BakeBoneRotation.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Playables;
#if UNITY_EDITOR
using UnityEditor;
#endif

// Original: https://styly.cc/ja/tips/aigaalince001_jojomon_particlelive1/ CreateBoneAnimeClip.cs
public class BakeBoneRotations : MonoBehaviour
{
    [SerializeField] private PlayableDirector director;
    [SerializeField] private Transform rootPath;
    [SerializeField] private List<Transform> rootBones;

#if UNITY_EDITOR
    List<AnimCurve> curves;

    class AnimCurve {
        public string relativePath;
        public Type type;
        public string property;
        public Func<float> value;
        public AnimationCurve curve;
        public int count;
        public bool first;
        public bool skipped;
        public float lastTime1;
        public float lastTime0;
        public float lastValue1;
        public float lastValue0;
        public float timeCand;
        public float valueCand;
        public float prevTime;
        public float prevValue;
        public bool smooth;
        public bool degree;
        public AnimCurve(string relativePath, Type type, string property, Func<float> value, bool smooth = true, bool degree = false) {
            this.relativePath = relativePath;
            this.type = type;
            this.property = property; 
            this.value = value;
            this.smooth = smooth;
            this.degree = degree;
            curve = new AnimationCurve();
            count = 0;
            first = true;
            skipped = false;
            lastTime1 = 0;
            lastTime0 = 0;
            lastValue1 = 0;
            lastValue0 = 0;
            timeCand = 0;
            valueCand = 0;
            prevTime = 0;
            prevValue = 0;
        }

        private void AddKey(float t, float v) {
            if(smooth) {
                if(t == prevTime) {
                    curve.AddKey(t, v);
                } else {
                    float g = (v - prevValue) / (t - prevTime);
                    Keyframe f = new Keyframe(t, v);
                    f.weightedMode = WeightedMode.Both;
                    f.inTangent = f.outTangent = g;
                    curve.AddKey(f);
                }
            } else {
                Keyframe f = new Keyframe(t, v);
                f.weightedMode = WeightedMode.Both;
                f.inWeight = f.outWeight = 0; // discrete
                // f.inWeight = f.outWeight = 1; // linear
                curve.AddKey(f);
            }
            count++;
            lastTime1 = lastTime0;
            lastTime0 = t;
            lastValue1 = lastValue0;
            lastValue0 = v;
        }

        private float PickValue(float p, float c) {
            if(degree) {
                c -= p;
                c = (((c + 180) % 360 + 360) % 360) - 180;
                c += p;
            }
            return c;
        }

        private float calcT;
        private float calcV;

        public bool Tick(float t) {
            if(first) {
                first = false;
                return false; 
            }
            float v = PickValue(lastValue0, value());
            bool accept = false;
            if(count < 2) {
                accept = true;
            } else {
                float le = (t - lastTime1) / (lastTime0 - lastTime1);
                float pr = lastValue1 + (lastValue0 - lastValue1) * le;
                float diff = Mathf.Abs(pr - v);
                if(diff > 1.0f) {
                    accept = true;
                }
            }
            calcT = t;
            calcV = v;
            return accept;
        }

        public void Proc(bool accept) {
            float t = calcT;
            float v = calcV;
            if(accept) {
                AddKey(t, v);
                skipped = false;
            } else {
                timeCand = t;
                valueCand = v;
                skipped = true;
            }
            prevTime = t;
            prevValue = v;
        }

        public void Done() {
            if(skipped) {
                AddKey(timeCand, valueCand);
            }
        }
    }

    bool recording = true;

    private void Start() {
        curves = new List<AnimCurve>();
        foreach(Transform rootBone in rootBones) {
            Transform[] children = rootBone.GetComponentsInChildren<Transform>();
            foreach(Transform t in children) {
                string path = AnimationUtility.CalculateTransformPath(t, rootPath);
                curves.Add(new AnimCurve(path, typeof(Transform), "localEulerAnglesRaw.x", ()=>t.localEulerAngles.x, true, true));
                curves.Add(new AnimCurve(path, typeof(Transform), "localEulerAnglesRaw.y", ()=>t.localEulerAngles.y, true, true));
                curves.Add(new AnimCurve(path, typeof(Transform), "localEulerAnglesRaw.z", ()=>t.localEulerAngles.z, true, true));
            }
        }
    }

    private void Update() {
        if(recording) {
            float t = (float) director.time;
            for(int i=0;i<curves.Count;i+=3) {
                AnimCurve c0 = curves[i+0];
                AnimCurve c1 = curves[i+1];
                AnimCurve c2 = curves[i+2];
                bool a = false;
                a = c0.Tick(t) || a;
                a = c1.Tick(t) || a;
                a = c2.Tick(t) || a;
                c0.Proc(a);
                c1.Proc(a);
                c2.Proc(a);
            }
            foreach(AnimCurve curve in curves) {
                curve.Tick((float) director.time);
            }
        }
        if(Input.GetKeyDown(KeyCode.Space)) {
            recording = false;
            AnimationClip clip = new AnimationClip();
            foreach(AnimCurve c in curves) {
                c.Done();
                AnimationCurve cu = c.curve;
                clip.SetCurve(c.relativePath, c.type, c.property, c.curve);
            }
            string path = AssetDatabase.GenerateUniqueAssetPath($"Assets/{rootPath.name}_clip.anim");
            AssetDatabase.CreateAsset(clip, path);
            AssetDatabase.SaveAssets();
            AssetDatabase.Refresh();
        }
    }

#endif
}