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* Keyframe interpolation for smooth skeletal animations
*
* Provides interpolation between animation keyframes for smooth 60fps playback.
* Supports linear, ease-in, ease-out, and ease-in-out easing functions.
*
* @module systems/animation/KeyframeInterpolation
* @category Animation System
* @korean 키프레임보간
*/
import * as THREE from "three";
import type {
AnimationKeyframe,
SkeletalAnimation,
SkeletalRig,
} from "../../types/skeletal";
/**
* Easing function type
*
* @param t - Time value between 0 and 1
* @returns Eased value between 0 and 1
*
* @korean 이징함수타입
*/
type EasingFunction = (t: number) => number;
/**
* Cubic bezier control points for easing curves
*
* **Korean**: 3차 베지어 제어점
*
* @public
* @category Animation
* @korean 베지어제어점
*/
export interface BezierControlPoints {
/** First control point x (0-1) */
readonly p1x: number;
/** First control point y (0-1) */
readonly p1y: number;
/** Second control point x (0-1) */
readonly p2x: number;
/** Second control point y (0-1) */
readonly p2y: number;
/**
* Enable precision mode for exact bezier curve calculation
*
* **Reserved for future implementation.**
*
* When false (default), uses simplified approximation assuming x progresses linearly with t.
* This is standard for CSS cubic-bezier() and provides good results with minimal overhead.
*
* When true (future), will perform iterative solving for accurate x-t mapping (higher CPU cost).
* This would enable non-linear time progression for more complex easing curves.
*
* Currently unused - kept in interface for forward compatibility without breaking API changes.
*
* @korean 정밀모드
*/
readonly precisionMode?: boolean;
}
/**
* Cubic bezier easing for natural movement
*
* **Korean**: 3차 베지어 이징
*
* Implements cubic bezier curve interpolation for smooth, natural motion.
* Based on CSS cubic-bezier() function specification.
*
* This function uses a configuration object approach for better API clarity.
* By default, uses simplified approximation (x progresses linearly with t) which
* provides good results for animation with minimal overhead. Enable precisionMode
* for exact calculations when needed.
*
* @param t - Input time (0-1)
* @param options - Bezier control points and configuration
* @returns Eased value
*
* @example
* ```typescript
* // Natural Korean martial arts movement (physics-based)
* const eased = cubicBezierWithOptions(0.5, {
* p1x: 0.25, p1y: 0.1, p2x: 0.25, p2y: 1.0
* });
*
* // With precision mode for exact calculation
* const precise = cubicBezierWithOptions(0.5, {
* p1x: 0.42, p1y: 0, p2x: 0.58, p2y: 1.0,
* precisionMode: true
* });
* ```
*
* @korean 3차베지어이징옵션
*/
export function cubicBezierWithOptions(
t: number,
options: BezierControlPoints
): number {
// Clamp t to [0, 1]
const clampedT = Math.max(0, Math.min(1, t));
// For performance, use direct calculation (standard for CSS cubic-bezier)
// Note: options.precisionMode is currently unused and reserved for future implementation
// where we could add iterative solving for exact x-t mapping
const u = 1 - clampedT;
// Cubic bezier formula: B(t) = (1-t)³P₀ + 3(1-t)²tP₁ + 3(1-t)t²P₂ + t³P₃
// For easing, P₀ = (0,0) and P₃ = (1,1), so:
// y(t) = 3(1-t)²t*p1y + 3(1-t)t²*p2y + t³
const result = 3 * u * u * clampedT * options.p1y +
3 * u * clampedT * clampedT * options.p2y +
clampedT * clampedT * clampedT;
return result;
}
/**
* Cubic bezier easing (legacy function signature for backward compatibility)
*
* **Korean**: 3차 베지어 이징 (레거시)
*
* @param t - Input time (0-1)
* @param p1x - First control point x (0-1) - currently unused, reserved for precision mode
* @param p1y - First control point y (can exceed 0-1 for overshoot)
* @param p2x - Second control point x (0-1) - currently unused, reserved for precision mode
* @param p2y - Second control point y (can exceed 0-1 for overshoot)
* @returns Eased value
*
* @deprecated Use cubicBezierWithOptions for clearer API
* @korean 3차베지어이징레거시
*/
export function cubicBezier(
t: number,
p1x: number,
p1y: number,
p2x: number,
p2y: number
): number {
return cubicBezierWithOptions(t, { p1x, p1y, p2x, p2y });
}
/**
* Create a cubic bezier easing function with control points
*
* **Korean**: 베지어 이징 함수 생성
*
* Factory function to create reusable bezier easing functions.
*
* @param points - Bezier control points
* @returns Easing function
*
* @korean 베지어이징함수생성
*/
export function createBezierEasing(points: BezierControlPoints): EasingFunction {
return (t: number) => cubicBezier(t, points.p1x, points.p1y, points.p2x, points.p2y);
}
/**
* Preset bezier easing curves for Korean martial arts movements
*
* **Korean**: 무도 동작 이징 곡선
*
* @public
* @category Animation
* @korean 무도동작이징곡선
*/
export const BEZIER_PRESETS = {
/**
* Natural motion with physics-based acceleration/deceleration
* Ideal for: Stance transitions, body rotations, weight shifts
* **Korean**: 자연스러운 물리 기반 동작
*/
naturalMotion: { p1x: 0.25, p1y: 0.1, p2x: 0.25, p2y: 1.0 },
/**
* Smooth S-curve for fluid transitions
* Ideal for: Attack wind-ups, defensive positioning, footwork
* **Korean**: 부드러운 S곡선 전환
*/
smoothTransition: { p1x: 0.42, p1y: 0.0, p2x: 0.58, p2y: 1.0 },
/**
* Quick start with gentle landing
* Ideal for: Strike recoil, guard recovery, step completion
* **Korean**: 빠른 시작과 부드러운 착지
*/
quickStart: { p1x: 0.1, p1y: 0.8, p2x: 0.25, p2y: 1.0 },
/**
* Explosive power curve
* Ideal for: Explosive strikes, power techniques, ki projection
* **Korean**: 폭발적 힘 곡선
*/
explosivePower: { p1x: 0.05, p1y: 0.9, p2x: 0.2, p2y: 1.0 },
/**
* Controlled deceleration
* Ideal for: Defensive withdrawals, cautious movements, guard stance
* **Korean**: 제어된 감속
*/
controlledSlow: { p1x: 0.6, p1y: 0.0, p2x: 0.9, p2y: 0.4 },
} as const;
/**
* Linear easing (no easing)
*
* @param t - Input time (0-1)
* @returns Same as input
*
* @korean 선형이징
*/
export const easeLinear: EasingFunction = (t: number): number => t;
/**
* Ease-in (slow start, fast end) - Simple quadratic
*
* @param t - Input time (0-1)
* @returns Eased value
*
* @korean 이즈인
*/
export const easeIn: EasingFunction = (t: number): number => t * t;
/**
* Ease-out (fast start, slow end) - Simple quadratic
*
* @param t - Input time (0-1)
* @returns Eased value
*
* @korean 이즈아웃
*/
export const easeOut: EasingFunction = (t: number): number => t * (2 - t);
/**
* Ease-in-out (slow start, slow end) - Simple quadratic
*
* @param t - Input time (0-1)
* @returns Eased value
*
* @korean 이즈인아웃
*/
export const easeInOut: EasingFunction = (t: number): number => {
Iif (t < 0.5) {
return 2 * t * t;
}
return -1 + (4 - 2 * t) * t;
};
/**
* Natural motion bezier easing (preset)
*
* **Korean**: 자연스러운 동작 이징
*
* Physics-based movement ideal for Korean martial arts.
*
* @param t - Input time (0-1)
* @returns Eased value
*
* @korean 자연동작이징
*/
export const easeNaturalMotion: EasingFunction = createBezierEasing(BEZIER_PRESETS.naturalMotion);
/**
* Smooth transition bezier easing (preset)
*
* **Korean**: 부드러운 전환 이징
*
* S-curve for fluid stance transitions.
*
* @param t - Input time (0-1)
* @returns Eased value
*
* @korean 부드러운전환이징
*/
export const easeSmoothTransition: EasingFunction = createBezierEasing(BEZIER_PRESETS.smoothTransition);
/**
* Explosive power bezier easing (preset)
*
* **Korean**: 폭발적 힘 이징
*
* Explosive acceleration for power strikes.
*
* @param t - Input time (0-1)
* @returns Eased value
*
* @korean 폭발적힘이징
*/
export const easeExplosivePower: EasingFunction = createBezierEasing(BEZIER_PRESETS.explosivePower);
/**
* Extended easing function names including bezier presets
*
* **Korean**: 확장된 이징 함수 이름
*
* @public
* @category Animation
* @korean 확장이징함수이름
*/
export type EasingName =
| "linear"
| "ease-in"
| "ease-out"
| "ease-in-out"
| "natural-motion"
| "smooth-transition"
| "quick-start"
| "explosive-power"
| "controlled-slow";
/**
* Get easing function by name
*
* **Korean**: 이름으로 이징 함수 구하기
*
* @param name - Easing function name (supports bezier presets)
* @returns Easing function
*
* @example
* ```typescript
* // Get natural motion easing for Korean martial arts
* const easing = getEasingFunction("natural-motion");
* const easedValue = easing(0.5); // Smooth physics-based interpolation
*
* // Get explosive power for strike animations
* const powerEasing = getEasingFunction("explosive-power");
* ```
*
* @korean 이징함수구하기
*/
export const getEasingFunction = (
name: EasingName = "linear"
): EasingFunction => {
switch (name) {
case "ease-in":
return easeIn;
case "ease-out":
return easeOut;
case "ease-in-out":
return easeInOut;
case "natural-motion":
return easeNaturalMotion;
case "smooth-transition":
return easeSmoothTransition;
case "quick-start":
return createBezierEasing(BEZIER_PRESETS.quickStart);
case "explosive-power":
return easeExplosivePower;
case "controlled-slow":
return createBezierEasing(BEZIER_PRESETS.controlledSlow);
default:
return easeLinear;
}
};
/**
* Find keyframes surrounding current time
*
* Returns the two keyframes to interpolate between for current animation time.
*
* @param animation - Skeletal animation
* @param currentTime - Current time in animation (seconds)
* @returns Tuple of [previousKeyframe, nextKeyframe, interpolationFactor]
*
* @korean 주변키프레임찾기
*/
export const findSurroundingKeyframes = (
animation: SkeletalAnimation,
currentTime: number
): [AnimationKeyframe, AnimationKeyframe, number] => {
const { keyframes } = animation;
// Clamp time to animation duration
const clampedTime = Math.max(
0,
Math.min(currentTime, animation.duration)
);
// Find keyframes
let prevKeyframe = keyframes[0];
let nextKeyframe = keyframes[keyframes.length - 1];
let interpolationFactor = 0;
for (let i = 0; i < keyframes.length - 1; i++) {
const current = keyframes[i];
const next = keyframes[i + 1];
if (clampedTime >= current.time && clampedTime <= next.time) {
prevKeyframe = current;
nextKeyframe = next;
// Calculate interpolation factor (0 to 1)
const timeDelta = next.time - current.time;
Eif (timeDelta > 0) {
interpolationFactor = (clampedTime - current.time) / timeDelta;
}
break;
}
}
return [prevKeyframe, nextKeyframe, interpolationFactor];
};
/**
* Interpolate between two Euler rotations
*
* Performs spherical linear interpolation (slerp) for smooth rotation.
*
* @param from - Start rotation
* @param to - End rotation
* @param t - Interpolation factor (0-1)
* @param easingFn - Easing function to apply
* @returns Interpolated rotation
*
* @korean 회전보간
*/
export const interpolateRotation = (
from: THREE.Euler,
to: THREE.Euler,
t: number,
easingFn: EasingFunction = easeLinear
): THREE.Euler => {
const easedT = easingFn(t);
// Convert Euler to Quaternion for proper slerp
const fromQuat = new THREE.Quaternion().setFromEuler(from);
const toQuat = new THREE.Quaternion().setFromEuler(to);
// Slerp between quaternions
const result = new THREE.Quaternion().slerpQuaternions(
fromQuat,
toQuat,
easedT
);
// Convert back to Euler
const resultEuler = new THREE.Euler().setFromQuaternion(result);
return resultEuler;
};
/**
* Interpolate between two Vector3 positions
*
* Performs linear interpolation for smooth position changes.
*
* @param from - Start position
* @param to - End position
* @param t - Interpolation factor (0-1)
* @param easingFn - Easing function to apply
* @returns Interpolated position
*
* @korean 위치보간
*/
export const interpolatePosition = (
from: THREE.Vector3,
to: THREE.Vector3,
t: number,
easingFn: EasingFunction = easeLinear
): THREE.Vector3 => {
const easedT = easingFn(t);
return new THREE.Vector3().lerpVectors(from, to, easedT);
};
/**
* Get interpolated keyframe at current time
*
* Calculates bone transformations by interpolating between keyframes.
*
* @param animation - Skeletal animation
* @param currentTime - Current time in animation (seconds)
* @returns Interpolated keyframe
*
* @korean 보간된키프레임구하기
*/
export const getInterpolatedKeyframe = (
animation: SkeletalAnimation,
currentTime: number
): AnimationKeyframe => {
const [prevKeyframe, nextKeyframe, t] =
findSurroundingKeyframes(animation, currentTime);
// Get easing function from next keyframe
const easingFn = getEasingFunction(nextKeyframe.easing);
// Interpolate bone rotations
const boneRotations = new Map<string, THREE.Euler>();
const allBoneNames = new Set([
...prevKeyframe.boneRotations.keys(),
...nextKeyframe.boneRotations.keys(),
]);
for (const boneName of allBoneNames) {
const prevRotation =
prevKeyframe.boneRotations.get(boneName) ?? new THREE.Euler();
const nextRotation =
nextKeyframe.boneRotations.get(boneName) ?? new THREE.Euler();
const interpolated = interpolateRotation(
prevRotation,
nextRotation,
t,
easingFn
);
boneRotations.set(boneName, interpolated);
}
// Interpolate bone positions
const bonePositions = new Map<string, THREE.Vector3>();
const allPositionBones = new Set([
...prevKeyframe.bonePositions.keys(),
...nextKeyframe.bonePositions.keys(),
]);
for (const boneName of allPositionBones) {
const prevPosition =
prevKeyframe.bonePositions.get(boneName) ?? new THREE.Vector3();
const nextPosition =
nextKeyframe.bonePositions.get(boneName) ?? new THREE.Vector3();
const interpolated = interpolatePosition(
prevPosition,
nextPosition,
t,
easingFn
);
bonePositions.set(boneName, interpolated);
}
return {
time: currentTime,
boneRotations,
bonePositions,
easing: nextKeyframe.easing,
};
};
/**
* Apply keyframe to skeletal rig
*
* Updates all bone transformations based on keyframe data.
*
* @param rig - Skeletal rig to update
* @param keyframe - Keyframe to apply
*
* @korean 키프레임적용
*/
export const applyKeyframeToRig = (
rig: SkeletalRig,
keyframe: AnimationKeyframe
): void => {
// Apply bone rotations
keyframe.boneRotations.forEach((rotation, boneName) => {
const bone = rig.bones.get(boneName);
Eif (bone) {
bone.rotation.copy(rotation);
}
});
// Apply bone positions (offset from rest pose)
keyframe.bonePositions.forEach((position, boneName) => {
const bone = rig.bones.get(boneName);
Eif (bone) {
// Add position offset to rest position
bone.position.copy(bone.restPosition).add(position);
}
});
};
/**
* Blend between two keyframes
*
* Creates smooth transition between two animations for animation blending.
* Useful for transitioning between stance change and attack, etc.
*
* @param keyframe1 - First keyframe
* @param keyframe2 - Second keyframe
* @param blendFactor - Blend amount (0 = keyframe1, 1 = keyframe2)
* @returns Blended keyframe
*
* @korean 키프레임블렌드
*/
export const blendKeyframes = (
keyframe1: AnimationKeyframe,
keyframe2: AnimationKeyframe,
blendFactor: number
): AnimationKeyframe => {
const clampedBlend = Math.max(0, Math.min(1, blendFactor));
// Blend rotations
const boneRotations = new Map<string, THREE.Euler>();
const allBones = new Set([
...keyframe1.boneRotations.keys(),
...keyframe2.boneRotations.keys(),
]);
allBones.forEach((boneName) => {
const rot1 = keyframe1.boneRotations.get(boneName) ?? new THREE.Euler();
const rot2 = keyframe2.boneRotations.get(boneName) ?? new THREE.Euler();
const blended = interpolateRotation(rot1, rot2, clampedBlend);
boneRotations.set(boneName, blended);
});
// Blend positions
const bonePositions = new Map<string, THREE.Vector3>();
const allPositionBones = new Set([
...keyframe1.bonePositions.keys(),
...keyframe2.bonePositions.keys(),
]);
allPositionBones.forEach((boneName) => {
const pos1 = keyframe1.bonePositions.get(boneName) ?? new THREE.Vector3();
const pos2 = keyframe2.bonePositions.get(boneName) ?? new THREE.Vector3();
const blended = interpolatePosition(pos1, pos2, clampedBlend);
bonePositions.set(boneName, blended);
});
return {
time: 0,
boneRotations,
bonePositions,
easing: "linear",
};
};
/**
* Update animation state
*
* Advances animation time and returns current interpolated keyframe.
* Handles looping animations automatically.
*
* @param animation - Skeletal animation
* @param currentTime - Current time in animation
* @param deltaTime - Time since last update (seconds)
* @param playbackSpeed - Speed multiplier (1.0 = normal)
* @returns Updated time and current keyframe
*
* @korean 애니메이션상태업데이트
*/
export const updateAnimation = (
animation: SkeletalAnimation,
currentTime: number,
deltaTime: number,
playbackSpeed = 1.0
): { time: number; keyframe: AnimationKeyframe; completed: boolean } => {
// Advance time
let newTime = currentTime + deltaTime * playbackSpeed;
let completed = false;
// Handle looping or completion
if (newTime >= animation.duration) {
Iif (animation.loop) {
newTime = newTime % animation.duration;
} else {
newTime = animation.duration;
completed = true;
}
}
// Get interpolated keyframe
const keyframe = getInterpolatedKeyframe(animation, newTime);
return {
time: newTime,
keyframe,
completed,
};
};
/**
* Cross-fade blend between two animations
*
* **Korean**: 크로스페이드 블렌드
*
* Smoothly blends between two overlapping animations to prevent popping.
* Uses cubic bezier easing for natural transitions.
*
* @param animation1 - First animation
* @param time1 - Current time in first animation
* @param animation2 - Second animation
* @param time2 - Current time in second animation
* @param blendFactor - Blend weight (0 = animation1, 1 = animation2)
* @param easingName - Easing curve for blend transition
* @returns Blended keyframe
*
* @example
* ```typescript
* // Cross-fade from idle to attack over 100ms
* const blended = crossFadeAnimations(
* idleAnim, idleTime,
* attackAnim, attackTime,
* 0.5, // 50% blend
* "smooth-transition"
* );
* applyKeyframeToRig(rig, blended);
* ```
*
* @korean 크로스페이드블렌드
*/
export const crossFadeAnimations = (
animation1: SkeletalAnimation,
time1: number,
animation2: SkeletalAnimation,
time2: number,
blendFactor: number,
easingName: EasingName = "smooth-transition"
): AnimationKeyframe => {
const keyframe1 = getInterpolatedKeyframe(animation1, time1);
const keyframe2 = getInterpolatedKeyframe(animation2, time2);
// Apply easing to blend factor
const easingFn = getEasingFunction(easingName);
const easedBlend = easingFn(Math.max(0, Math.min(1, blendFactor)));
return blendKeyframes(keyframe1, keyframe2, easedBlend);
};
/**
* Motion prediction state for latency reduction
*
* **Korean**: 동작 예측 상태
*
* Stores recent animation velocities for motion prediction.
*
* @public
* @category Animation
* @korean 동작예측상태
*/
export interface MotionPredictionState {
/** Recent position velocities per bone */
readonly velocities: Map<string, THREE.Vector3>;
/** Recent rotation velocities per bone */
readonly angularVelocities: Map<string, THREE.Euler>;
/** Last update timestamp */
readonly lastUpdateTime: number;
}
/**
* Create motion prediction state
*
* **Korean**: 동작 예측 상태 생성
*
* @returns Initial motion prediction state
* @korean 동작예측상태생성
*/
export const createMotionPredictionState = (): MotionPredictionState => ({
velocities: new Map(),
angularVelocities: new Map(),
lastUpdateTime: 0,
});
/**
* Update motion prediction state with new keyframe
*
* **Korean**: 동작 예측 상태 업데이트
*
* Calculates velocities from keyframe differences for motion prediction.
*
* @param state - Current prediction state
* @param previousKeyframe - Previous animation keyframe
* @param currentKeyframe - Current animation keyframe
* @param deltaTime - Time elapsed between keyframes
* @returns Updated prediction state
*
* @korean 동작예측상태업데이트
*/
export const updateMotionPrediction = (
state: MotionPredictionState,
previousKeyframe: AnimationKeyframe,
currentKeyframe: AnimationKeyframe,
deltaTime: number
): MotionPredictionState => {
if (deltaTime <= 0) return state;
const newVelocities = new Map<string, THREE.Vector3>();
const newAngularVelocities = new Map<string, THREE.Euler>();
// Calculate position velocities
currentKeyframe.bonePositions.forEach((currentPos, boneName) => {
const prevPos = previousKeyframe.bonePositions.get(boneName);
Eif (prevPos) {
const velocity = new THREE.Vector3()
.subVectors(currentPos, prevPos)
.divideScalar(deltaTime);
newVelocities.set(boneName, velocity);
}
});
// Calculate angular velocities using quaternion-based rotation differences
// This avoids gimbal lock and angle wrapping issues with Euler angle differences
currentKeyframe.boneRotations.forEach((currentRot, boneName) => {
const prevRot = previousKeyframe.boneRotations.get(boneName);
Eif (prevRot) {
// Convert Euler rotations to quaternions
const qCurrent = new THREE.Quaternion().setFromEuler(currentRot);
const qPrev = new THREE.Quaternion().setFromEuler(prevRot);
// Calculate relative rotation: qDiff = qCurrent * qPrev^(-1)
const qDiff = qCurrent.clone().multiply(qPrev.clone().invert());
// Extract axis-angle representation for angular velocity
const axis = new THREE.Vector3();
const wClamped = THREE.MathUtils.clamp(qDiff.w, -1, 1);
let angle = 2 * Math.acos(wClamped);
const sinHalfAngle = Math.sqrt(1 - wClamped * wClamped);
if (sinHalfAngle < 0.0001) {
// If sinHalfAngle is too small, rotation is negligible - use zero velocity
axis.set(0, 0, 0);
angle = 0;
} else {
// Extract normalized axis from quaternion
axis.set(
qDiff.x / sinHalfAngle,
qDiff.y / sinHalfAngle,
qDiff.z / sinHalfAngle
);
}
// Use shortest rotation path
Iif (angle > Math.PI) {
angle -= 2 * Math.PI;
}
// Angular velocity vector = axis * (angle / deltaTime)
const angularVelocityVec = axis.multiplyScalar(angle / deltaTime);
// Store as Euler for consistency with existing API
const angularVel = new THREE.Euler(
angularVelocityVec.x,
angularVelocityVec.y,
angularVelocityVec.z,
currentRot.order
);
newAngularVelocities.set(boneName, angularVel);
}
});
return {
velocities: newVelocities,
angularVelocities: newAngularVelocities,
lastUpdateTime: performance.now(),
};
};
/**
* Predict future keyframe using motion prediction
*
* **Korean**: 동작 예측으로 미래 키프레임 예측
*
* Reduces perceived latency by predicting future bone positions/rotations
* based on current velocities. Typical prediction: 16-33ms (1-2 frames at 60fps).
*
* @param currentKeyframe - Current animation keyframe
* @param predictionState - Motion prediction state
* @param predictionTime - Time ahead to predict (seconds, typically 0.016-0.033)
* @returns Predicted keyframe
*
* @example
* ```typescript
* // Predict 1 frame ahead (16.67ms at 60fps) for <50ms total latency
* const predicted = predictFutureKeyframe(
* currentKeyframe,
* motionState,
* 0.01667
* );
* applyKeyframeToRig(rig, predicted);
* ```
*
* @korean 미래키프레임예측
*/
export const predictFutureKeyframe = (
currentKeyframe: AnimationKeyframe,
predictionState: MotionPredictionState,
predictionTime: number
): AnimationKeyframe => {
// Clamp prediction time to reasonable bounds (max 50ms)
const clampedPrediction = Math.min(predictionTime, 0.05);
// Predict bone positions
const predictedPositions = new Map<string, THREE.Vector3>();
currentKeyframe.bonePositions.forEach((currentPos, boneName) => {
const velocity = predictionState.velocities.get(boneName);
if (velocity) {
// Apply damping to prevent overshoot (0.8 factor for natural motion)
const predicted = currentPos.clone().add(
velocity.clone().multiplyScalar(clampedPrediction * 0.8)
);
predictedPositions.set(boneName, predicted);
} else {
predictedPositions.set(boneName, currentPos.clone());
}
});
// Predict bone rotations
const predictedRotations = new Map<string, THREE.Euler>();
currentKeyframe.boneRotations.forEach((currentRot, boneName) => {
const angularVel = predictionState.angularVelocities.get(boneName);
if (angularVel) {
// Apply damping to prevent overshoot
const predicted = new THREE.Euler(
currentRot.x + angularVel.x * clampedPrediction * 0.8,
currentRot.y + angularVel.y * clampedPrediction * 0.8,
currentRot.z + angularVel.z * clampedPrediction * 0.8,
currentRot.order
);
predictedRotations.set(boneName, predicted);
} else E{
predictedRotations.set(boneName, currentRot.clone());
}
});
return {
time: currentKeyframe.time + clampedPrediction,
boneRotations: predictedRotations,
bonePositions: predictedPositions,
easing: currentKeyframe.easing,
};
};
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