View source for Help:Patching the motorcycle area checks

Because of arbitrary, hardcoded limitations, the Master Cycle Zero cannot be used in some areas. This article lists and documents checks that must be patched to remove usage restrictions.

Most of them are located in the MotorcycleMgr.

== Check ==
The game uses the current climate for the area check<ref>[https://github.com/leoetlino/botw-re-notes/blob/2c0b98c1d5e4cb35a11d4a3ea764323432a596ea/tools/check_master_cycle_ok_areas Extracted check from Switch 1.5.0]</ref>:

* ✅ HyrulePlainClimate
* ✅ NorthHyrulePlainClimate
* ✅ HebraFrostClimate
* ✅ TabantaAridClimate
* ✅ FrostClimate
* 🚫 GerudoDesertClimate
* ✅ GerudoPlateauClimate
* ✅ EldinClimateLv0
* ✅ TamourPlainClimate
* ✅ ZoraTemperateClimate
* ✅ HateruPlainClimate
* ✅ FiloneSubtropicalClimate
* ✅ SouthHateruHumidTemperateClimate
* 🚫 EldinClimateLv1
* 🚫 EldinClimateLv2
* ✅ DarkWoodsClimat
* ✅ LostWoodClimate
* ✅ GerudoFrostClimate
* ✅ KorogForest
* 🚫 GerudoDesertClimateLv2

== Patching ==
* On Switch, read the rest of the article to understand what to patch.
* On Wii U, the checks are implemented in the exact same way (which makes sense since it's the same codebase), but only a single instruction has to be patched because the Wii U compiler is not quite as good at inlining functions. Simply patch the instruction at <code>0x02A32A30</code> to <code>li r3, 1</code>.

== Technical details ==
''Note: the addresses below are only valid for Switch 1.5.0. Other versions (on Switch or Wii U) can be patched in a similar way, though.''

=== Disappearing when entering a blacklisted climate ===

Called from the Motorcycle AI root code.

<source lang="cpp">if ( v6 && !MotorcycleMgr::motorcycleCanBeUsed(v6, (float *)&v68, 0LL) )  // 0x71004ADF18
  goto triggerDisappear;</source>
Either change the condition to be always false, or change <code>MotorcycleMgr::motorcycleCanBeUsed</code> (preferred to avoid side effects):

<source lang="cpp">bool MotorcycleMgr::motorcycleCanBeUsed(MotorcycleMgr* this, Vec3 *positions, __int64 a3) // 0x7100679D10
{
  if ( (a3 || (a3 = ActorSystem::sInstance->field_C0) != 0)
    && (*(__int64 (__fastcall **)(__int64))(*(_QWORD *)a3 + 0x180LL))(a3) & 1 )
  {
    return false;
  }
  if ( WorldMgr::sInstance
         && (v5 = (u64)WorldMgr::getClimateNum(WorldMgr::sInstance, positions) - 5, v5 <= 14) )
  {
    return (0x3CFEu >> v5) & 1;
  }
  return true;
}</source>
Patch:

<source lang="armasm">.text:0000007100679D84                 AND             W0, W8, #1</source>
To:

<source lang="armasm">.text:0000007100679D84                 MOV             W0, #1</source>

=== Rune UI/sound effect ===

Same climate based check as above, but done in a different MotorcycleMgr function. Just change:

<source lang="armasm">.text:0000007100679650 TBNZ            W8, #0, loc_710067965C</source>
to:

<source lang="armasm">.text:0000007100679650 B               loc_710067965C</source>
=== Refusing to spawn when in a blacklisted climate ===

==== Check 1 ====

Deep in some MotorcycleMgr function, called from the PlayerNormal AI:

<source lang="cpp">else if ( !WorldMgr::sInstance
       || (v7 = (unsigned __int64)WorldMgr::getClimateNum(WorldMgr::sInstance, (float *)v4) - 5, v7 > 0xE)
       || (0x3CFEu >> v7) & 1 )
{
  v8 = (*(__int64 (**)(void))(**(_QWORD **)(HavokAI::sInstance->navMeshQueryReqPool + 0x1A0LL) + 0x30LL))();
  ...
}</source>
Patch:

<source lang="armasm">.text:0000007100679BA8                 CBZ             X0, loc_7100679BD8</source>
to:

<source lang="armasm">.text:0000007100679BA8                 B               loc_7100679BD8</source>
so that the game always executes the code inside of the if block.

==== Check 2 ====

Found in another MotorcycleMgr member function and also called from the PlayerNormal AI code.

<source lang="cpp">bool MotorcycleMgr::checkUsable2(MotorcycleMgr *this, __int64 a2)
{
  if ( this->someFlag == 1 )
    return 0;
  float* v4 = this->gap12C;
  MotorcycleMgr::x_7(this, (float *)this->gap12C, (__int64)&this->field_134 + 4);
  if ( a2 || (a2 = ActorSystem::sInstance->field_C0) != 0 )
  {
    if ( (*(__int64 (__fastcall **)(__int64))(*(_QWORD *)a2 + 0x180LL))(a2) & 1 )
      return 0;
  }
  if ( !WorldMgr::sInstance )
    return 1;
  unsigned int climateNumMinus5 = WorldMgr::getClimateNum(WorldMgr::sInstance, v4) - 5;
  return ( climateNumMinus5 > 14 || (0x3CFEu >> climateNumMinus5) & 1 );
}</source>
Change:

<source lang="armasm">.text:000000710067B5FC                 CBZ             X0, loc_710067B62C</source>
to:

<source lang="armasm">.text:000000710067B5FC                 B               loc_710067B62C</source>
to make the game always return “true”.

=== Disappearing when being away from the motorcycle ===

This is checked by Motorcycle AI root code (at 0x71004ADF28).

<source lang="cpp">v40 = (float *)PlayerInfo::getPlayerPos(PlayerInfo::sInstance);
if ( (float)((float)((float)(*(float *)&v68 - *v40) * (float)(*(float *)&v68 - *v40))
           + (float)((float)(*(float *)&v70 - v40[2]) * (float)(*(float *)&v70 - v40[2]))) > (float)(**(float **)&this->_4abuf[8] * **(float **)&this->_4abuf[8]) )
  goto triggerDisappear;</source>
It is easy to change this condition to be always false.

=== Other checks ===

There are a few more conditions for spawning the motorcycle<ref>0x7100678E80 in Switch 1.5.0</ref>; however patching them is not recommended as they are implemented for good reasons.

==== Actor check ====

If the actor cannot be loaded, the game will not allow the player to use the motorcycle and will show the regular “You can’t use that here” message.

==== 6 or 7 other checks ====

The MotorcycleMgr function at 0x7100678E80 (which can be identified with a xref to "GameROMMotorcycle") calls 6 member functions that must all return true; otherwise, the motorcycle cannot be used.

The first 4 functions appear to be using the Havok AI NavMesh system. Something called “motorcycle shape cast” is used in the 3 other functions.

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