0ad/binaries/data/mods/public/simulation/components/Attack.js

function Attack() {}

var bonusesSchema = 
	"<optional>" +
		"<element name='Bonuses'>" +
			"<zeroOrMore>" +
				"<element>" +
					"<anyName/>" +
					"<interleave>" +
						"<optional>" +
							"<element name='Civ' a:help='If an entity has this civ then the bonus is applied'><text/></element>" +
						"</optional>" +
						"<element name='Classes' a:help='If an entity has all these classes then the bonus is applied'><text/></element>" +
						"<element name='Multiplier' a:help='The attackers attack strength is multiplied by this'><ref name='nonNegativeDecimal'/></element>" +
					"</interleave>" +
				"</element>" +
			"</zeroOrMore>" +
		"</element>" +
	"</optional>";

var preferredClassesSchema =
	"<optional>" +
		"<element name='PreferredClasses' a:help='Space delimited list of classes preferred for attacking. If an entity has any of theses classes, it is preferred. The classes are in decending order of preference.'>" +
			"<attribute name='datatype'>" +
				"<value>tokens</value>" +
			"</attribute>" +
			"<text/>" +
		"</element>" +
	"</optional>";

var restrictedClassesSchema =
	"<optional>" +
		"<element name='RestrictedClasses' a:help='Space delimited list of classes that cannot be attacked by this entity. If target entity has any of these classes, it cannot be attacked'>" +
			"<attribute name='datatype'>" +
				"<value>tokens</value>" +
			"</attribute>" +
			"<text/>" +
		"</element>" +
	"</optional>";

Attack.prototype.Schema =
	"<a:help>Controls the attack abilities and strengths of the unit.</a:help>" +
	"<a:example>" +
		"<Melee>" +
			"<Hack>10.0</Hack>" +
			"<Pierce>0.0</Pierce>" +
			"<Crush>5.0</Crush>" +
			"<MaxRange>4.0</MaxRange>" +
			"<RepeatTime>1000</RepeatTime>" +
			"<Bonuses>" +
				"<Bonus1>" +
					"<Civ>pers</Civ>" +
					"<Classes>Infantry</Classes>" +
					"<Multiplier>1.5</Multiplier>" +
				"</Bonus1>" +
				"<BonusCavMelee>" +
					"<Classes>Cavalry Melee</Classes>" +
					"<Multiplier>1.5</Multiplier>" +
				"</BonusCavMelee>" +
			"</Bonuses>" +
			"<RestrictedClasses datatype=\"tokens\">Champion</RestrictedClasses>" +
			"<PreferredClasses datatype=\"tokens\">Cavalry Infantry</PreferredClasses>" +
		"</Melee>" +
		"<Ranged>" +
			"<Hack>0.0</Hack>" +
			"<Pierce>10.0</Pierce>" +
			"<Crush>0.0</Crush>" +
			"<MaxRange>44.0</MaxRange>" +
			"<MinRange>20.0</MinRange>" +
			"<PrepareTime>800</PrepareTime>" +
			"<RepeatTime>1600</RepeatTime>" +
			"<ProjectileSpeed>50.0</ProjectileSpeed>" +
			"<Spread>2.5</Spread>" +
			"<Bonuses>" +
				"<Bonus1>" +
					"<Classes>Cavalry</Classes>" +
					"<Multiplier>2</Multiplier>" +
				"</Bonus1>" +
			"</Bonuses>" +
			"<RestrictedClasses datatype=\"tokens\">Champion</RestrictedClasses>" +
			"<Splash>" +
				"<Shape>Circular</Shape>" +
				"<Range>20</Range>" +
				"<FriendlyFire>false</FriendlyFire>" +
				"<Hack>0.0</Hack>" +
				"<Pierce>10.0</Pierce>" +
				"<Crush>0.0</Crush>" +
			"</Splash>" +
		"</Ranged>" +
		"<Charge>" +
			"<Hack>10.0</Hack>" +
			"<Pierce>0.0</Pierce>" +
			"<Crush>50.0</Crush>" +
			"<MaxRange>24.0</MaxRange>" +
			"<MinRange>20.0</MinRange>" +
		"</Charge>" +
	"</a:example>" +
	"<optional>" +
		"<element name='Melee'>" +
			"<interleave>" +
				"<element name='Hack' a:help='Hack damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='Pierce' a:help='Pierce damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='Crush' a:help='Crush damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='MaxRange' a:help='Maximum attack range (in metres)'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='RepeatTime' a:help='Time between attacks (in milliseconds). The attack animation will be stretched to match this time'>" + // TODO: it shouldn't be stretched
					"<data type='positiveInteger'/>" +
				"</element>" +
				bonusesSchema +
				preferredClassesSchema +
				restrictedClassesSchema +
			"</interleave>" +
		"</element>" +
	"</optional>" +
	"<optional>" +
		"<element name='Ranged'>" +
			"<interleave>" +
				"<element name='Hack' a:help='Hack damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='Pierce' a:help='Pierce damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='Crush' a:help='Crush damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='MaxRange' a:help='Maximum attack range (in metres)'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='MinRange' a:help='Minimum attack range (in metres)'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='PrepareTime' a:help='Time from the start of the attack command until the attack actually occurs (in milliseconds). This value relative to RepeatTime should closely match the \"event\" point in the actor&apos;s attack animation'>" +
					"<data type='nonNegativeInteger'/>" +
				"</element>" +
				"<element name='RepeatTime' a:help='Time between attacks (in milliseconds). The attack animation will be stretched to match this time'>" +
					"<data type='positiveInteger'/>" +
				"</element>" +
				"<element name='ProjectileSpeed' a:help='Speed of projectiles (in metres per second). If unspecified, then it is a melee attack instead'>" +
					"<ref name='nonNegativeDecimal'/>" +
				"</element>" +
				"<element name='Spread' a:help='Radius over which missiles will tend to land. Roughly 2/3 will land inside this radius (in metres)'><ref name='nonNegativeDecimal'/></element>" +
				bonusesSchema +
				preferredClassesSchema +
				restrictedClassesSchema +
				"<optional>" +
					"<element name='Splash'>" +
						"<interleave>" +
							"<element name='Shape' a:help='Shape of the splash damage, can be circular or linear'><text/></element>" +
							"<element name='Range' a:help='Size of the area affected by the splash'><ref name='nonNegativeDecimal'/></element>" +
							"<element name='FriendlyFire' a:help='Whether the splash damage can hurt non enemy units'><data type='boolean'/></element>" +
							"<element name='Hack' a:help='Hack damage strength'><ref name='nonNegativeDecimal'/></element>" +
							"<element name='Pierce' a:help='Pierce damage strength'><ref name='nonNegativeDecimal'/></element>" +
							"<element name='Crush' a:help='Crush damage strength'><ref name='nonNegativeDecimal'/></element>" +
							bonusesSchema +
						"</interleave>" +
					"</element>" +
				"</optional>" +
			"</interleave>" +
		"</element>" +
	"</optional>" +
	"<optional>" +
		"<element name='Charge'>" +
			"<interleave>" +
				"<element name='Hack' a:help='Hack damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='Pierce' a:help='Pierce damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='Crush' a:help='Crush damage strength'><ref name='nonNegativeDecimal'/></element>" +
				"<element name='MaxRange'><ref name='nonNegativeDecimal'/></element>" + // TODO: how do these work?
				"<element name='MinRange'><ref name='nonNegativeDecimal'/></element>" +
				bonusesSchema +
				preferredClassesSchema +
				restrictedClassesSchema +
			"</interleave>" +
		"</element>" +
	"</optional>";

Attack.prototype.Init = function()
{
};

Attack.prototype.Serialize = null; // we have no dynamic state to save

Attack.prototype.GetAttackTypes = function()
{
	var ret = [];
	if (this.template.Charge) ret.push("Charge");
	if (this.template.Melee) ret.push("Melee");
	if (this.template.Ranged) ret.push("Ranged");
	return ret;
};

Attack.prototype.GetPreferredClasses = function(type)
{
	if (this.template[type] && this.template[type].PreferredClasses)
	{
		return this.template[type].PreferredClasses._string.split(/\s+/);
	}
	return [];
};

Attack.prototype.GetRestrictedClasses = function(type)
{
	if (this.template[type] && this.template[type].RestrictedClasses)
	{
		return this.template[type].RestrictedClasses._string.split(/\s+/);
	}
	return [];
};

Attack.prototype.CanAttack = function(target)
{
	const cmpIdentity = Engine.QueryInterface(target, IID_Identity);
	if (!cmpIdentity) 
		return undefined;

	const targetClasses = cmpIdentity.GetClassesList();

	for each (var type in this.GetAttackTypes())
	{
		var canAttack = true;
		var restrictedClasses = this.GetRestrictedClasses(type);

		for each (var targetClass in targetClasses)
		{
			if (restrictedClasses.indexOf(targetClass) != -1)
			{
				canAttack = false;
				break;
			}
		}
		if (canAttack)
		{
			return true;
		}
	}

	return false;
};

/**
 * Returns null if we have no preference or the lowest index of a preferred class.
 */
Attack.prototype.GetPreference = function(target)
{
	const cmpIdentity = Engine.QueryInterface(target, IID_Identity);
	if (!cmpIdentity) 
		return undefined;

	const targetClasses = cmpIdentity.GetClassesList();
	
	var minPref = null;
	for each (var type in this.GetAttackTypes())
	{
		for each (var targetClass in targetClasses)
		{
			var pref = this.GetPreferredClasses(type).indexOf(targetClass);
			if (pref != -1 && (minPref === null || minPref > pref))
			{
				minPref = pref;
			}
		}
	}
	return minPref;
};

/**
 * Return the type of the best attack.
 * TODO: this should probably depend on range, target, etc,
 * so we can automatically switch between ranged and melee
 */
Attack.prototype.GetBestAttack = function()
{
	return this.GetAttackTypes().pop();
};

Attack.prototype.GetBestAttackAgainst = function(target)
{
	const cmpIdentity = Engine.QueryInterface(target, IID_Identity);
	if (!cmpIdentity) 
		return undefined;

	const targetClasses = cmpIdentity.GetClassesList();
	const isTargetClass = function (value, i, a) { return targetClasses.indexOf(value) != -1; };
	const types = this.GetAttackTypes();
	const attack = this;
	const isAllowed = function (value, i, a) { return !attack.GetRestrictedClasses(value).some(isTargetClass); }
	const isPreferred = function (value, i, a) { return attack.GetPreferredClasses(value).some(isTargetClass); }
	const byPreference = function (a, b) { return (types.indexOf(a) + (isPreferred(a) ? types.length : 0) ) - (types.indexOf(b) + (isPreferred(b) ? types.length : 0) ); }

	return types.filter(isAllowed).sort(byPreference).pop();
};

Attack.prototype.CompareEntitiesByPreference = function(a, b)
{
	var aPreference = this.GetPreference(a);
	var bPreference = this.GetPreference(b);

	if (aPreference === null && bPreference === null) return 0;
	if (aPreference === null) return 1;
	if (bPreference === null) return -1;
	return aPreference - bPreference;
};

Attack.prototype.GetTimers = function(type)
{
	var prepare = +(this.template[type].PrepareTime || 0);
	var repeat = +(this.template[type].RepeatTime || 1000);

	var cmpTechMan = QueryOwnerInterface(this.entity, IID_TechnologyManager);
	if (cmpTechMan)
	{
		prepare = cmpTechMan.ApplyModifications("Attack/" + type + "/PrepareTime", prepare, this.entity);
		repeat = cmpTechMan.ApplyModifications("Attack/" + type + "/RepeatTime", repeat, this.entity);
	}

	return { "prepare": prepare, "repeat": repeat, "recharge": repeat - prepare };
};

Attack.prototype.GetAttackStrengths = function(type)
{
	// Work out the attack values with technology effects
	var self = this;
	
	var template = this.template[type];
	var splash = "";
	if (!template)
	{
		template = this.template[type.split(".")[0]].Splash;
		splash = "/Splash";
	}
	
	var cmpTechMan = QueryOwnerInterface(this.entity, IID_TechnologyManager);
	var applyTechs = function(damageType)
	{
		var strength = +(template[damageType] || 0);
		if (cmpTechMan)
		{
			// All causes caching problems so disable it for now.
			//var allComponent = cmpTechMan.ApplyModifications("Attack/" + type + splash + "/All", strength, self.entity) - self.template[type][damageType];
			strength = cmpTechMan.ApplyModifications("Attack/" + type + splash + "/" + damageType, strength, self.entity);
		}
		return strength;
	};
	
	return {
		hack: applyTechs("Hack"),
		pierce: applyTechs("Pierce"),
		crush: applyTechs("Crush")
	};
};

Attack.prototype.GetRange = function(type)
{
	var max = +this.template[type].MaxRange;
	var min = +(this.template[type].MinRange || 0);

	var cmpTechMan = QueryOwnerInterface(this.entity, IID_TechnologyManager);
	if (cmpTechMan)
	{
		max = cmpTechMan.ApplyModifications("Attack/" + type + "/MaxRange", max, this.entity);
		min = cmpTechMan.ApplyModifications("Attack/" + type + "/MinRange", min, this.entity);
	}
	
	return { "max": max, "min": min };
};

// Calculate the attack damage multiplier against a target
Attack.prototype.GetAttackBonus = function(type, target)
{
	var attackBonus = 1;
	var template = this.template[type];
	if (!template)
		template = this.template[type.split(".")[0]].Splash;
	
	if (template.Bonuses)
	{
		var cmpIdentity = Engine.QueryInterface(target, IID_Identity);
		if (!cmpIdentity)
			return 1;
		
		// Multiply the bonuses for all matching classes
		for (var key in template.Bonuses)
		{
			var bonus = template.Bonuses[key];
			
			var hasClasses = true;
			if (bonus.Classes){
				var classes = bonus.Classes.split(/\s+/);
				for (var key in classes)
					hasClasses = hasClasses && cmpIdentity.HasClass(classes[key]);
			}
			
			if (hasClasses && (!bonus.Civ || bonus.Civ === cmpIdentity.GetCiv()))
				attackBonus *= bonus.Multiplier;
		}
	}
	
	return attackBonus;
};

// Returns a 2d random distribution scaled for a spread of scale 1.
// The current implementation is a 2d gaussian with sigma = 1
Attack.prototype.GetNormalDistribution = function(){
	
	// Use the Box-Muller transform to get a gaussian distribution
	var a = Math.random();
	var b = Math.random();
	
	var c = Math.sqrt(-2*Math.log(a)) * Math.cos(2*Math.PI*b);
	var d = Math.sqrt(-2*Math.log(a)) * Math.sin(2*Math.PI*b);
	
	return [c, d];
};

/**
 * Attack the target entity. This should only be called after a successful range check,
 * and should only be called after GetTimers().repeat msec has passed since the last
 * call to PerformAttack.
 */
Attack.prototype.PerformAttack = function(type, target)
{
	// If this is a ranged attack, then launch a projectile
	if (type == "Ranged")
	{
		// In the future this could be extended:
		//  * Obstacles like trees could reduce the probability of the target being hit
		//  * Obstacles like walls should block projectiles entirely

		// Get some data about the entity
		var horizSpeed = +this.template[type].ProjectileSpeed;
		var gravity = 9.81; // this affects the shape of the curve; assume it's constant for now
		
		var spread = this.template.Ranged.Spread;
		
		//horizSpeed /= 2; gravity /= 2; // slow it down for testing
		
		var cmpPosition = Engine.QueryInterface(this.entity, IID_Position);
		if (!cmpPosition || !cmpPosition.IsInWorld())
			return;
		var selfPosition = cmpPosition.GetPosition();
		var cmpTargetPosition = Engine.QueryInterface(target, IID_Position);
		if (!cmpTargetPosition || !cmpTargetPosition.IsInWorld())
			return;
		var targetPosition = cmpTargetPosition.GetPosition();
		
		var relativePosition = {"x": targetPosition.x - selfPosition.x, "z": targetPosition.z - selfPosition.z}
		var previousTargetPosition = Engine.QueryInterface(target, IID_Position).GetPreviousPosition();
		
		var targetVelocity = {"x": (targetPosition.x - previousTargetPosition.x) / this.turnLength, "z": (targetPosition.z - previousTargetPosition.z) / this.turnLength}
		// the component of the targets velocity radially away from the archer
		var radialSpeed = this.VectorDot(relativePosition, targetVelocity) / this.VectorLength(relativePosition);
		
		var horizDistance = this.VectorDistance(targetPosition, selfPosition);
		
		// This is an approximation of the time ot the target, it assumes that the target has a constant radial 
		// velocity, but since units move in straight lines this is not true.  The exact value would be more 
		// difficult to calculate and I think this is sufficiently accurate.  (I tested and for cavalry it was 
		// about 5% of the units radius out in the worst case)
		var timeToTarget = horizDistance / (horizSpeed - radialSpeed);
		
		// Predict where the unit is when the missile lands.
		var predictedPosition = {"x": targetPosition.x + targetVelocity.x * timeToTarget,
		                         "z": targetPosition.z + targetVelocity.z * timeToTarget};
		
		// Compute the real target point (based on spread and target speed)
		var randNorm = this.GetNormalDistribution();
		var offsetX = randNorm[0] * spread * (1 + this.VectorLength(targetVelocity) / 20);
		var offsetZ = randNorm[1] * spread * (1 + this.VectorLength(targetVelocity) / 20);

		var realTargetPosition = { "x": predictedPosition.x + offsetX, "y": targetPosition.y, "z": predictedPosition.z + offsetZ };
		
		// Calculate when the missile will hit the target position
		var realHorizDistance = this.VectorDistance(realTargetPosition, selfPosition);
		var timeToTarget = realHorizDistance / horizSpeed;
		
		var missileDirection = {"x": (realTargetPosition.x - selfPosition.x) / realHorizDistance, "z": (realTargetPosition.z - selfPosition.z) / realHorizDistance};
		
		// Make the arrow appear to land slightly behind the target so that arrows landing next to a guys foot don't count but arrows that go through the torso do
		var graphicalPosition = {"x": realTargetPosition.x + 2*missileDirection.x, "y": realTargetPosition.y + 2*missileDirection.y};
		// Launch the graphical projectile
		var cmpProjectileManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_ProjectileManager);
		var id = cmpProjectileManager.LaunchProjectileAtPoint(this.entity, realTargetPosition, horizSpeed, gravity);
		
		var cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
 		cmpTimer.SetTimeout(this.entity, IID_Attack, "MissileHit", timeToTarget*1000, {"type": type, "target": target, "position": realTargetPosition, "direction": missileDirection, "projectileId": id});
	}
	else
	{
		// Melee attack - hurt the target immediately
		this.CauseDamage({"type": type, "target": target});
	}
	// TODO: charge attacks (need to design how they work)
};

/**
 * Called when some units kills something (another unit, building, animal etc)
 */
Attack.prototype.TargetKilled = function(killerEntity, targetEntity)
{
	var cmpKillerPlayerStatisticsTracker = QueryOwnerInterface(killerEntity, IID_StatisticsTracker);
	if (cmpKillerPlayerStatisticsTracker) cmpKillerPlayerStatisticsTracker.KilledEntity(targetEntity);
	var cmpTargetPlayerStatisticsTracker = QueryOwnerInterface(targetEntity, IID_StatisticsTracker);
	if (cmpTargetPlayerStatisticsTracker) cmpTargetPlayerStatisticsTracker.LostEntity(targetEntity);

	// if unit can collect loot, lets try to collect it
	var cmpLooter = Engine.QueryInterface(killerEntity, IID_Looter);
	if (cmpLooter)
	{
		cmpLooter.Collect(targetEntity);
	}
};

Attack.prototype.InterpolatedLocation = function(ent, lateness)
{
	var targetPositionCmp = Engine.QueryInterface(ent, IID_Position);
	if (!targetPositionCmp) // TODO: handle dead target properly
		return undefined;
	var curPos = targetPositionCmp.GetPosition();
	var prevPos = targetPositionCmp.GetPreviousPosition();
	lateness /= 1000;
	return {"x": (curPos.x * (this.turnLength - lateness) + prevPos.x * lateness) / this.turnLength,
	        "z": (curPos.z * (this.turnLength - lateness) + prevPos.z * lateness) / this.turnLength};
};

Attack.prototype.VectorDistance = function(p1, p2)
{
	return Math.sqrt((p1.x - p2.x)*(p1.x - p2.x) + (p1.z - p2.z)*(p1.z - p2.z));
};

Attack.prototype.VectorDot = function(p1, p2)
{
	return (p1.x * p2.x + p1.z * p2.z);
};

Attack.prototype.VectorCross = function(p1, p2)
{
	return (p1.x * p2.z - p1.z * p2.x);
};

Attack.prototype.VectorLength = function(p)
{
	return Math.sqrt(p.x*p.x + p.z*p.z);
};

// Tests whether it point is inside of ent's footprint
Attack.prototype.testCollision = function(ent, point, lateness)
{
	var targetPosition = this.InterpolatedLocation(ent, lateness);
	var targetShape = Engine.QueryInterface(ent, IID_Footprint).GetShape();
	
	if (!targetShape || !targetPosition)
		return false;
	
	if (targetShape.type === 'circle')
	{
		return (this.VectorDistance(point, targetPosition) < targetShape.radius);
	}
	else
	{
		var targetRotation = Engine.QueryInterface(ent, IID_Position).GetRotation().y;
		
		var dx = point.x - targetPosition.x;
		var dz = point.z - targetPosition.z;
		
		var dxr = Math.cos(targetRotation) * dx - Math.sin(targetRotation) * dz;
		var dzr = Math.sin(targetRotation) * dx + Math.cos(targetRotation) * dz;
		
		return (-targetShape.width/2 <= dxr && dxr < targetShape.width/2 && -targetShape.depth/2 <= dzr && dzr < targetShape.depth/2);
	}
};

Attack.prototype.MissileHit = function(data, lateness)
{
	
	var targetPosition = this.InterpolatedLocation(data.target, lateness);
	if (!targetPosition)
		return;
	
	if (this.template.Ranged.Splash) // splash damage, do this first in case the direct hit kills the target
	{
		var friendlyFire = this.template.Ranged.Splash.FriendlyFire;
		var splashRadius = this.template.Ranged.Splash.Range;
		var splashShape = this.template.Ranged.Splash.Shape;
		
		var ents = this.GetNearbyEntities(data.target, this.VectorDistance(data.position, targetPosition) * 2 + splashRadius, friendlyFire);
		ents.push(data.target); // Add the original unit to the list of splash damage targets
		
		for (var i = 0; i < ents.length; i++)
		{
			var entityPosition = this.InterpolatedLocation(ents[i], lateness);
			var radius = this.VectorDistance(data.position, entityPosition);
			
			if (radius < splashRadius)
			{
				var multiplier = 1;
				if (splashShape == "Circular") // quadratic falloff
				{
					multiplier *= 1 - ((radius * radius) / (splashRadius * splashRadius));
				}
				else if (splashShape == "Linear")
				{
					// position of entity relative to where the missile hit
					var relPos = {"x": entityPosition.x - data.position.x, "z": entityPosition.z - data.position.z};
					
					var splashWidth = splashRadius / 5;
					var parallelDist = this.VectorDot(relPos, data.direction);
					var perpDist = Math.abs(this.VectorCross(relPos, data.direction));
					
					// Check that the unit is within the distance splashWidth of the line starting at the missile's 
					// landing point which extends in the direction of the missile for length splashRadius.
					if (parallelDist > -splashWidth && perpDist < splashWidth)
					{
						// Use a quadratic falloff in both directions
						multiplier = (splashRadius*splashRadius - parallelDist*parallelDist) / (splashRadius*splashRadius)
						             * (splashWidth*splashWidth - perpDist*perpDist) / (splashWidth*splashWidth);
					}
					else
					{
						multiplier = 0;
					}
				}
				var newData = {"type": data.type + ".Splash", "target": ents[i], "damageMultiplier": multiplier};
				this.CauseDamage(newData);
			}
		}
	}
	
	if (this.testCollision(data.target, data.position, lateness))
	{
		// Hit the primary target
		this.CauseDamage(data);
		
		// Remove the projectile
		var cmpProjectileManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_ProjectileManager);
		cmpProjectileManager.RemoveProjectile(data.projectileId);
	}
	else
	{
		// If we didn't hit the main target look for nearby units
		var ents = this.GetNearbyEntities(data.target, this.VectorDistance(data.position, targetPosition) * 2);
		
		for (var i = 0; i < ents.length; i++)
		{
			if (this.testCollision(ents[i], data.position, lateness))
			{
				var newData = {"type": data.type, "target": ents[i]};
				this.CauseDamage(newData);
				
				// Remove the projectile
				var cmpProjectileManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_ProjectileManager);
				cmpProjectileManager.RemoveProjectile(data.projectileId);
			}
		}
	}
};

Attack.prototype.GetNearbyEntities = function(startEnt, range, friendlyFire)
{
	var cmpPlayerManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_PlayerManager);
	var cmpOwnership = Engine.QueryInterface(this.entity, IID_Ownership);
	var owner = cmpOwnership.GetOwner();
	var cmpPlayer = Engine.QueryInterface(cmpPlayerManager.GetPlayerByID(owner), IID_Player);
	var numPlayers = cmpPlayerManager.GetNumPlayers();
	var players = [];
	
	for (var i = 1; i < numPlayers; ++i)
	{	
		// Only target enemies unless friendly fire is on
		if (cmpPlayer.IsEnemy(i) || friendlyFire)
			players.push(i);
	}
	
	var rangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
	return rangeManager.ExecuteQuery(startEnt, 0, range, players, IID_DamageReceiver);
}

/**
 * Inflict damage on the target
 */
Attack.prototype.CauseDamage = function(data)
{
	var strengths = this.GetAttackStrengths(data.type);
	
	var damageMultiplier = this.GetAttackBonus(data.type, data.target);
	if (data.damageMultiplier !== undefined)
		damageMultiplier *= data.damageMultiplier;
	
	var cmpDamageReceiver = Engine.QueryInterface(data.target, IID_DamageReceiver);
	if (!cmpDamageReceiver)
		return;
	var targetState = cmpDamageReceiver.TakeDamage(strengths.hack * damageMultiplier, strengths.pierce * damageMultiplier, strengths.crush * damageMultiplier);
	// if target killed pick up loot and credit experience
	if (targetState.killed == true)
	{
		this.TargetKilled(this.entity, data.target);
	}

	Engine.PostMessage(data.target, MT_Attacked,
		{ "attacker": this.entity, "target": data.target, "type": data.type });

	PlaySound("attack_impact", this.entity);
};

Attack.prototype.OnUpdate = function(msg)
{
	this.turnLength = msg.turnLength;
}

Engine.RegisterComponentType(IID_Attack, "Attack", Attack);