HighwaySpawner

HighwaySpawner

Decides when a car comes out of a pool onto the road, and when it goes back.

What it does

• Civilians are a budget: about civilianDensity per 100 m of road ahead, never more than maxCivilians. Each one goes into a free lane, faces up the road and is sent off at its own pace.
• Police patrol in the traffic. One turns up ahead every policeEvery seconds or so, from level policeFrom. There are never more than maxPolice at once.
• Enemies come from behind, the way a car grows out of the bottom of the screen. Which kind comes is a weighted pick from the enemies allowed at that level.
• A car that dies becomes a wreck: its driver lets go, and after wreckSeconds it is cleared.
• Cars that fall releaseBehind metres behind or run releaseAhead metres ahead go back to their pools.

A car straight out of a pool is standing still. A parked car 150 m ahead is a roadblock, not traffic, so each new car gets a carDrive.nudge that sets it moving. Civilians leave at a speed between civilianSpeedMin and civilianSpeedMax. Enemies leave enemyCatchUp m/s faster than the player, so they close from behind.

Use it in a scene

{
  "Traffic": {
    "components": {
      "HighwaySpawner": {
        "follow": "Player",
        "civilians": ["civilian"],
        "police": ["police"],
        "policeEvery": 22,
        "maxPolice": 2,
        "enemies": [
          { "pool": "rammer", "from": 1, "weight": 3 },
          { "pool": "gunner", "from": 2, "weight": 2 },
          { "pool": "shover", "from": 3, "weight": 1.5 }
        ]
      }
    }
  }
}

Every name in civilians, police and enemies is a Pool. The scene also needs a HighwayRoad; with no road, nothing spawns. Only the first HighwaySpawner in a scene runs.

The civilian budget

Traffic is a count to hold:

export function civilianTarget(windowLength: number, density: number, max: number): number {
  return Math.min(max, Math.round((windowLength / 100) * density));
}

The System passes aheadMax as the window:

defaults:         240 m × 1.2 per 100 m = 2.88 → 3 civilians
Endless Rampage:  240 m × 2.1 per 100 m = 5.04 → 5 civilians

When a car is released, the count drops below the target and a new one is placed. Until half the target is out, several can arrive in the same frame; after that, new civilians come 0.35 s apart.

A new car only goes where no car sits within minGap metres along the road in the same lane. An enemy needs only 0.7 of that.

The difficulty curve

    enemyInterval: Math.max(2.5, baseInterval * Math.pow(0.86, l - 1)),
    maxEnemies: Math.min(6, baseMax + Math.floor((l - 1) / 1.5)),
    traffic: Math.min(1.6, 1 + (l - 1) * 0.08),

Each level cuts the gap between enemies by 14%, adds an enemy slot about every one and a half levels, and adds 8% more civilians. With the defaults:

level 1:  an enemy every 10.0 s, 1 on the road at once
level 3:  an enemy every  7.4 s, 2 at once
level 5:  an enemy every  5.5 s, 3 at once
level 11: an enemy every  2.5 s (the floor)

Each wait is jittered by ±25%, so the arrivals never feel like a metronome. A director raises the level with highwaySpawner.level.set.

Settings

Events

Needs

• Pool holds every car it places.
• HighwayRoad gives lanes, bridges (it never spawns on one) and road distance.
• CarDrive marks which entities are cars, gives the player's speed, and takes the nudge.
• CarCollision lets it skip ghost cars in the gap check.
• MeshPrimitive gives each car's position and sets a new car's facing.
• AutoRunnerDriver gives each new car its lane and lets go of a wreck.