Fix incorrect implementation of tunnel loco speed (#1551)

Fix incompatiblity with CnCNet/yrpp-spawner#27

Author: ZivDero

src/Misc/Hooks.BugFixes.cpp

@@ -923,12 +923,14 @@ DEFINE_HOOK(0x71ADE4, TemporalClass_Release_SlaveTargetFix, 0x5)
 // which means it didn't consider the actual speed of the unit. Now we check it and the units won't get stuck
 // even at high speeds - NetsuNegi
 
-DEFINE_HOOK(0x7295C5, TunnelLocomotionClass_ProcessDigging_SlowdownDistance, 0x9)
+DEFINE_HOOK(0x72958E, TunnelLocomotionClass_ProcessDigging_SlowdownDistance, 0x8)
 {
 	enum { KeepMoving = 0x72980F, CloseEnough = 0x7295CE };
 
 	GET(TunnelLocomotionClass* const, pLoco, ESI);
-	GET(int const, distance, EAX);
+
+	auto& currLoc = pLoco->LinkedTo->Location;
+	int distance = (int) CoordStruct{currLoc.X - pLoco->Coords.X, currLoc.Y - pLoco->Coords.Y,0}.Magnitude() ;
 
 	// The movement speed was actually also hardcoded here to 19, so the distance check made sense
 	// It can now be customized globally or per TechnoType however - Starkku
@@ -943,9 +945,14 @@ DEFINE_HOOK(0x7295C5, TunnelLocomotionClass_ProcessDigging_SlowdownDistance, 0x9
 	speed = pLoco->LinkedTo->GetCurrentSpeed();
 	pType->Speed = maxSpeed;
 
-	TunnelLocomotionClass::TunnelMovementSpeed = speed;
-
-	return distance >= speed + 1 ? KeepMoving : CloseEnough;
+	if (distance > speed)
+	{
+		REF_STACK(CoordStruct, newLoc, STACK_OFFSET(0x40, -0xC));
+		double angle = -Math::atan2(currLoc.Y - pLoco->Coords.Y, pLoco->Coords.X - currLoc.X);
+		newLoc = currLoc + CoordStruct { int((double)speed * Math::cos(angle)), int((double)speed * Math::sin(angle)), 0 };
+		return 0x7298D3;
+	}
+	return 0x7295CE;
 }
 
 DEFINE_HOOK(0x75BD70, WalkLocomotionClass_ProcessMoving_SlowdownDistance, 0x9)