trigger it.

This will be the object that serves as the explosive drum.

sprite=drum.bmp
gravity=0.02
col_layer=1
health=100
on death()
 create_explosion(explosion1.exp)
 remove()

Note that we set the collision layer to 1. This means that if you specify another object to detect collision layer 1, then the drum will be affected. The on death() event specifies what will happen once the drum loses all its health.

This bullet will trigger the explosion.

gravity = 0.0009
repeat = 4
on detect_range(5,0,[1])
 damage(10)
 remove()
on detect_range(5,0,[worms,2])
 damage(15)
 remove()

Notice that we have two on detect_range events. The first is to specify what will happen once the bullet collides with collision layer 1; that is, the explosive drum. In this case, it will deal 10 damage to the drum. The second event is to specify what will happen if it collides with a worm or something in collision layer 2.

What if you don't want an object to be detected by a “detect all layers” event? Simple: set col_layer = -1. At this point, there are only 8 collision layers (0-7) and a worms layer.

Rather than using collision layers, you can use Custom Events.