fix(physics): port retail slope landing stop

tools/analyze_269_slope_stop_capture.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python3
+"""Summarize an ACDREAM_CAPTURE_PLAYER_QUANTA JSONL for issue #269."""
+
+from __future__ import annotations
+
+import argparse
+import json
+import math
+from pathlib import Path
+from typing import Any
+
+
+def vector(value: dict[str, Any]) -> tuple[float, float, float]:
+    return float(value["x"]), float(value["y"]), float(value["z"])
+
+
+def length(value: tuple[float, float, float]) -> float:
+    return math.sqrt(sum(component * component for component in value))
+
+
+def horizontal(value: tuple[float, float, float]) -> float:
+    return math.hypot(value[0], value[1])
+
+
+def subtract(
+    left: tuple[float, float, float],
+    right: tuple[float, float, float],
+) -> tuple[float, float, float]:
+    return tuple(a - b for a, b in zip(left, right, strict=True))
+
+
+def scale(
+    value: tuple[float, float, float],
+    scalar: float,
+) -> tuple[float, float, float]:
+    return tuple(component * scalar for component in value)
+
+
+def input_active(record: dict[str, Any]) -> bool:
+    state = record["input"]
+    return any(
+        bool(state[key])
+        for key in (
+            "forward",
+            "backward",
+            "strafeLeft",
+            "strafeRight",
+            "turnLeft",
+            "turnRight",
+            "jump",
+        )
+    )
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("capture", type=Path)
+    parser.add_argument(
+        "--tail",
+        type=int,
+        default=45,
+        help="quanta printed after the final directional-input release",
+    )
+    args = parser.parse_args()
+
+    with args.capture.open("r", encoding="utf-8") as stream:
+        records = [json.loads(line) for line in stream if line.strip()]
+
+    if not records:
+        print("capture contains no physics quanta")
+        return 2
+
+    release_indices = [
+        index
+        for index in range(1, len(records))
+        if input_active(records[index - 1]) and not input_active(records[index])
+    ]
+    start = release_indices[-1] if release_indices else max(0, len(records) - args.tail)
+    stop = min(len(records), start + args.tail)
+
+    print(
+        "seq dt walk(pre/post) |v|pre |v|fric |v|commit "
+        "horizCommit rootDelta collision fsf"
+    )
+    for record in records[start:stop]:
+        dt = float(record["dt"])
+        pre = record["preIntegration"]
+        post_integration = record["postIntegration"]
+        post_commit = record["postCommit"]
+        pre_velocity = vector(pre["velocity"])
+        integrated_velocity = vector(post_integration["velocity"])
+        acceleration = vector(pre["acceleration"])
+        friction_velocity = subtract(
+            integrated_velocity,
+            scale(acceleration, dt),
+        )
+        commit_velocity = vector(post_commit["velocity"])
+        transient_pre = int(pre["transientState"])
+        transient_post = int(post_commit["transientState"])
+        pre_walk = (transient_pre & 0x2) != 0
+        post_walk = (transient_post & 0x2) != 0
+        root_delta = length(vector(record["rootAndManagerDelta"]))
+        resolve = record["resolve"]
+        collision = "yes" if resolve["collisionNormalValid"] else "no"
+        print(
+            f'{record["sequence"]:5d} {dt:0.5f} '
+            f"{int(pre_walk)}/{int(post_walk)} "
+            f"{length(pre_velocity):8.4f} "
+            f"{length(friction_velocity):8.4f} "
+            f"{length(commit_velocity):8.4f} "
+            f"{horizontal(commit_velocity):8.4f} "
+            f"{root_delta:8.4f} {collision:>3s} "
+            f'{post_commit["framesStationaryFall"]:d}'
+        )
+
+    if release_indices:
+        print(f"\nlast directional-input release: sequence {records[start]['sequence']}")
+    else:
+        print("\nno directional-input release edge found; showing capture tail")
+    print(f"records: {len(records)}, displayed: {stop - start}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())