AutoRunnerDriver

AutoRunnerDriver

The drivers of every car the player isn't driving.

What it does

AutoRunnerDriver works in road space, "how far along" and "how far across", because that is how a driver thinks: stay in lane two, pull alongside, get behind the player and push. Each role decides where across the road it wants to be and how fast it wants to go, then writes throttle, brake and steer onto its car's CarDrive.

Use it in a scene

{
  "Gunner": {
    "tags": ["car", "enemy", "gunner"],
    "components": {
      "MeshPrimitive": {
        "primitive": "box",
        "width": 1.9,
        "height": 1.3,
        "depth": 4.4
      },
      "CarDrive": { "keyboardControlled": false, "maxSpeed": 60 },
      "AutoRunnerDriver": {
        "role": "gunner",
        "cruiseSpeed": 40,
        "sideGap": 5.4,
        "shellPool": "shell",
        "pellets": 3
      }
    }
  }
}

The player's car carries the player tag, which is what attackers look for. A Gunner also needs a shell pool of AutoRunnerProjectile rounds. With no HighwayRoad in the scene, the road is taken to be straight along +Z with three lanes.

Steering by pure pursuit

Every role steers the same way. Pick a point some way up the road at the offset you want, and turn toward it:

  // Pure pursuit: a point up the road at the offset we want.
  const look = 10 + Math.abs(i.speed) * 0.45;
  const pt = road.toWorld(i.s + look, aimU);
  const desired = Math.atan2(pt.x - i.x, pt.z - i.z);
  let steer = steerFor(i.heading, desired, p.steerGain);

civilian at 26 m/s, moving over one lane (3.7 m) on a straight road
look ahead = 10 + 26 × 0.45     = 21.7 m
aim angle  = atan(3.7 ÷ 21.7)   ≈ 0.17 rad
steer      = 0.17 × 1.7         ≈ 0.29 of full lock

A faster car looks further up the road, so the same lane change asks for less wheel and it drifts over instead of jerking.

Attack runs

An attacker closes in fast from behind and matches pace once level. Once level, every attackEvery seconds (give or take 30%), it makes a run lasting attackLength. A rammer swerves in, a shover leans the player toward the nearer edge, and a gunner fires one volley of pellets shells. It gives up once the player is more than giveUpBehind metres ahead, or 45 m behind.

Police

A police car keeps its lane at cruiseSpeed. It starts a chase when the player goes faster than speedLimit within sight metres, ahead or behind, or when the player rams it or shoots it. In a chase it drives like a shover, flashes its roof lights (headlights.beacon.set) and sends autoRunnerDriver.pursuit with on: true.

The chase ends after calmSeconds in a row of the player keeping to the limit, or being out of sight. Out of sight means hidden (a car in the weapons truck is a ghost, and drivers cannot see ghosts) or more than giveUpBehind metres ahead. While the player keeps to the limit, the police car only follows, 12 m back.

{
  "PoliceBlueprint": {
    "tags": ["car", "police"],
    "components": {
      "AutoRunnerDriver": {
        "role": "police",
        "cruiseSpeed": 28,
        "speedLimit": 36,
        "sight": 45,
        "calmSeconds": 3
      },
      "Headlights": { "beacon": true, "beaconHeight": 1.45 }
    }
  }
}

Losing control

Smoke (autoRunnerDriver.blind) makes a driver wander, slow down and hold fire. In a spin-out it lets go of the throttle, brakes lightly and steers half as hard. A car tagged wreck coasts to a stop, and brakes only while it is still rolling, because CarDrive turns a brake held at a standstill into reverse.

Settings

Events

Needs

• CarDrive is the car each driver steers. The driver writes its throttle, brake and steer.
• CarCollision tells the driver when its car is spinning, and how long each car is for following gaps. Its hit event is how police notice a ram.
• MeshPrimitive gives every car's position.
• HighwayRoad supplies the lanes, width and curve of the road.
• AutoRunnerProjectile fires a Gunner's shells, and its hit event is how police notice a shot.