drive-between-the-lines/src/main.ts

import { generateWorld } from './sim/world';
import { applyWear, deriveHandling, freshCondition, repair } from './sim/car';
import { createHeat, stepHeat } from './sim/heat';
import { routeAt, segmentAt } from './sim/roads';
import { baseAt, placeBases } from './sim/bases';
import { buildGraph } from './sim/routing';
import { createIntel, observe, survey } from './sim/intel';
import { accept, createQuests, offersAt, stepQuest, type Offer } from './sim/quests';
import { createHeatProps } from './heatProps';
import { seedFromString } from './core/rng';
import { startLoop } from './core/loop';
import { createInput } from './core/input';
import { createPhysics } from './physics/physics';
import { createDriveState, drive } from './physics/drive';
import { createScene, updateCamera } from './render/scene';
import { createMarkers } from './render/markers';
import { createHud } from './ui/hud';
import { createBoard } from './ui/board';
import { CAR, WHEELS } from './carSpec';

function resolveSeed(): number {
  const raw = new URLSearchParams(location.search).get('seed');
  if (!raw) return 1337;
  const n = Number(raw);
  return Number.isFinite(n) ? n >>> 0 : seedFromString(raw);
}

async function boot() {
  const seed = resolveSeed();
  const model = generateWorld(seed);
  const bases = placeBases(model.roads, model.spawn);
  const graph = buildGraph(model.roads);

  const physics = await createPhysics(model);
  const view = createScene(model);
  const markers = createMarkers(view.scene, bases);
  const input = createInput();
  const hud = createHud(seed);
  const board = createBoard();
  const driveState = createDriveState();
  const heat = createHeat(model.roads);
  const heatProps = createHeatProps(model.roads, physics, view.scene);
  const intel = createIntel(model.roads);
  const quests = createQuests();

  let condition = freshCondition();
  let elapsed = 0;
  let respawnLatch = false;
  /** The road being travelled along — includes the verge, not just the tarmac. */
  let currentSegment: number | null = null;
  let onTarmac = false;
  /** Offers are generated once per arrival at a base, not every frame. */
  let openBase: number | null = null;
  let offers: Offer[] = [];
  let notice = '';
  let noticeUntil = 0;

  const say = (text: string, seconds = 4) => {
    notice = text;
    noticeUntil = elapsed + seconds;
  };

  const nodeOf = (id: number) => model.roads.nodes[id]!;

  document.getElementById('boot')?.remove();

  startLoop({
    fixedUpdate(dt) {
      elapsed += dt;
      const cmd = input.read();

      if (cmd.respawn && !respawnLatch) physics.respawn();
      respawnLatch = cmd.respawn;

      drive(physics, driveState, cmd, deriveHandling(condition), dt);
      physics.step(dt);

      // Wear is applied from what actually happened this step, not from intent.
      const speed = physics.vehicle.currentVehicleSpeed();
      const distance = Math.abs(speed) * dt;
      condition = applyWear(condition, {
        dt,
        distance,
        throttle: Math.abs(cmd.throttle),
        impactForce: physics.drainImpactForce(),
      });

      // Heat: the road remembers being used — including being driven alongside.
      const at = physics.chassis.translation();
      currentSegment = routeAt(model.roads, at.x, at.z)?.id ?? null;
      onTarmac = segmentAt(model.roads, at.x, at.z) !== null;
      heatProps.sync(
        stepHeat(heat, { dt, segmentId: currentSegment, distance }),
        heat,
        currentSegment,
      );
      // Driving a road is how you learn what is on it.
      if (currentSegment !== null) observe(intel, heat, currentSegment, elapsed);

      const base = baseAt(bases, at.x, at.z);
      const stopped = Math.abs(speed) < 2.5;

      // --- Quest board: only when parked at a base with nothing in hand ---
      if (base && stopped && !quests.active) {
        if (openBase !== base.nodeId) {
          openBase = base.nodeId;
          // Seeded by base and runs completed, not by time: leaving and coming
          // straight back must not reroll a board you did not like.
          offers = offersAt(
            quests,
            model.roads,
            graph,
            intel,
            base,
            elapsed,
            seed ^ (base.nodeId * 31) ^ (quests.completed * 7919),
          );
          board.show(base, offers);
        }
        const chosen = cmd.select === null ? undefined : offers[cmd.select - 1];
        if (chosen) {
          accept(quests, chosen, base);
          board.hide();
          openBase = null;
          say(`${chosen.type === 'recon' ? 'Survey' : 'Supply run'} accepted.`);
        }
      } else if (openBase !== null) {
        openBase = null;
        board.hide();
      }

      // --- Active mission ---
      const quest = quests.active;
      if (quest) {
        const target = nodeOf(quest.targetNode);
        const event = stepQuest(quests, {
          dt,
          distanceToTarget: Math.hypot(target.x - at.x, target.z - at.z),
          atBase: base,
          speed: Math.abs(speed),
        });

        if (event?.kind === 'arrived') {
          intel.visitedNodes.add(quest.targetNode);
          say('At the target. Stop the car and hold position.');
        } else if (event?.kind === 'worked') {
          if (event.type === 'recon') {
            const count = survey(intel, heat, model.roads, target.x, target.z, elapsed);
            say(`Survey complete — ${count} roads mapped. Report back to any base.`);
          } else {
            say('Cargo delivered. Report back to any base.');
          }
        } else if (event?.kind === 'completed') {
          const outcome = repair(condition, quests.parts);
          const spent = quests.parts - outcome.unused;
          condition = outcome.condition;
          quests.parts = outcome.unused;
          say(
            spent > 0.001
              ? `Handed in. Repairs used ${spent.toFixed(2)} parts.`
              : 'Handed in. Nothing left worth repairing.',
          );
        }
      }

      markers.setObjective(quests.active ? nodeOf(quests.active.targetNode) : null);
    },

    render(_alpha, frameDt) {
      // No transform interpolation yet: at a 60 Hz fixed step it is not yet
      // worth the bookkeeping. Revisit if the step rate ever drops.
      const p = physics.chassis.translation();
      const r = physics.chassis.rotation();
      view.car.position.set(p.x, p.y, p.z);
      view.car.quaternion.set(r.x, r.y, r.z, r.w);

      for (let i = 0; i < WHEELS.length; i++) {
        const pivot = view.wheels[i]!;
        const suspension =
          physics.vehicle.wheelSuspensionLength(i) ?? CAR.wheel.suspensionRestLength;
        pivot.position.y = CAR.wheel.offsetY - suspension;
        pivot.rotation.y = physics.vehicle.wheelSteering(i) ?? 0;
        pivot.children[0]!.rotation.x = physics.vehicle.wheelRotation(i) ?? 0;
      }

      // Static blocks never move; only the crates need syncing.
      for (let i = 0; i < view.obstacles.length; i++) {
        if (model.obstacles[i]!.kind !== 'crate') continue;
        const body = physics.obstacleBodies[i]!;
        const t = body.translation();
        const q = body.rotation();
        const mesh = view.obstacles[i]!;
        mesh.position.set(t.x, t.y, t.z);
        mesh.quaternion.set(q.x, q.y, q.z, q.w);
      }

      view.followSun();
      markers.update(elapsed);
      updateCamera(view, frameDt, physics.vehicle.currentVehicleSpeed());
      view.renderer.render(view.scene, view.camera);

      const quest = quests.active;
      const target = quest ? nodeOf(quest.targetNode) : null;
      hud.update(physics.vehicle.currentVehicleSpeed(), condition, elapsed, {
        heat: {
          segmentId: currentSegment,
          onTarmac,
          value: currentSegment === null ? 0 : heat.value[currentSegment]!,
          level: currentSegment === null ? null : heat.level[currentSegment]!,
        },
        quest: quest
          ? {
              type: quest.type,
              stage: quest.stage,
              novel: quest.novel,
              worked: quest.worked,
              distance: target
                ? Math.hypot(target.x - p.x, target.z - p.z)
                : 0,
            }
          : null,
        completed: quests.completed,
        parts: quests.parts,
        notice: elapsed < noticeUntil ? notice : '',
      });
    },
  });
}

boot().catch((err) => {
  console.error(err);
  const boot = document.getElementById('boot');
  if (boot) boot.textContent = `failed to start: ${err}`;
});