tanqiu/assets/scripts/BulletControl/effects/BulletTrajectory.ts

import { _decorator, Component, Node, Vec3, math } from 'cc';
import { BulletTrajectoryConfig } from '../BulletTypes';
const { ccclass } = _decorator;

/**
 * 弹道控制（可移植版，去除重力，采用渐近转向）
 * - straight：匀速直线
 * - arc：弧线（方向按目标或期望方向渐近旋转）
 * - guided：强导航（延迟后按目标方向渐近旋转）
 * 说明：不做命中判定/自动选敌，仅负责轨迹运动。
 */
@ccclass('BCBulletTrajectory')
export class BulletTrajectory extends Component {
  private cfg: BulletTrajectoryConfig | null = null;
  private velocity: Vec3 = new Vec3(0, 0, 0);
  private target: Node | null = null;
  private homingTimer = 0;

  // 渐近转向用方向缓存
  private arcDir: Vec3 | null = null;
  private arcTargetDir: Vec3 | null = null;
  private guidedDir: Vec3 | null = null;
  private guidedTargetDir: Vec3 | null = null;

  // 外观对齐/自旋选项
  private facingShouldRotate: boolean | null = null; // shouldRotate === false 时贴合速度
  private facingOffsetDeg: number = 0;              // 图片朝向修正（度）
  private facingChildName: string | null = 'Pellet';// 优先旋转的子节点名
  private autoSpinSpeedDeg: number = 720;           // 自旋速度（度/秒）

  public init(cfg: BulletTrajectoryConfig, direction: Vec3, startPos: Vec3, originNode?: Node | null) {
    this.cfg = { ...cfg };
    const speed = Math.max(0, this.cfg.speed ?? 0);
    const baseDir = direction?.clone() ?? new Vec3(1, 0, 0);
    if (baseDir.length() === 0) baseDir.set(1, 0, 0);
    baseDir.normalize();

    // 初始速度（straight）
    this.velocity.set(baseDir.x * speed, baseDir.y * speed, 0);
    this.node.setPosition(startPos);
    this.homingTimer = 0;

    // 为 arc/guided 建立初始偏移与目标方向（便于产生弧线）
    const sign = Math.random() < 0.5 ? 1 : -1;
    const radArc = (45 * Math.PI / 180) * sign; // 初始偏转角
    const c = Math.cos(radArc);
    const s = Math.sin(radArc);
    const offsetDir = new Vec3(
      baseDir.x * c - baseDir.y * s,
      baseDir.x * s + baseDir.y * c,
      0
    ).normalize();

    this.arcDir = offsetDir.clone();
    this.arcTargetDir = baseDir.clone();

    const radGuided = (35 * Math.PI / 180) * sign;
    const cg = Math.cos(radGuided);
    const sg = Math.sin(radGuided);
    const guidedOffset = new Vec3(
      baseDir.x * cg - baseDir.y * sg,
      baseDir.x * sg + baseDir.y * cg,
      0
    ).normalize();
    this.guidedDir = guidedOffset.clone();
    this.guidedTargetDir = baseDir.clone();
  }

  public setTarget(node: Node | null) {
    this.target = node;
  }

  /**
   * 配置外观对齐/自旋
   */
  public setFacingOptions(opts: { shouldRotate?: boolean; offsetDeg?: number; targetChildName?: string; spinSpeedDeg?: number }) {
    this.facingShouldRotate = (opts && 'shouldRotate' in opts) ? (opts.shouldRotate ?? null) : this.facingShouldRotate;
    if (opts && typeof opts.offsetDeg === 'number') this.facingOffsetDeg = opts.offsetDeg;
    if (opts && typeof opts.targetChildName === 'string') this.facingChildName = opts.targetChildName || null;
    if (opts && typeof opts.spinSpeedDeg === 'number') this.autoSpinSpeedDeg = opts.spinSpeedDeg;
  }

  public getCurrentVelocity(): Vec3 {
    return this.velocity.clone();
  }

  update(dt: number) {
    if (!this.cfg) return;
    const type = this.cfg.type;
    if (type === 'straight') {
      this.moveLinear(dt);
    } else if (type === 'arc') {
      this.updateArc(dt);
    } else if (type === 'guided') {
      this.updateGuided(dt);
    } else {
      this.moveLinear(dt);
    }

    // 更新外观对齐/自旋
    this.updateFacing(dt);
  }

  private moveLinear(dt: number) {
    const dx = this.velocity.x * dt;
    const dy = this.velocity.y * dt;
    const p = this.node.position;
    this.node.setPosition(p.x + dx, p.y + dy);
  }

  /**
   * 弧线：按目标或期望方向渐近旋转，保持速率恒定
   */
  private updateArc(dt: number) {
    if (!this.arcDir || !this.arcTargetDir || !this.cfg) {
      this.moveLinear(dt);
      return;
    }

    // 若有目标则按目标方向渐近；否则保持初始目标方向
    if (this.target && this.target.isValid) {
      const pos = this.node.worldPosition;
      const tpos = this.target.worldPosition;
      const toTarget = new Vec3(tpos.x - pos.x, tpos.y - pos.y, 0).normalize();
      this.arcTargetDir.set(toTarget);
    }

    const rotateSpeed = Math.max(0, Math.min(1, this.cfg.rotateSpeed ?? 0.2));
    const t = Math.min(1, rotateSpeed * dt);
    const newDir = new Vec3();
    Vec3.slerp(newDir, this.arcDir, this.arcTargetDir, t);
    this.arcDir.set(newDir);

    const speed = Math.max(0, this.cfg.speed ?? 0);
    this.velocity.set(newDir.x * speed, newDir.y * speed, 0);
    this.moveLinear(dt);
  }

  /**
   * Guided：延迟后按目标方向渐近旋转，保持速率恒定
   */
  private updateGuided(dt: number) {
    if (!this.guidedDir || !this.guidedTargetDir || !this.cfg) {
      this.moveLinear(dt);
      return;
    }

    const delay = Math.max(0, this.cfg.homingDelay ?? 0);
    this.homingTimer += dt;
    if (this.homingTimer < delay) {
      // 延迟期：沿初始引导方向匀速飞行
      const speed = Math.max(0, this.cfg.speed ?? 0);
      this.velocity.set(this.guidedDir.x * speed, this.guidedDir.y * speed, 0);
      this.moveLinear(dt);
      return;
    }

    // 计算期望方向（若无目标则维持原方向）
    if (this.target && this.target.isValid) {
      const pos = this.node.worldPosition;
      const tpos = this.target.worldPosition;
      const toTarget = new Vec3(tpos.x - pos.x, tpos.y - pos.y, 0).normalize();
      this.guidedTargetDir.set(toTarget);
    }

    const rotateSpeed = Math.max(0, Math.min(1, this.cfg.rotateSpeed ?? 0.25));
    const strength = Math.max(0, Math.min(1, this.cfg.homingStrength ?? 0.15));
    const t = Math.min(1, rotateSpeed * (0.8 + strength * 0.4) * dt);
    const newDir = new Vec3();
    Vec3.slerp(newDir, this.guidedDir, this.guidedTargetDir, t);
    this.guidedDir.set(newDir);

    const speed = Math.max(0, this.cfg.speed ?? 0);
    this.velocity.set(newDir.x * speed, newDir.y * speed, 0);
    this.moveLinear(dt);
  }

  /**
   * 根据当前速度更新外观角度（shouldRotate === false 贴合；否则自旋）
   */
  private updateFacing(dt: number) {
    // 未配置则不处理，保持移植版轻耦合
    if (this.facingShouldRotate === null) return;

    const vel = this.getCurrentVelocity();
    if (!vel || (Math.abs(vel.x) < 1e-4 && Math.abs(vel.y) < 1e-4)) return;

    // 目标节点：优先子节点
    let targetNode: Node | null = null;
    if (this.facingChildName) {
      const child = this.node.getChildByName(this.facingChildName);
      if (child) targetNode = child;
    }
    if (!targetNode) targetNode = this.node;

    if (this.facingShouldRotate === false) {
      const deg = math.toDegree(Math.atan2(vel.y, vel.x)) + this.facingOffsetDeg;
      targetNode.angle = deg;
    } else {
      // 自旋：不强制贴合轨迹切线
      targetNode.angle += this.autoSpinSpeedDeg * dt;
    }
  }
}