110 lines
3.3 KiB
TypeScript
110 lines
3.3 KiB
TypeScript
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/**
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* @zh 插值器接口
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* @en Interpolator Interface
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*
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* @zh 提供状态插值的抽象
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* @en Provides abstraction for state interpolation
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*/
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// =============================================================================
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// 插值器接口 | Interpolator Interface
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// =============================================================================
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/**
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* @zh 插值器接口
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* @en Interpolator interface
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*/
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export interface IInterpolator<T> {
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/**
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* @zh 在两个状态之间插值
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* @en Interpolate between two states
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*
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* @param from - @zh 起始状态 @en Start state
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* @param to - @zh 目标状态 @en Target state
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* @param t - @zh 插值因子 (0-1) @en Interpolation factor (0-1)
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* @returns @zh 插值后的状态 @en Interpolated state
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*/
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interpolate(from: T, to: T, t: number): T;
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}
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/**
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* @zh 外推器接口
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* @en Extrapolator interface
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*/
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export interface IExtrapolator<T> {
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/**
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* @zh 基于当前状态外推
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* @en Extrapolate based on current state
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*
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* @param state - @zh 当前状态 @en Current state
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* @param deltaTime - @zh 外推时间（秒）@en Extrapolation time in seconds
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* @returns @zh 外推后的状态 @en Extrapolated state
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*/
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extrapolate(state: T, deltaTime: number): T;
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}
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// =============================================================================
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// 内置插值器 | Built-in Interpolators
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// =============================================================================
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/**
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* @zh 线性插值函数
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* @en Linear interpolation function
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*/
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export function lerp(a: number, b: number, t: number): number {
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return a + (b - a) * t;
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}
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/**
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* @zh 角度插值函数（处理环绕）
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* @en Angle interpolation function (handles wrap-around)
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*/
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export function lerpAngle(a: number, b: number, t: number): number {
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let diff = b - a;
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while (diff > Math.PI) diff -= Math.PI * 2;
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while (diff < -Math.PI) diff += Math.PI * 2;
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return a + diff * t;
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}
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/**
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* @zh 平滑阻尼插值
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* @en Smooth damp interpolation
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*
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* @param current - @zh 当前值 @en Current value
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* @param target - @zh 目标值 @en Target value
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* @param velocity - @zh 当前速度（将被修改）@en Current velocity (will be modified)
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* @param smoothTime - @zh 平滑时间 @en Smooth time
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* @param deltaTime - @zh 帧时间 @en Delta time
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* @param maxSpeed - @zh 最大速度 @en Maximum speed
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* @returns @zh [新值, 新速度] @en [new value, new velocity]
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*/
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export function smoothDamp(
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current: number,
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target: number,
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velocity: number,
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smoothTime: number,
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deltaTime: number,
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maxSpeed: number = Infinity
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): [number, number] {
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smoothTime = Math.max(0.0001, smoothTime);
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const omega = 2 / smoothTime;
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const x = omega * deltaTime;
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const exp = 1 / (1 + x + 0.48 * x * x + 0.235 * x * x * x);
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let change = current - target;
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const maxChange = maxSpeed * smoothTime;
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change = Math.max(-maxChange, Math.min(maxChange, change));
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const temp = (velocity + omega * change) * deltaTime;
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let newVelocity = (velocity - omega * temp) * exp;
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let newValue = target + (change + temp) * exp;
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// Prevent overshoot
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if ((target - current > 0) === (newValue > target)) {
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newValue = target;
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newVelocity = (newValue - target) / deltaTime;
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}
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return [newValue, newVelocity];
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}
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