Handle retail park streams and spline headers across all disc maps

crates/skate-game/src/grind_world/spline.rs

@@ -102,8 +102,15 @@ pub(crate) fn primitives(map: Option<&SkateMap>) -> Result<Vec<Primitive>,String
         let [a,b,c,d] = coefficients;
         let end = std::array::from_fn(|j| (a[j]+b[j])+(c[j]+d[j]));
         let length: f32 = (0..3).map(|j| (end[j]-d[j]).powi(2)).sum();
-        if !length.is_finite() || length <= 0.000001 {
-            return Err(format!("Spline segment {i} has a degenerate contact chord"));
+        if !length.is_finite() {
+            return Err(format!("Spline segment {i} has a non-finite contact chord"));
+        }
+        if length <= 0.000001 {
+            // Retail Downtown contains duplicate knots and sub-millimetre
+            // chords. They cannot provide a usable contact direction. Keep
+            // their cubic records and links in build(), but omit them from
+            // this adapter's independent contact-primitive array.
+            continue;
         }
         result.push(Primitive { start:d,end,owner:((word(r) as u64)<<32)|word(r+4) as u64 });
     }

docs/installation.md

@@ -46,3 +46,19 @@ game process and closes the current session so physics and render resources
 are recreated. A fresh launch defaults to University. Development checkouts
 with `assets/private/game.json` retain their existing local assets and default
 test world; `--assets DIRECTORY` also selects a prepared asset set explicitly.
+
+## Conversion checks
+
+The direct converter was checked against an extracted Xbox 360 disc containing
+the three main districts, Skate School, and six separately stored parks:
+Black Box, Downtown Skate Park, Industrial Skate Park, Maloof, Mega Park and
+Start Park. All ten outputs passed the runtime's asset, spline and collision
+load checks. This does not establish visual or gameplay parity, and the
+original ISO extraction step still needs checking with an ISO.
+
+Two retail spline details needed corrections. Downtown contains duplicate
+knots and sub-millimetre chords. The native cubic records remain intact;
+only unusable contact primitives are omitted. Skate School's first spline
+header word is `0001 0002`, meaning two rails, not 65,538. TU3 function
+`82C1EEF0` reads the count with `lhz +2` (also at `82C1EFBC`). The reader now
+uses that halfword and retains the other halfword in the map metadata.

tools/asset_pipeline/install.py

@@ -98,7 +98,9 @@ def convert_map(archive,work,maps,stage,game_exe,log,report):
     manifest_path=prepare(stream_directory=stream,output_root=district_work/'intermediate',
         utt_root=TOOLS/'vendor/utt',district_name=district,map_name=label,
         package_name='Skate 3 owned disc',cache_format='skate3-rust-map-v1',
-        texture_stream_names=('Tex',),excluded_normal_texture_ids=EXCLUDED_NORMAL_TEXTURE_IDS)
+        # Smaller parks keep their textures in Pres rather than a Tex stream.
+        texture_stream_names=('Tex',) if any(stream.glob('cTex_*.xsf')) else (),
+        excluded_normal_texture_ids=EXCLUDED_NORMAL_TEXTURE_IDS)
     collision=district_work/'collision.rwcmset'
     build_archive(manifest_path,collision)
     final=maps/(label+'.skate')

tools/vendor/university/tools/vanilla_map_extraction/tools/retail_grind_splines.py

@@ -168,8 +168,11 @@ def decode_grind_splines(data: bytes) -> list[dict[str, object]]:
         ):
             raise ValueError("RX2 spline section extends beyond the file")
 
-        rail_count, segment_count, rail_table, segment_table = (
-            struct.unpack_from(">4I", data, section_offset)
+        # TU3 GrindData::Add (82C1EEF0) reads lhz +2, including its loop
+        # bound at 82C1EFBC. The first halfword is not part of the count:
+        # Skate School has header 0001 0002, two rails, table end 0x50.
+        header_halfword, rail_count, segment_count, rail_table, segment_table = (
+            struct.unpack_from(">HH3I", data, section_offset)
         )
         expected_segment_table = (
             SPLINE_HEADER_SIZE + rail_count * SPLINE_RAIL_SIZE
@@ -271,6 +274,7 @@ def decode_grind_splines(data: bytes) -> list[dict[str, object]]:
                 {
                     "section_index": record_index,
                     "section_offset": section_offset,
+                    "section_header_halfword": header_halfword,
                     "rail_index": rail_index,
                     "spline_id": f"0x{spline_id:016X}",
                     "type_signature": f"0x{type_signature:016X}",