Mobs

How can I make a mob of enemies that shoot projectiles at their nearest player?

To make mobs of enemies, Spawn an entity to represent each enemy, and give it a behavior that finds the nearest player and shoots every tick.

Step 1: Spawn some mobs

In this example, our mobs of enemies are called Aliens. We will define what an Alien does in the next step.

    repeat 20 {
        Spawn unit {
            Alien
        }
    }

Step 2: Make mobs attack

To make our Alien attack, we have simply given them a behavior that runs every few ticks and finds the nearest player to shoot at.

pub fn unit.Alien() {
    // ...

    on Tick(2.5s * Random) {
        let enemy = QueryNearest(filter=Category:Hero)
        if !enemy { continue }
        Spawn projectile {
            Bullet(heading=Angle(enemy.Pos - Pos), parent=unit)
        }
    }
}

• QueryNearest finds the nearest player.
• The on Tick(2.5s * Random) means it will rerun this block somewhere between every 0s and 2.5s, chosen randomly

Full Code Listing

pub tangible category Category:Hero
pub tangible category Category:Alien
pub tangible category Category:Projectile

pub game fn World.Main() {
    TopContent { "Arrow keys to move, click to fire" }

    SpawnEachPlayer owner {
        Spawn unit {
            Hero
        }
    }

    repeat 20 {
        Spawn unit {
            Alien
        }
    }
}

pub fn unit.Hero([owner]) {
    use body=this, radius=1, shape=Circle
    Body(pos=20*RandomVector)
    PolygonSprite(ownerColor=true)
    PolygonCollider(category=Category:Hero)
    DecaySpeed(1)
    DecayTurnRate(1)

    on BeforePhysics {
        Move(0.25 * Joystick)
    }

    // Shoot towards pointer on click
    on ButtonDown(Click) {
        Spawn projectile {
            Bullet(heading=Angle(Pointer - Pos), parent=unit)
        }
    }
}

pub fn unit.Alien() {
    use body=this, radius=1, shape=Equilateral(numPoints=4)
    Body(pos=20*RandomVector)
    PolygonSprite(color=#0f0)
    PolygonCollider(category=Category:Alien)
    DecaySpeed(1)
    DecayTurnRate(1)

    // Shoot towards nearest hero every so often
    on Tick(2.5s * Random) {
        let enemy = QueryNearest(filter=Category:Hero)
        if !enemy { continue }
        Spawn projectile {
            Bullet(heading=Angle(enemy.Pos - Pos), parent=unit)
        }
    }

    // Take 50 steps in a random direction every so often
    on Tick(0.5s * Random) {
        let step = 0.25 * RandomVector
        repeat 50 {
            Move(step)
            await Tick
        }
    }
}

// Bullet flies towards a target with a speed of 30
pub fn projectile.Bullet(heading, parent) {
    use body=this, radius=0.25, shape=Circle
    Body(pos=parent.Pos, velocity=30*heading.Direction)
    PolygonSprite(color=#fc0)
    PolygonCollider(category=Category:Projectile, parent=)

    on BeforeCollide that { Expire }
    once Tick(1.5s) { Expire }
}

Open in Editor