aephysics.hull: quickhull and the half-edge hull

README.md

@@ -28,7 +28,8 @@ so a test written against the reference reads the same here.
 | `aephysics.math` | vectors, quaternions, transforms, 3x3 matrices, bounding boxes, segment distances, inertia helpers, the deterministic atan2/cos/sin | done, `test_math.ae` (6M checks) |
 | `aephysics.core` | bit set, id pool, hash set, arrays, the stack and arena allocators | done, `test_core.ae` (100k checks) |
 | `aephysics.dynamic_tree` | the bounding volume hierarchy under the broad phase: SAH insertion, rotations, enlarge, sweep refit, partial rebuild in depth-first order, box / closest / ray / swept-box queries | done, `test_dynamic_tree.ae` (12k checks); [same tree as the reference, ray cast 1.9x its time](bench/RESULTS.md#dynamic_tree) |
-| `aephysics.collision` | hull (quickhull), GJK distance and shape cast, contact manifolds, triangle mesh, height field, shapes with mass properties, ray and shape casts | next |
+| `aephysics.hull` | quickhull with face merging, the half-edge hull with its mass properties, box / cylinder / cone / rock hulls, clone-and-transform with mirroring, support functions, ray cast, the 2D hull | done, `test_hull.ae` (438 checks); [same hulls as the reference, 1.6-2x its time](bench/RESULTS.md#hull) |
+| `aephysics.collision` | GJK distance and shape cast, contact manifolds, triangle mesh, height field, shapes with mass properties, ray and shape casts | next |
 | `aephysics.dynamics` | bodies, contacts, the constraint graph, islands, the Soft Step solver, joints (spherical, revolute, prismatic, distance, motor, weld, wheel), sensors, the character mover, the world | |
 | `aephysics` | the public API | |
 

aephysics/core/module.ae

@@ -23,7 +23,7 @@ exports (
     BitSet, IdPool, HashSet, IntArray, Buffer, Stack, Arena,
     alloc, free_bytes, alloc_count, bytes_in_use,
     is_power_of_2, bounding_power_of_2, round_up_power_of_2, lower_power_of_2_exponent,
-    clz32, ctz32, ctz64, pop_count64, lsr,
+    clz32, ctz32, ctz64, pop_count64, lsr, lsr32,
     bitset_create, bitset_destroy, bitset_set_count_and_clear, bitset_grow, bitset_union,
     bitset_set, bitset_set_grow, bitset_clear, bitset_get, bitset_count, bitset_bytes,
     idpool_create, idpool_destroy, idpool_alloc, idpool_free, idpool_count, idpool_capacity,
@@ -125,6 +125,9 @@ pop_count64(block: long) -> int {
 
 // A logical shift right of a long by 1..63: what an unsigned shift does,
 // where the language's shift is arithmetic.
+// The logical shift right of an int, for 0 < n < 32.
+lsr32(x: int, n: int) -> int { return (x >> n) & ((1 << (32 - n)) - 1) }
+
 lsr(value: long, shift: int) -> long {
     if shift <= 0 { return value }
     if shift >= 64 { return 0 }