feat(Core/Movement): Improved pathfinding, collisions and movements (#4220)

Npc positioning
Implemented slope check to avoid unwanted climbing for some kind of movements (backwards, repositioning etc.)
Implemented backwards movement
Re-implemented circle repositioning algorithm (smartest than retail, but with the same feeling)
Fixed random position of summoned minions
Improved pet following movement. Also, they attack NPC from behind now. Thanks to @Footman

Swimming creatures
Fixed max_z coordinate for swimming creatures. Now only part of their body is allowed to be out of the water level
Fixed pathfinder for swimming creatures creating shortcuts for specific segments, now they swim underwater to reach the seashore instead of flying above the water level.
Creatures with water InhabitType but no swimming flag now, when not in combat, will walk on water depth instead of swimming. Thanks @jackpoz for the original code
UNIT_FLAG_SWIMMING in UpdateEnvironmentIfNeeded to show the swimming animation correctly when underwater
Implemented HasEnoughWater check to avoid swimming creatures to go where the water level is too low but also to properly enable swimming animation only when a creature has enough water to swim.

Walking creatures
Extended the DetourNavMeshQuery adding area cost based on walkability (slope angle + source height) to find better paths at runtime instead of completely remove them from mmaps
improve Z height in certain conditions (see #4205, #4203, #4247 )

Flying creatures
Rewriting of the hover system
Removed hacks and improved the UpdateEnvironmentIfNeeded. Now creatures can properly switch from flying to walk etc.
Spells
LOS on spell effect must be calculated on CollisionHeight and HitSpherePoint instead of position coords.
Improved position for object/creature spawned via spells
Improved checks for Fleeing movements (fear spells)

Other improvements
Implemented method to calculate the CollisionWidth from dbc (used by repositioning algorithm etc.)
Improved raycast and collision checks

Co-authored-by: Footman <p.alexej@freenet.de>
Co-authored-by: Helias <stefanoborzi32@gmail.com>
Co-authored-by: Francesco Borzì <borzifrancesco@gmail.com>
Co-authored-by: Kitzunu <24550914+Kitzunu@users.noreply.github.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/src/server/game/AI/CreatureAI.cpp b/src/server/game/AI/CreatureAI.cpp
index 5150f4cd75..615c05af81 100644
--- a/src/server/game/AI/CreatureAI.cpp
+++ b/src/server/game/AI/CreatureAI.cpp
@@ -257,6 +257,40 @@ bool CreatureAI::_EnterEvadeMode()
     return true;
 }
 
+void CreatureAI::MoveCircleChecks()
+{
+    Unit *victim = me->GetVictim();
+
+    if (
+        !victim ||
+        !me->IsFreeToMove() || me->HasUnitMovementFlag(MOVEMENTFLAG_ROOT) ||
+        !me->IsWithinMeleeRange(victim) || me == victim->GetVictim() ||
+        (victim->GetTypeId() != TYPEID_PLAYER && !victim->IsPet())  // only player & pets to save CPU
+    )
+    {
+        return;
+    }
+
+    me->GetMotionMaster()->MoveCircleTarget(me->GetVictim());
+}
+
+void CreatureAI::MoveBackwardsChecks() {
+    Unit *victim = me->GetVictim();
+
+    if (
+        !victim ||
+        !me->IsFreeToMove() || me->HasUnitMovementFlag(MOVEMENTFLAG_ROOT) ||
+        (victim->GetTypeId() != TYPEID_PLAYER && !victim->IsPet())
+    )
+    {
+        return;
+    }
+
+    float moveDist = me->GetMeleeRange(victim) / 2;
+
+    me->GetMotionMaster()->MoveBackwards(victim, moveDist);
+}
+
 Creature* CreatureAI::DoSummon(uint32 entry, const Position& pos, uint32 despawnTime, TempSummonType summonType)
 {
     return me->SummonCreature(entry, pos, summonType, despawnTime);