### migration to mt 5.0/5.2

There are the issues Tignasse Verte mentionned: Adding `placer` in `register_functions.lua` 
(related commit for minenux are commit a996d5ac709446322d6c6261c21e5f0752a6aeeb )
and replacing the two occourances of `nodeupdate` with `minetest.check_for_falling`.

Other changes are necessary because I changed (and had to change) quite a lot 
in `mg_villages` internally recently. If you want to get further with running 
the game under newer versions of MT, replace the versions of `cottages`, `handle_schematics` 
and `mg_villages` AdventureTest comes with with the newest versions.

Then, remove the line `mg_villages.on_generated(minp,maxp,seed)` in 
`adventuretest/register_functions.lua`. This may have an impact on quests the 
old explorer is handling out, but if you ignore these for now, the world ought to be usable.

Comment out the file/content of `mg/fill_chests.lua` for now as that requires 
a few adjustments for filling the chests with the right content, and that's a bit 
too much to write here in an inconvenient forum post.

You won't see any villagers spawning because their spawn blocks are not placed. 
My first attempts there ended in a severe overcrowding of villagers. Needs 
finetuning/understanding what BrandonReese did to keep it balanced. But then, 
this seems to be an open issue on Github as well...

Mobs will likely not work very well. A lot changed regarding them. 
They certainly could use an update as well - as could the goblins. I'm sure the witches 
from the same modder would feel welcome in the AdventureTest universe, too.

###### now the changes in fact:

DFeniks wrote:
2020-01-07 10:02:08: ERROR[Main]: ServerError: AsyncErr: Lua: finishGenRuntime error from mod 'default' in callback item_OnPlace(): ...enturetest/mods/adventuretest/register_functions.lua:101: attempt to index local 'placer' (a nil value)

Reason on server-side :

Here are the changes made on server-side, concerning item_OnPlace, for the 5.X.X :
https://dev.minetest.net/Changelog,
0.4.16 → 5.0.0 , Released March 4th 2019 / Server-side / User interface / Items

Set placer to nil instead of a non-functional one in item_OnPlace (DTA7)
Here is why, you may have a nil placer. One issue had been logged :
https://github.com/minetest/minetest/issues/6487
place_node crashes the game because of nil player #6487

Here is the commit corresponding :
https://github.com/minetest/minetest_game/pull/1907/commits/73c5339adb8ff93328f5439bf842767b71e0ce6c
Add nil checks for placer #1907

Reason in the mod :
For Adventure Test, in `dungeons.lua`, you have line 33 a `minetest.register_on_generated()`, 
in it, you have, line 161, a call of `minetest.place_node()`.

In `register_functions.lua`, you have a `minetest.register_on_placenode(adventuretest_placenode)`, 
so the call of `place_node()` redirect to `adventuretest_placenode()`.
In the commit, I have found an example of change (a nil check) that can be done 
in `adventuretest_placenode()`.

What to do :
Go to :
games\adventuretest\mods\adventuretest
There, change the file :
`register_functions.lua` replace the line 101 (`if placer:is_player() then`) with :

```
if placer and placer:is_player() then
```

0.4.16 → 5.0.0 :
`nodeupdate()` was removed. Fix: replace with `minetest.check_for_falling`.

In Adventuretest I have found 2 calls of `nodeupdate()` (may be there is more).
When it have been called, I got a crash :
`AsyncErr: ServerThread::run Lua: Runtime error from mod 'default' in callback LuaABM::trigger(): ...32\bin\..\games\adventuretest\mods\default/functions.lua:385: attempt to call global 'nodeupdate' (a nil value)`

What to do :
Change the file
`games\adventuretest\mods\default\functions.lua`
replace the line 385 (nodeupdate(p0)) with :
`minetest.check_for_falling(p0)`

Then, change the file `games\adventuretest\mods\doors\init.lua` replace the line 374 with :
`minetest.check_for_falling({x = pos.x, y = pos.y + 1, z = pos.z})`

### Fiel of view for monsters vs characters

From https://forum.minetest.net/viewtopic.php?p=182737#p182737

If it helps any, here is the in_fov code from mobs redo mod that works (self is mob, pos is player position and self.fov is set to 90, self.rotate is usually 0 for front facing mobs):
CODE: SELECT ALL

```
in_fov = function(self,pos)
	-- checks if POS is in self's FOV
	local yaw = self.object:getyaw() + self.rotate
	local vx = math.sin(yaw)
	local vz = math.cos(yaw)
	local ds = math.sqrt(vx^2 + vz^2)
	local ps = math.sqrt(pos.x^2 + pos.z^2)
	local d = { x = vx / ds, z = vz / ds }
	local p = { x = pos.x / ps, z = pos.z / ps }
	local an = ( d.x * p.x ) + ( d.z * p.z )

	a = math.deg( math.acos( an ) )
```

Thank you everyone, especially TeTpaAka and Nore. All problems were at last solved, and the code now reports the angle difference between entities like it should! You get 0* when standing right in front of the mob, 90* when standing parallel to either side, 180* when standing behind... whereas flying up or down now accounts pitch correctly on top of that.

Here is the final and fully functional version. I hope it will be helpful to more people than just me, if anyone ever needs a simple and efficient FOV scanner for Minetest.

```
local function in_fov (pos1, pos2, yaw, pitch, fov)
	local function yaw2vec (yaw, pitch)
		-- we must invert the yaw for x to keep the result from inverting when facing opposite directions (0* becoming 180*)
		return {x = math.sin(-yaw) * math.cos(pitch), y = math.sin(pitch), z = math.cos(yaw) * math.cos(pitch)}
	end

	local function dotproduct (v1, v2)
		return ((v1.x * v2.x) + (v1.y * v2.y) + (v1.z * v2.z))
	end

	local function angle (v1, v2)
		return math.deg(math.acos(dotproduct(v1, v2) / (vector.length(v1) * vector.length(v2))))
	end

	local v = vector.subtract(pos2, pos1)
	print(angle(yaw2vec(yaw, pitch), v))
end
```

here is the final version of the function which I'll be including in my mod, simplified to only 5 lines of code but with the same result:
CODE: SELECT ALL

```
-- returns the angle difference between pos1 and pos2, as seen from pos1 at the specified yaw and pitch
function pos_to_angle (pos1, pos2, yaw, pitch)
	-- note: we must invert the yaw for x in yaw_vec, to keep the result from inverting when facing opposite directions (0* becoming 180*)
	local yaw_vec = {x = -math.sin(yaw) * math.cos(pitch), y = math.sin(pitch), z = math.cos(yaw) * math.cos(pitch)}
	local pos_subtract = vector.subtract(pos2, pos1)
	local pos_dotproduct = (yaw_vec.x * pos_subtract.x) + (yaw_vec.y * pos_subtract.y) + (yaw_vec.z * pos_subtract.z)
	local angle = math.deg(math.acos(pos_dotproduct / (vector.length(yaw_vec) * vector.length(pos_subtract))))
	return angle
end
```