From 1e3b1cabaea62ef0e30ce8a478fb8418aa835229 Mon Sep 17 00:00:00 2001
From: salmonik <salmonik@tuta.io>
Date: Mon, 26 Oct 2026 16:25:28 +0100
Subject: ESP: derive skeleton core from hitbox bone paths (fixes unnamed
 ValveBiped bones)

---
 src/bones.cpp | 63 +++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 42 insertions(+), 21 deletions(-)

(limited to 'src/bones.cpp')

diff --git a/src/bones.cpp b/src/bones.cpp
index a9c6887..35756c2 100644
--- a/src/bones.cpp
+++ b/src/bones.cpp
@@ -91,8 +91,10 @@ struct BoneEntry {
   void *ent;
   double stamp;
   bool valid;
+  bool humanoid;
   const StudioHdr *hdr;
   int count;
+  bool core[MAX_BONES];
   Matrix3x4 mats[MAX_BONES];
 };
 
@@ -182,23 +184,41 @@ static bool hitbox_world(const BoneEntry *e, const Hitbox &b, Vector &out) {
   return true;
 }
 
-// HL2 humanoids (combine, metrocop, citizen, zombie, ...) use the ValveBiped
-// skeleton. Draw only the core chain: pelvis/spine/neck/head, clavicle to
-// hand, thigh to foot. Fingers, toes and extra model bones (e.g. the headcrab
-// on a zombie) are skipped.
-static bool core_bone_name(const char *n) {
-  if (!n || strncasecmp(n, "ValveBiped.Bip01_", 17) != 0)
-    return false;
-  if (contains_ci(n, "Finger") || contains_ci(n, "Toe") ||
-      contains_ci(n, "Headcrab"))
-    return false;
-  static const char *tokens[] = {"Pelvis",   "Spine",  "Neck",  "Head1",
-                                 "Clavicle", "UpperArm", "Forearm", "Hand",
-                                 "Thigh",    "Calf",   "Foot",  nullptr};
-  for (int i = 0; tokens[i]; i++)
-    if (contains_ci(n, tokens[i]))
-      return true;
-  return false;
+// HL2 humanoids use the ValveBiped skeleton, but many of its bone names are
+// stripped (the zombie's spine/legs/left arm are unnamed). Instead of matching
+// names, mark the paths from every hitbox bone up to the root: that yields the
+// chest/spine, arms and legs, while fingers/toes have no hitboxes and the
+// headcrab's HC_* hitbox is skipped explicitly.
+static void build_core_mask(BoneEntry *e) {
+  e->humanoid = false;
+  for (int i = 0; i < e->count; i++) {
+    const char *n = bone_name_raw(e->hdr, i);
+    if (n && strncasecmp(n, "ValveBiped.Bip01_", 17) == 0) {
+      e->humanoid = true;
+      break;
+    }
+  }
+  memset(e->core, 0, sizeof(e->core));
+  if (!e->humanoid)
+    return;
+  const HitboxSet *s = hitbox_set0(e->hdr);
+  if (!s)
+    return;
+  const Hitbox *boxes = hitboxes(s);
+  for (int i = 0; i < s->numhitboxes; i++) {
+    int b = boxes[i].bone;
+    if (b < 0 || b >= e->count)
+      continue;
+    const char *bn = bone_name_raw(e->hdr, b);
+    if (bn && (contains_ci(bn, "Headcrab") || contains_ci(bn, "HC_") ||
+               contains_ci(bn, "Finger") || contains_ci(bn, "Toe")))
+      continue;
+    int cur = b;
+    for (int guard = 0; cur >= 0 && cur < e->count && guard < 64; guard++) {
+      e->core[cur] = true;
+      cur = bone_at(e->hdr, cur)->parent;
+    }
+  }
 }
 
 static void dump_hitboxes(const BoneEntry *e) {
@@ -297,6 +317,7 @@ bool bones_update(int idx, void *ent) {
 
   e->hdr = hdr;
   e->count = hdr->numbones;
+  build_core_mask(e);
   e->valid = true;
   e->stamp = now;
   if (g_logged < 4) {
@@ -333,18 +354,18 @@ int bone_parent(int idx, int bone) {
 
 bool bone_is_skeleton_core(int idx, int bone) {
   BoneEntry *e = find_entry(idx);
-  if (!e || !e->valid || bone < 0 || bone >= e->count)
+  if (!e || !e->valid || !e->humanoid || bone < 0 || bone >= e->count)
     return false;
-  return core_bone_name(bone_name_raw(e->hdr, bone));
+  return e->core[bone];
 }
 
 int bone_nearest_core_parent(int idx, int bone) {
   BoneEntry *e = find_entry(idx);
-  if (!e || !e->valid || bone < 0 || bone >= e->count)
+  if (!e || !e->valid || !e->humanoid || bone < 0 || bone >= e->count)
     return -1;
   int p = bone_at(e->hdr, bone)->parent;
   for (int guard = 0; p >= 0 && p < e->count && guard < 64; guard++) {
-    if (core_bone_name(bone_name_raw(e->hdr, p)))
+    if (e->core[p])
       return p;
     p = bone_at(e->hdr, p)->parent;
   }
-- 
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