HUD_GetHullBounds BugFix Patch.md

How to patch

Open your cstrike/cl_dlls/client.dll with hex editor (for example WinHex) and replace bytes 8B4C240433C02BC87406497403497505B801000000C3 with 837C240401750B8B44240CC7400800000042B001C3C3. In WinHex you can open the replace dialog with Ctrl+Alt+H

Info for developers

The original function:

int HUD_GetHullBounds(int hullnum, float* mins, float* maxs)
{
  return (hullnum == 0 || hullnum == 1 || hullnum == 2) ? 1 : 0;
}

// 22 bytes
8B 4C 24 04       mov     ecx, [esp+4]
33 C0             xor     eax, eax
2B C8             sub     ecx, eax
74 06             jz      short NonLargeHull
49                dec     ecx
74 03             jz      short NonLargeHull
49                dec     ecx
75 05             jnz     short Exit
NonLargeHull:
B8 01 00 00 00    mov     eax, 1
Exit:
C3                retn

The patched function (bool is OK here, because engine expects just != 0):

bool HUD_GetHullBounds(int hullnum, float* mins, float* maxs)
{
  if (hullnum == 1)
    maxs[2] = 32.0f;
  return true;
}

// 21 bytes
83 7C 24 04 01        cmp [esp+4], 1
75 0B                 jne NonCrouch
8B 44 24 0c           mov eax, [esp+0Ch]
C7 40 08 00 00 00 42  mov [eax+8], 42000000h
NonCrouch:
B0 01                 mov al, 1
C3                    retn

Another dirty way to patch this function:

// 22 bytes
XX XX XX XX           mov eax, [esp+4]
40                    inc eax
XX XX XX              cmp eax, 2
75 0B                 jne NonCrouch
8B 44 24 0c           mov eax, [esp+0Ch]
C7 40 08 00 00 00 42  mov [eax+8], 42000000h
NonCrouch:
C3                    retn