Forums » Help » Help With Finding Closest B Type | Homing Missiles

Hello:

I'm making a spaceship game and am thinking of
implementing a heat-seeking or homing missile type projectile.

Basically it will lock in and go after enemies with some efficacy.

I'm sort of just pooling for thoughts on how such a logic might
be implemented in this engine, if it is possible.

How might one entity (A type)
locate the closest entity (B type)
and move toward it?

I suppose a similar logic might be applied to
an NPC character on auto-fight mode.

My current thoughts involve creating a
grid of invisible entities,

perhaps 4 or 8, though surround and travel with the missiles.
If enemies of B type check against any entities on the grid,
the grid will shut off and the missile will redirect to that position.

That might work.
Any better ideas?

That's a great idea to cut down on the number of distance checks.

You could then use distanceTo on Entity to figure out which enemy is closest to the missle.

Thanks,
I'll look into that.

I did it with a single targeting entity
linked to multiple missile entities.

When the targeting entity checks against anything other than bullets,
the missile locks on the enemy position.

EntityTarget = ig.Entity.extend({
	size: {x: 160, y: 160},
	offset: {x: 0, y: 0},
	maxVel: {x: 5000, y: 5000},
	friction: {x: 200, y: 200},
	type: ig.Entity.TYPE.NONE,
	checkAgainst: ig.Entity.TYPE.B, // Check Against B
	collides: ig.Entity.COLLIDES.NEVER,
	missile:null,
	
	
	update: function() {

		//Kill me 
		if (ig.game.missile == false ) {
			this.kill();
		}
		if (this.missile == 1) {
			var theMissile = ig.game.getEntityByName('missile');
		}
		else if(this.missile == 2){
			var theMissile = ig.game.getEntityByName('missileTwo');
		}
		if (theMissile != undefined){
			this.pos.x = theMissile.pos.x - (theMissile.size.x * 2);
			this.pos.y = theMissile.pos.y - (theMissile.size.y * 2);
		}
		
		this.parent();
	},
	
	
	check: function( other ) {
		if (other.name != "bullet"){
			if (this.missile == 1) {
				var theMissile = ig.game.getEntityByName('missile');
			}
			else if(this.missile == 2){
				var theMissile = ig.game.getEntityByName('missileTwo');
			}
			if (theMissile != undefined){
				theMissile.locked = true;
				theMissile.lockedTimer.set(.3);
				var angle = theMissile.angleTo( other );
				theMissile.storedX = Math.cos(angle) * theMissile.speed;
				theMissile.storedY = Math.sin(angle) * theMissile.speed;
				this.kill();
			}
		}
	}	
});