1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
//! `foot-slide` — during stance (the foot near its lowest height), a
//! locomotion clip's foot must move consistently with the clip's
//! declared travel: at `speed_mps` relative to the character for an
//! in-place (treadmill) clip, or planted in the world for a
//! root-motion clip. Deviation is the skate that runtime IK and blend
//! band-aids exist to hide.
//!
//! The research-grade check of the catalog (DESIGN.md §12): contact
//! detection is heuristic, so it ships as a warning with generous
//! defaults; judged only on clips that declare `speed_mps`.
use crate::check::{Check, CheckCtx};
use crate::checks::root_motion_gap;
use crate::evaluation::{
Applicability, CheckOutput, CoverageGap, CoverageGapCode, EvaluationScope, EvaluationScopeCode,
};
use crate::finding::{Finding, Severity};
use crate::metrics::root_motion_speed_mps;
use crate::profile::Role;
/// A foot within this height of its per-clip minimum is in contact.
pub const DEFAULT_CONTACT_HEIGHT_M: f64 = 0.03;
/// Allowed deviation of stance-foot speed from the expected travel.
pub const DEFAULT_MAX_SLIDE_MPS: f64 = 0.3;
pub struct FootSlide;
impl Check for FootSlide {
fn id(&self) -> &'static str {
"foot-slide"
}
fn applicability(&self, ctx: &CheckCtx) -> Applicability {
// Foot-slide needs the travel mode (root/hips) to know whether
// a planted or sweeping foot is correct; individual missing
// feet are handled per-foot in `evaluate`.
if ctx
.clip_expectations()
.iter()
.any(|expectations| expectations.speed_mps.is_some())
{
Applicability::Applicable
} else {
Applicability::NotApplicable
}
}
fn evaluate(&self, ctx: &CheckCtx) -> CheckOutput {
let mut findings = Vec::new();
let mut evaluated_scopes = Vec::new();
let mut gaps = Vec::new();
let settings = ctx.config.check_settings(self.id());
let contact_height = settings
.contact_height_m
.unwrap_or(DEFAULT_CONTACT_HEIGHT_M);
let max_slide = settings.max_slide_mps.unwrap_or(DEFAULT_MAX_SLIDE_MPS);
for (index, clip) in ctx.doc.clips.iter().enumerate() {
let Some(pin) = ctx.expectations(index).speed_mps else {
continue;
};
if let Some(gap) = root_motion_gap(ctx.roles) {
gaps.push(gap.scope(
EvaluationScope::new(EvaluationScopeCode::FOOT_STANCE).subject(&clip.name),
));
continue;
}
let Some(grid) = ctx.grid(index) else {
gaps.push(
CoverageGap::new(
CoverageGapCode::MEASUREMENT_UNAVAILABLE,
"clip is too short to sample foot stance",
)
.scope(
EvaluationScope::new(EvaluationScopeCode::FOOT_STANCE).subject(&clip.name),
),
);
continue;
};
let Some(root_speed) = root_motion_speed_mps(&grid, ctx.roles) else {
gaps.push(
CoverageGap::new(
CoverageGapCode::MEASUREMENT_UNAVAILABLE,
"root-motion speed could not be measured",
)
.scope(
EvaluationScope::new(EvaluationScopeCode::FOOT_STANCE).subject(&clip.name),
),
);
continue;
};
// Treadmill clip: the stance foot must sweep backward at the
// declared speed. Root-motion clip: it must stay planted.
let expected_speed = if root_speed >= 0.5 { 0.0 } else { pin.value };
// Foot first, toe as fallback — matching `foot_cycle_metrics`
// so a rig that resolves only toe roles is still judged (#57).
for (side_roles, label) in [
([Role::LeftFoot, Role::LeftToe], "left"),
([Role::RightFoot, Role::RightToe], "right"),
] {
let scope = if label == "left" {
EvaluationScope::new(EvaluationScopeCode::LEFT_FOOT_STANCE)
} else {
EvaluationScope::new(EvaluationScopeCode::RIGHT_FOOT_STANCE)
}
.subject(&clip.name);
let Some(foot) = side_roles.iter().find_map(|&r| ctx.roles.get(r)) else {
gaps.push(
CoverageGap::new(
CoverageGapCode::ROLES_UNRESOLVED,
format!("{label} foot/toe role not resolved"),
)
.scope(scope),
);
continue;
};
let frames = grid.frame_count();
evaluated_scopes.push(scope);
let heights: Vec<f64> = (0..frames)
.map(|f| grid.model_position(f, foot).y as f64)
.collect();
let ground = heights.iter().copied().fold(f64::MAX, f64::min);
let mut worst: Option<(f64, usize)> = None;
for f in 1..frames {
if heights[f] > ground + contact_height
|| heights[f - 1] > ground + contact_height
{
continue; // not a stance step
}
let dt = (grid.times[f] - grid.times[f - 1]) as f64;
if dt <= 0.0 {
continue;
}
let a = grid.model_position(f - 1, foot);
let b = grid.model_position(f, foot);
let dx = (b.x - a.x) as f64;
let dz = (b.z - a.z) as f64;
let speed = dx.hypot(dz) / dt;
let slide = (speed - expected_speed).abs();
if slide > max_slide && worst.is_none_or(|(w, _)| slide > w) {
worst = Some((slide, f));
}
}
if let Some((slide, frame)) = worst {
findings.push(
Finding::new(
self.id(),
Severity::Warning,
format!(
"{label} foot skates during stance: speed deviates \
{slide:.2} m/s from the expected {expected_speed:.2} m/s \
(cap {max_slide:.2}) — foot plants will slip at runtime"
),
)
.clip(&clip.name)
.bone(ctx.doc.skeleton.bones[foot].name.clone())
.time(grid.times[frame])
.measured(slide)
.expected(max_slide),
);
}
}
}
CheckOutput::from_coverage(findings, evaluated_scopes, gaps)
}
}