@rpgjs/physic/dist/index37.js

A deterministic 2D top-down physics library for RPG, sandbox and MMO games

import { AABB } from "./index4.js";
import { Vector2 } from "./index2.js";
class LinearRepulsion {
  /**
   * @param engine - Physics engine used for spatial queries
   * @param targetProvider - Function returning the target position
   * @param maxSpeed - Maximum speed in units per second
   * @param repulseRadius - Radius used to sample nearby obstacles
   * @param repulseWeight - Weight of the repulsion force
   * @param ignoredEntity - Optional entity to exclude from avoidance (e.g. the target)
   */
  constructor(engine, targetProvider, maxSpeed = 2.5, repulseRadius = 2, repulseWeight = 4, ignoredEntity) {
    this.engine = engine;
    this.targetProvider = targetProvider;
    this.maxSpeed = maxSpeed;
    this.repulseRadius = repulseRadius;
    this.repulseWeight = repulseWeight;
    this.ignoredEntity = ignoredEntity;
    this.repulseRadiusSq = repulseRadius * repulseRadius;
  }
  update(body, _dt) {
    const entity = body.getEntity?.();
    if (!entity) {
      throw new Error("LinearRepulsion requires a movement body backed by a physics entity.");
    }
    const targetPosition = this.targetProvider();
    const toTarget = new Vector2(targetPosition.x - entity.position.x, targetPosition.y - entity.position.y);
    const distance = toTarget.length();
    if (distance > 0) {
      toTarget.divInPlace(distance);
    } else {
      toTarget.set(0, 0);
    }
    const bounds = AABB.fromCenterSize(entity.position.x, entity.position.y, this.repulseRadius * 2, this.repulseRadius * 2);
    const neighbors = this.engine.queryAABB(bounds);
    const ignored = this.ignoredEntity?.();
    const push = new Vector2(0, 0);
    for (const other of neighbors) {
      if (other === entity || other === ignored || other.isStatic()) {
        continue;
      }
      const diff = new Vector2(entity.position.x - other.position.x, entity.position.y - other.position.y);
      const d2 = diff.lengthSquared();
      if (d2 > this.repulseRadiusSq || d2 === 0) {
        continue;
      }
      const d = Math.sqrt(d2);
      const weight = this.repulseWeight * (this.repulseRadius - Math.min(d, this.repulseRadius)) / this.repulseRadius;
      push.addInPlace(diff.mul(weight / d));
    }
    const maxPush = this.maxSpeed * 3;
    const pushLength = push.length();
    if (pushLength > maxPush && pushLength > 0) {
      push.mulInPlace(maxPush / pushLength);
    }
    const desired = toTarget.mul(this.maxSpeed).add(push);
    const desiredLength = desired.length();
    if (desiredLength > this.maxSpeed && desiredLength > 0) {
      desired.mulInPlace(this.maxSpeed / desiredLength);
    }
    if (!Number.isFinite(desired.x) || !Number.isFinite(desired.y)) {
      entity.setVelocity({ x: 0, y: 0 });
      return;
    }
    body.setVelocity(desired);
  }
  setParameters(maxSpeed, repulseRadius, repulseWeight) {
    if (maxSpeed !== void 0) {
      this.maxSpeed = maxSpeed;
    }
    if (repulseRadius !== void 0) {
      this.repulseRadius = repulseRadius;
      this.repulseRadiusSq = repulseRadius * repulseRadius;
    }
    if (repulseWeight !== void 0) {
      this.repulseWeight = repulseWeight;
    }
  }
}
export {
  LinearRepulsion
};
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