feat(win): T-WIN-007 特征提取 + 流式 DTW 评分引擎

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class_name DtwMatcher
extends RefCounted
## DTW 评分引擎 —— T-WIN-007
##
## 参考序列来自 Web 服务端预处理产出的关键点序列(契约 contracts/model-formats.md §2.1),
## 查询序列来自 Android 端实时推流。两侧结构同构,均为 PoseFeatures.FeatureVector。
##
## 采用 Sakoe-Chiba 带状约束:|i - j| <= band。对舞蹈跟练场景,
## 玩家与参考基本同步开始,该约束既降低复杂度又避免病态对齐。
const PoseFeatures = preload("res://src/score/pose_features.gd")
## 默认带宽(帧)。30 FPS 下 15 帧 ≈ 0.5 秒的抖动容忍。
const DEFAULT_BAND := 15
## 整段 DTW(离线/测试用)
## 返回 { distance, normalized, path, steps };distance 为路径累计代价。
static func compute_full(query: Array, reference: Array, band: int = DEFAULT_BAND) -> Dictionary:
var n := query.size()
var m := reference.size()
var result := {
"distance": INF,
"normalized": INF,
"path": [],
"steps": 0,
}
if n == 0 or m == 0:
return result
# 代价矩阵(完整存储,便于回溯);用 INF 表示不可达
var cost: Array = []
cost.resize(n)
for i in n:
var row := PackedFloat32Array()
row.resize(m)
row.fill(INF)
cost[i] = row
for i in n:
var j_lo: int = maxi(0, i - band)
var j_hi: int = mini(m - 1, i + band)
for j in range(j_lo, j_hi + 1):
var step := PoseFeatures.weighted_distance(query[i], reference[j])
if i == 0 and j == 0:
cost[i][j] = step
continue
var best := INF
if i > 0 and j_lo <= j and j <= mini(m - 1, i - 1 + band):
best = minf(best, cost[i - 1][j])
if j > 0:
best = minf(best, cost[i][j - 1])
if i > 0 and j > 0:
best = minf(best, cost[i - 1][j - 1])
cost[i][j] = step + (best if best < INF else 0.0)
# 端点可取最后一行的带内最小值(允许参考尾部未被走完)
var end_j := -1
var end_cost := INF
for j in range(maxi(0, n - 1 - band), mini(m - 1, n - 1 + band) + 1):
if cost[n - 1][j] < end_cost:
end_cost = cost[n - 1][j]
end_j = j
if end_j < 0:
return result
# 回溯
var path: Array = []
var i := n - 1
var j := end_j
var guard := 0
while i >= 0 and j >= 0 and guard < n + m + 8:
guard += 1
path.append(Vector2i(i, j))
if i == 0 and j == 0:
break
# cost 是无类型 Array,元素为 Variant;显式声明为 float 以做运行期转换
var diag := INF
var up := INF
var left := INF
if i > 0 and j > 0:
diag = cost[i - 1][j - 1]
if i > 0:
up = cost[i - 1][j]
if j > 0:
left = cost[i][j - 1]
if diag <= up and diag <= left:
i -= 1
j -= 1
elif up <= left:
i -= 1
else:
j -= 1
path.reverse()
result["distance"] = end_cost
result["steps"] = path.size()
result["normalized"] = end_cost / float(maxi(path.size(), 1))
result["path"] = path
return result
## 流式 DTW:逐帧推送查询向量,随时可读取当前评分
class StreamingDtw extends RefCounted:
var _reference: Array = []
var _band: int = DtwMatcher.DEFAULT_BAND
var _m: int = 0
## 上一行代价(仅带内),_prev_lo 为其对应的参考起始下标
var _prev_costs := PackedFloat32Array()
var _prev_lo: int = 0
var _cur_costs := PackedFloat32Array()
var _cur_lo: int = 0
var _row: int = -1
var _last_normalized: float = INF
var _last_cost: float = INF
var _last_j: int = -1
var _finished: bool = false
func _init(reference: Array, band: int = DtwMatcher.DEFAULT_BAND) -> void:
_reference = reference
_band = maxi(band, 0)
_m = reference.size()
func reference_length() -> int:
return _m
func frames_consumed() -> int:
return _row + 1
## 参考序列是否已被走完
func is_finished() -> bool:
return _finished
## 推进一帧;返回本次的 { cost, normalized, j, finished }
func push(query: PoseFeatures.FeatureVector) -> Dictionary:
if _m == 0:
_finished = true
return {"cost": INF, "normalized": INF, "j": -1, "finished": true}
_row += 1
var i := _row
var lo: int = maxi(0, i - _band)
var hi: int = mini(_m - 1, i + _band)
var width := hi - lo + 1
_cur_lo = lo
_cur_costs = PackedFloat32Array()
_cur_costs.resize(width)
_cur_costs.fill(INF)
var row_best := INF
var row_best_j := -1
for j in range(lo, hi + 1):
var step := PoseFeatures.weighted_distance(query, _reference[j])
var value := 0.0
if i == 0 and j == 0:
value = step
else:
var best := INF
# 左邻(本行)
if j > lo:
best = minf(best, _cur_costs[j - 1 - lo])
# 上邻(上一行同列)
var up := _prev_at(j)
if up < INF:
best = minf(best, up)
# 左上对角
var diag := _prev_at(j - 1)
if diag < INF:
best = minf(best, diag)
value = step + (best if best < INF else 0.0)
_cur_costs[j - lo] = value
if value < row_best:
row_best = value
row_best_j = j
_prev_costs = _cur_costs
_prev_lo = lo
_last_cost = row_best
_last_j = row_best_j
# 归一化:路径至少经过 max(i, j)+1 个格点
var steps: int = maxi(i, row_best_j) + 1
_last_normalized = row_best / float(maxi(steps, 1))
if row_best_j >= _m - 1:
_finished = true
return {
"cost": _last_cost,
"normalized": _last_normalized,
"j": _last_j,
"finished": _finished,
}
func _prev_at(j: int) -> float:
if _prev_costs.is_empty():
return INF
var idx := j - _prev_lo
if idx < 0 or idx >= _prev_costs.size():
return INF
return _prev_costs[idx]
## 当前平均每步代价(越小越贴合)
func normalized_cost() -> float:
return _last_normalized
## 对齐到的参考帧下标
func reference_cursor() -> int:
return _last_j
## 进度 [0,1]
func progress() -> float:
if _m <= 0:
return 0.0
return clampf(float(_last_j + 1) / float(_m), 0.0, 1.0)
func reset() -> void:
_prev_costs = PackedFloat32Array()
_cur_costs = PackedFloat32Array()
_prev_lo = 0
_cur_lo = 0
_row = -1
_last_normalized = INF
_last_cost = INF
_last_j = -1
_finished = false
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class_name PoseFeatures
extends RefCounted
## 关键点 → DTW 特征向量 —— 契约 contracts/skeleton-topology.md §5(冻结)
##
## 每帧特征 = [33 × (x, y, z), 9 个关节角余弦] = 108 维。
## 低置信度点(conf < 0.5)对应的维度权重置 0,不参与代价计算。
##
## 关节角三元组顺序冻结为:
## [shoulder_L, shoulder_R, elbow_L, elbow_R, hip_L, hip_R, knee_L, knee_R, spine]
const KeypointFrame = preload("res://src/net/keypoint_frame.gd")
const KEYPOINT_COUNT := 33
const VIRTUAL_NECK := 33
const VIRTUAL_PELVIS := 34
const ANGLE_COUNT := 9
const FEATURE_DIM := KEYPOINT_COUNT * 3 + ANGLE_COUNT # 108
## 关节角 (a, b, c) 三元组索引
const ANGLE_TRIPLETS := [
[KeypointFrame.LEFT_ELBOW, KeypointFrame.LEFT_SHOULDER, KeypointFrame.LEFT_HIP],
[KeypointFrame.RIGHT_ELBOW, KeypointFrame.RIGHT_SHOULDER, KeypointFrame.RIGHT_HIP],
[KeypointFrame.LEFT_SHOULDER, KeypointFrame.LEFT_ELBOW, KeypointFrame.LEFT_WRIST],
[KeypointFrame.RIGHT_SHOULDER, KeypointFrame.RIGHT_ELBOW, KeypointFrame.RIGHT_WRIST],
[KeypointFrame.LEFT_SHOULDER, KeypointFrame.LEFT_HIP, KeypointFrame.LEFT_KNEE],
[KeypointFrame.RIGHT_SHOULDER, KeypointFrame.RIGHT_HIP, KeypointFrame.RIGHT_KNEE],
[KeypointFrame.LEFT_HIP, KeypointFrame.LEFT_KNEE, KeypointFrame.LEFT_ANKLE],
[KeypointFrame.RIGHT_HIP, KeypointFrame.RIGHT_KNEE, KeypointFrame.RIGHT_ANKLE],
[KeypointFrame.NOSE, VIRTUAL_NECK, VIRTUAL_PELVIS],
]
const ANGLE_NAMES := [
"shoulder_L", "shoulder_R", "elbow_L", "elbow_R",
"hip_L", "hip_R", "knee_L", "knee_R", "spine",
]
## 一帧特征:108 维值 + 108 维权重
class FeatureVector extends RefCounted:
var values: PackedFloat32Array = PackedFloat32Array()
var weights: PackedFloat32Array = PackedFloat32Array()
var time_ms: float = 0.0
func _init() -> void:
values.resize(PoseFeatures.FEATURE_DIM)
weights.resize(PoseFeatures.FEATURE_DIM)
values.fill(0.0)
weights.fill(1.0)
func dimension() -> int:
return values.size()
## 由姿态帧构造特征向量
static func build(frame: KeypointFrame.PoseFrame, use_unmirrored: bool = true) -> FeatureVector:
var out := FeatureVector.new()
if frame == null:
return out
var points: PackedVector3Array = frame.unmirrored_points() if use_unmirrored else frame.points
var confidence: PackedFloat32Array = frame.confidence
out.time_ms = float(frame.received_at_ms)
# ---- 33 × 3 坐标 ----
for i in KEYPOINT_COUNT:
var p := points[i] if i < points.size() else Vector3.ZERO
var c := confidence[i] if i < confidence.size() else 0.0
var w := 1.0 if c >= KeypointFrame.CONFIDENCE_THRESHOLD else 0.0
out.values[i * 3] = p.x
out.values[i * 3 + 1] = p.y
out.values[i * 3 + 2] = p.z
out.weights[i * 3] = w
out.weights[i * 3 + 1] = w
out.weights[i * 3 + 2] = w
# ---- 9 个关节角 ----
var neck := _midpoint(points, KeypointFrame.LEFT_SHOULDER, KeypointFrame.RIGHT_SHOULDER)
var pelvis := _midpoint(points, KeypointFrame.LEFT_HIP, KeypointFrame.RIGHT_HIP)
var positions := _extended_positions(points, neck, pelvis)
for a in ANGLE_COUNT:
var triple: Array = ANGLE_TRIPLETS[a]
var idx := KEYPOINT_COUNT * 3 + a
out.values[idx] = _angle_cos(positions[triple[0]], positions[triple[1]], positions[triple[2]])
# 三个端点均可信时该角度才参与代价计算
var trustworthy := (
_weight_for_point(confidence, triple[0]) > 0.0
and _weight_for_point(confidence, triple[1]) > 0.0
and _weight_for_point(confidence, triple[2]) > 0.0
)
out.weights[idx] = 1.0 if trustworthy else 0.0
return out
## 33 点 + neck(33) + pelvis(34)
static func _extended_positions(points: PackedVector3Array, neck: Vector3, pelvis: Vector3) -> Array:
var out: Array = []
out.resize(VIRTUAL_PELVIS + 1)
for i in KEYPOINT_COUNT:
out[i] = points[i] if i < points.size() else Vector3.ZERO
out[VIRTUAL_NECK] = neck
out[VIRTUAL_PELVIS] = pelvis
return out
static func _midpoint(points: PackedVector3Array, a: int, b: int) -> Vector3:
var pa: Vector3 = points[a] if a < points.size() else Vector3.ZERO
var pb: Vector3 = points[b] if b < points.size() else Vector3.ZERO
return (pa + pb) * 0.5
static func _weight_for_point(confidence: PackedFloat32Array, index: int) -> float:
if index == VIRTUAL_NECK or index == VIRTUAL_PELVIS or index >= KeypointFrame.KEYPOINT_COUNT:
return 1.0
if index >= confidence.size():
return 0.0
return 1.0 if confidence[index] >= KeypointFrame.CONFIDENCE_THRESHOLD else 0.0
## 向量 ba 与 bc 夹角的余弦,落在 [-1, 1]
static func _angle_cos(a: Vector3, b: Vector3, c: Vector3) -> float:
var ba := a - b
var bc := c - b
var denom := ba.length() * bc.length()
if denom < 1e-9:
return 0.0
return clampf(ba.dot(bc) / denom, -1.0, 1.0)
## 加权欧氏距离(逐维归一化,使不同维数可比)
static func weighted_distance(a: FeatureVector, b: FeatureVector) -> float:
var dim := mini(a.values.size(), b.values.size())
if dim == 0:
return 0.0
var sum := 0.0
var weight_total := 0.0
for i in dim:
var w: float = minf(a.weights[i], b.weights[i])
if w <= 0.0:
continue
var d := a.values[i] - b.values[i]
sum += w * d * d
weight_total += w
if weight_total <= 0.0:
return 0.0
return sqrt(sum / weight_total)
## 逐维绝对差(用于调试与可视化)
static func dimension_deltas(a: FeatureVector, b: FeatureVector) -> PackedFloat32Array:
var out := PackedFloat32Array()
out.resize(mini(a.values.size(), b.values.size()))
for i in out.size():
out[i] = absf(a.values[i] - b.values[i])
return out
## 关节角名称索引 → 中文标签(UI 展示用)
static func angle_label(index: int) -> String:
match index:
0: return "左肩"
1: return "右肩"
2: return "左肘"
3: return "右肘"
4: return "左髋"
5: return "右髋"
6: return "左膝"
7: return "右膝"
8: return "躯干"
return "角度%d" % index
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class_name Scoring
extends RefCounted
## 评分规则(T-WIN-007 / T-WIN-008)
##
## DTW 给出的是「平均每步代价」c(越小越贴合)。本类把它映射成 0~100 分与等级,
## 并定义连击阈值。所有常量集中在此,便于调参与测试。
## 连击判定阈值:单帧得分 ≥ 该值即计入连击
const COMBO_THRESHOLD := 70.0
## 等级分界(含下界)
const GRADE_BANDS := [
{"min": 95.0, "grade": "S", "label": "完美"},
{"min": 85.0, "grade": "A", "label": "优秀"},
{"min": 70.0, "grade": "B", "label": "良好"},
{"min": 55.0, "grade": "C", "label": "及格"},
{"min": 0.0, "grade": "D", "label": "需努力"},
]
## 由 DTW 平均代价换算单帧得分 [0,100]
## cost == 0 → 100 分;cost >= tolerance → 0 分
static func score_from_cost(cost: float, tolerance: float) -> float:
if tolerance <= 0.0:
return 0.0
if cost <= 0.0:
return 100.0
if cost >= tolerance:
return 0.0
return (1.0 - cost / tolerance) * 100.0
## 指数滑动平均,抑制逐帧抖动
static func smooth(previous: float, current: float, alpha: float) -> float:
var a := clampf(alpha, 0.0, 1.0)
if previous == 0.0 and current > 0.0:
return current
return previous * (1.0 - a) + current * a
static func grade(score: float) -> String:
for band in GRADE_BANDS:
if score >= float(band["min"]):
return str(band["grade"])
return "D"
static func grade_label(score: float) -> String:
for band in GRADE_BANDS:
if score >= float(band["min"]):
return str(band["label"])
return "需努力"
## 展示用颜色(与 UI 主题一致)
static func grade_color(score: float) -> Color:
match grade(score):
"S": return Color("ffd166")
"A": return Color("7ae582")
"B": return Color("4ea1ff")
"C": return Color("ffb703")
_: return Color("ff6b6b")
## 结算评语
static func summary_comment(score: float) -> String:
match grade(score):
"S": return "动作几乎与示范完全同步,非常出色!"
"A": return "节奏与姿态都很到位,继续保持。"
"B": return "整体跟得上,注意手部与躯干的细节。"
"C": return "基本跟上节奏,幅度和时机还有提升空间。"
_: return "先放慢速度熟悉动作,再逐步跟上音乐节奏。"
## 由单帧结果拼装 UI 文案
static func format_result(result: Dictionary) -> String:
if result.is_empty():
return "等待姿态数据…"
return "得分 %d | 连击 %d | 进度 %d%%" % [
int(round(float(result.get("score", 0.0)))),
int(result.get("combo", 0)),
int(round(float(result.get("progress", 0.0)) * 100.0)),
]
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