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feat(physics): phys_step_top - the highest top a foot could step up to, walls left out (what CharacterGround.top_at asks)

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Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Orkun ÇAKILKAYA 2026-09-26 23:43:40 +03:00
parent 204ec93c5a
commit 1c814464c5
5 changed files with 66 additions and 2 deletions
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37
packages/ludic.physics/native/shim/jph_queries.inl
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@ -79,3 +79,40 @@ JPH_SHIM int jph_push(void *w, float x, float z, float r, float y0, float y1, in
out[1] = pz;
return int(hits.mHits.size());
}
// the highest top under an upright body r wide at (x, z) that a foot at `feet` could stand on or
// step up to: a thing whose top is above feet + reach is a wall and is left out, whatever else is
// there. Each candidate's surface is found by letting a ball r across down onto it alone.
// -FLT_MAX when there is nothing.
JPH_SHIM float jph_step_top(void *w, float x, float z, float r, float feet, float reach, int mask) {
World *ww = static_cast<World *>(w);
float limit = feet + reach;
float y0 = feet - 1.0f, y1 = limit + 0.05f;
float half = (y1 - y0) * 0.5f;
CylinderShape column(half, r, 0.0f);
column.SetEmbedded();
AllHitCollisionCollector<CollideShapeCollector> hits;
MaskFilter f(mask);
ww->sys.GetNarrowPhaseQuery().CollideShape(&column, Vec3::sOne(), RMat44::sTranslation(RVec3(x, y0 + half, z)),
CollideShapeSettings(), RVec3::sZero(), hits, {}, f);
hits.Sort();
float best = -FLT_MAX;
SphereShape ball(r);
ball.SetEmbedded();
float from = limit + r + 0.01f;
RShapeCast cast = RShapeCast::sFromWorldTransform(&ball, Vec3::sOne(), RMat44::sTranslation(RVec3(x, from, z)),
Vec3(0.0f, y0 - from, 0.0f));
for (const CollideShapeResult &h : hits.mHits) {
BodyLockRead lock(ww->sys.GetBodyLockInterface(), h.mBodyID2);
if (!lock.Succeeded()) continue;
const Body &b = lock.GetBody();
float top = float(b.GetWorldSpaceBounds().mMax.GetY());
if (top > limit + 1.0e-4f) continue;
ClosestHitCollisionCollector<CastShapeCollector> c;
b.GetTransformedShape().CastShape(cast, ShapeCastSettings(), RVec3::sZero(), c);
float y = c.HadHit() ? float(c.mHit.mContactPointOn2.GetY()) : top;
if (y > top) y = top;
if (y > best) best = y;
}
return best;
}