Taking damage on TP

[seem0nster]

Client version: 1.8.9
Server OS: Linux

Expected behavior

To do "/home" from 0,75,0 - -200,25,150 Without taking damage while teleporting.

Actual behavior

Taking damage if the coordinates you are teleporting to are below the Y coord you are at

Maybe the solution

Setting the velocity to 0 while teleporting.

English might be Horrible

[Debucquoy Anthony tonitch]

Confirmed: I tried with a simple /tp and the same happen.
I also noticed that when you /tp ~ ~50 ~ you don't get fall damages.
That is strange I think this is supposed to be handled by https://github.com/cuberite/cuberite/blob/master/src/Entities/Player.cpp#L2530-L2559 which is called by Player:TeleportToCords()

[Debucquoy Anthony tonitch]

duped tho : #5286

[seem0nster]

hmm, i think it is because it handles fall damage like if you go from Y- 80 to Y- 20, it takes where you fell to, not how long you have spent in the air.

English may be horrible.

[NiLSPACE]

Fall damage is currently not handled well. We currently don't look at the y-speed of the player to calculate the damage amount but by looking at the current y-level compared to the previous on-ground y-level:

cuberite/src/Entities/Pawn.cpp

Lines 434 to 463 in 20d5cf0

 const auto FallHeight = m_LastGroundHeight - GetPosY(); 
 auto Damage = static_cast<int>(FallHeight - 3.0); 
  
 const auto Below = POS_TOINT.addedY(-1); 
 const auto BlockBelow = (cChunkDef::IsValidHeight(Below)) ? GetWorld()->GetBlock(Below) : static_cast<BLOCKTYPE>(E_BLOCK_AIR); 
  
 if ((Damage > 0) && !FallDamageAbsorbed) 
 { 
 	if (IsElytraFlying()) 
 	{ 
 		Damage = static_cast<int>(static_cast<float>(Damage) * 0.33); 
 	} 
  
 	if (BlockBelow == E_BLOCK_HAY_BALE) 
 	{ 
 		Damage = std::clamp(static_cast<int>(static_cast<float>(Damage) * 0.2), 1, 20); 
 	} 
  
 	// Fall particles 
 	// TODO: falling on a partial (e.g. slab) block shouldn't broadcast particles of the block below 
 	GetWorld()->BroadcastParticleEffect( 
 		"blockdust", 
 		GetPosition(), 
 		{ 0, 0, 0 }, 
 		(Damage - 1.f) * ((0.3f - 0.1f) / (15.f - 1.f)) + 0.1f,  // Map damage (1 - 15) to particle speed (0.1 - 0.3) 
 		static_cast<int>((Damage - 1.f) * ((50.f - 20.f) / (15.f - 1.f)) + 20.f),  // Map damage (1 - 15) to particle quantity (20 - 50) 
 		{ { BlockBelow, 0 } } 
 	); 
  
 	TakeDamage(dtFalling, nullptr, Damage, static_cast<float>(Damage), 0);