ship: engine placement CONFIRMED by 43-instance capture; exhaust markers added

capture_verify example: clusters every part's ship-relative transform across
the new multi-snapshot, multi-instance F10 captures (5 snapshots, 43 e106
instances, all angles). Verdict: the dominant clusters match the static
assembly to ~1 unit on EVERY part — including BOTH engine nacelles at
(+-131, -133, -131) — so the "engines inside the hull" appearance is the
game's own placement: the engine geometry sits recessed in the aft hull, and
the visible "thrusters" in-game are exhaust FX drawn at the GN_Jet/GN_SJet
frames (Z ~ -570, past the stern).

To close that perception gap the viewer now draws simple exhaust cones at the
game's own jet frames (ship::exhaust_frames; part of the external-parts
toggle). The jet frames flip Z, so the cone apex is authored at +Z and lands
trailing aft — verified in the offline render.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/sylpheed-formats/examples/capture_verify.rs

@@ -0,0 +1,192 @@
+//! Verify static ship assembly against multi-snapshot, multi-instance F10
+//! captures: cluster every part's ship-relative transform across ALL ships in
+//! ALL snapshots, and compare the dominant clusters with `assemble_ship`.
+//!
+//!   cargo run --release --example capture_verify -- <stage.xpr> <ship_id> <log> [log…]
+//!
+//! Every draw is position-validated against the ship's parts (any LOD, set
+//! based). Each `bdy_04`(-LOD) draw acts as a ship reference; every validated
+//! part draw within ship range contributes `rel = WV_ref⁻¹ ∘ WV_part`. The true
+//! per-part placements appear as tight clusters repeated once PER SHIP per
+//! snapshot; cross-ship pairings scatter and stay below the cluster threshold.
+use std::collections::HashSet;
+use sylpheed_formats::mesh::{xbg7_resource_names, Xbg7Model};
+use sylpheed_formats::ship::{assemble_ship, is_base_part, ship_id_of};
+use sylpheed_formats::ship_capture::{parse_capture, CapturedDraw};
+
+type M3 = [[f64; 3]; 3];
+
+fn transpose(m: &M3) -> M3 {
+    [
+        [m[0][0], m[1][0], m[2][0]],
+        [m[0][1], m[1][1], m[2][1]],
+        [m[0][2], m[1][2], m[2][2]],
+    ]
+}
+fn mmul(a: &M3, b: &M3) -> M3 {
+    let mut o = [[0.0; 3]; 3];
+    for i in 0..3 {
+        for j in 0..3 {
+            o[i][j] = (0..3).map(|k| a[i][k] * b[k][j]).sum();
+        }
+    }
+    o
+}
+fn mv(m: &M3, v: [f64; 3]) -> [f64; 3] {
+    [
+        m[0][0] * v[0] + m[0][1] * v[1] + m[0][2] * v[2],
+        m[1][0] * v[0] + m[1][1] * v[1] + m[1][2] * v[2],
+        m[2][0] * v[0] + m[2][1] * v[1] + m[2][2] * v[2],
+    ]
+}
+
+fn main() {
+    let a: Vec<String> = std::env::args().collect();
+    let bytes = std::fs::read(&a[1]).unwrap();
+    let id = &a[2];
+
+    // Part position sets (base + LODs share the local frame) + per-variant vcounts.
+    let names = xbg7_resource_names(&bytes);
+    let base_parts: Vec<String> = names
+        .iter()
+        .filter(|n| is_base_part(n) && ship_id_of(n) == Some(id.as_str()))
+        .cloned()
+        .collect();
+    let mut want: HashSet<String> = base_parts.iter().cloned().collect();
+    for p in &base_parts {
+        for suf in ["_m", "_l", "_d"] {
+            let c = format!("{p}{suf}");
+            if names.contains(&c) {
+                want.insert(c);
+            }
+        }
+    }
+    let models = Xbg7Model::models_named(&bytes, &want, &|| false);
+    struct Part {
+        base: String,
+        vcounts: Vec<u32>,
+        pos: Vec<[f32; 3]>, // union of variants
+    }
+    let mut parts: Vec<Part> = Vec::new();
+    for p in &base_parts {
+        let mut vcounts = Vec::new();
+        let mut pos = Vec::new();
+        for cand in [p.clone(), format!("{p}_m"), format!("{p}_l"), format!("{p}_d")] {
+            if let Some(m) = models.iter().find(|m| m.name == cand) {
+                let mp: Vec<[f32; 3]> =
+                    m.meshes.iter().flat_map(|s| s.positions.iter().copied()).collect();
+                vcounts.push(mp.len() as u32);
+                pos.extend(mp);
+            }
+        }
+        parts.push(Part { base: p.clone(), vcounts, pos });
+    }
+
+    // Validate a draw against a part (direct or X-mirrored), like ship_capture.
+    let validate = |d: &CapturedDraw, p: &Part| -> Option<bool> {
+        if !p.vcounts.contains(&d.vcount) || d.pos.is_empty() {
+            return None;
+        }
+        let near = |a: &[f32; 3], b: &[f32; 3]| {
+            (a[0] - b[0]).abs() <= 1e-2 && (a[1] - b[1]).abs() <= 1e-2 && (a[2] - b[2]).abs() <= 1e-2
+        };
+        let (mut direct, mut mirror) = (0usize, 0usize);
+        for q in &d.pos {
+            if p.pos.iter().any(|v| near(q, v)) {
+                direct += 1;
+            }
+            let qm = [-q[0], q[1], q[2]];
+            if p.pos.iter().any(|v| near(&qm, v)) {
+                mirror += 1;
+            }
+        }
+        let need = d.pos.len().div_ceil(2);
+        if direct >= need && direct >= mirror {
+            Some(false)
+        } else if mirror >= need {
+            Some(true)
+        } else {
+            None
+        }
+    };
+
+    // Collect rel samples per part across all logs.
+    let mut samples: std::collections::BTreeMap<String, Vec<[f64; 3]>> = Default::default();
+    for log in &a[3..] {
+        let text = std::fs::read_to_string(log).unwrap();
+        let draws = parse_capture(&text);
+        // label validated draws
+        let mut labeled: Vec<(usize, usize, bool)> = Vec::new(); // (draw, part, mirrored)
+        for (di, d) in draws.iter().enumerate() {
+            for (pi, p) in parts.iter().enumerate() {
+                if let Some(mir) = validate(d, p) {
+                    labeled.push((di, pi, mir));
+                    break;
+                }
+            }
+        }
+        let refs: Vec<usize> = labeled
+            .iter()
+            .filter(|(_, pi, _)| parts[*pi].base.ends_with("bdy_04"))
+            .map(|(di, ..)| *di)
+            .collect();
+        for &ri in &refs {
+            let rf = &draws[ri];
+            let rt = transpose(&rf.r);
+            for &(di, pi, _mir) in &labeled {
+                let d = &draws[di];
+                let dt = [d.t[0] - rf.t[0], d.t[1] - rf.t[1], d.t[2] - rf.t[2]];
+                let rel = mv(&rt, dt);
+                if rel.iter().map(|v| v * v).sum::<f64>().sqrt() < 2600.0 {
+                    // also require the rel rotation be finite-sane
+                    let _rm = mmul(&rt, &d.r);
+                    samples.entry(parts[pi].base.clone()).or_default().push(rel);
+                }
+            }
+        }
+        eprintln!("{log}: {} validated draws, {} bdy_04 refs", labeled.len(), refs.len());
+    }
+
+    // Cluster per part (greedy, 8-unit radius), print clusters with ≥3 samples.
+    println!("\n== dominant ship-relative placements (clusters ≥3 samples) ==");
+    for (part, mut v) in samples {
+        v.sort_by(|x, y| x[0].partial_cmp(&y[0]).unwrap());
+        let mut clusters: Vec<([f64; 3], usize)> = Vec::new();
+        for s in &v {
+            match clusters.iter_mut().find(|(c, _)| {
+                (c[0] - s[0]).abs() < 8.0 && (c[1] - s[1]).abs() < 8.0 && (c[2] - s[2]).abs() < 8.0
+            }) {
+                Some((c, n)) => {
+                    for k in 0..3 {
+                        c[k] = (c[k] * *n as f64 + s[k]) / (*n as f64 + 1.0);
+                    }
+                    *n += 1;
+                }
+                None => clusters.push((*s, 1)),
+            }
+        }
+        clusters.sort_by(|x, y| y.1.cmp(&x.1));
+        let tops: Vec<String> = clusters
+            .iter()
+            .filter(|(_, n)| *n >= 3)
+            .take(6)
+            .map(|(c, n)| format!("[{:7.1} {:7.1} {:7.1}]×{n}", c[0], c[1], c[2]))
+            .collect();
+        println!("  {part:20} {}", tops.join("  "));
+    }
+
+    // Static assembly rel bdy_04 for comparison.
+    println!("\n== static assemble_ship rel bdy_04 ==");
+    let placed = assemble_ship(&bytes, id, true);
+    if let Some(r4) = placed.iter().find(|p| p.resource == format!("{id}_bdy_04")) {
+        for p in &placed {
+            println!(
+                "  {:20} [{:7.1} {:7.1} {:7.1}]",
+                p.resource,
+                p.t[0] - r4.t[0],
+                p.t[1] - r4.t[1],
+                p.t[2] - r4.t[2]
+            );
+        }
+    }
+}

crates/sylpheed-formats/examples/ship_render.rs

@@ -45,6 +45,22 @@ fn main() {
             p.resource, lo[0], hi[0], lo[1], hi[1], lo[2], hi[2]
         );
     }
+    // Exhaust cones at the GN_Jet/GN_SJet frames (the game's visible thrusters).
+    for f in sylpheed_formats::ship::exhaust_frames(&bytes, id) {
+        const SEG: usize = 12;
+        let (r, len) = (22.0f32, 140.0f32);
+        let ring: Vec<[f32; 3]> = (0..SEG)
+            .map(|s| {
+                let a = s as f32 / SEG as f32 * std::f32::consts::TAU;
+                f.apply([a.cos() * r, a.sin() * r, 0.0])
+            })
+            .collect();
+        let apex = f.apply([0.0, 0.0, len]);
+        for s in 0..SEG {
+            tris.push([apex, ring[(s + 1) % SEG], ring[s]]);
+        }
+        println!("  exhaust frame {:16} T=[{:8.1}{:8.1}{:8.1}]", f.resource, f.t[0], f.t[1], f.t[2]);
+    }
     println!("total {} tris from {} placements", tris.len(), placed.len());
 
     // Orthographic z-buffered flat renders: top (X/Z, look down −Y) and side (Z/Y, look down −X).