Enhanced minetest.line_of_sight()

[stu]

Looking recently at kaeza's kutils.find_pointed_thing() code just
gave me the idea that it could be very helpful for some mods if minetest.line_of_sight()
would return the actual blocking node position instead of just false.

From what I can make of ServerEnvironment::line_of_sight() it should not cost any additional
overhead to do so.

I would submit a pull request but I am not familiar with how this routine integrates with
the lua api. I also know that this has just recently been fixed 'again' so I wouldn't want
to mess things up.

[rubenwardy]

It would have to be a separate api function, as returning an object would equate to true, which will break old mods.

[PilzAdam]

It would have to be a separate api function, as returning an object would equate to true, which will break old mods.

We could also return false, blocking_node

[stu]

It would have to be a separate api function, as returning an object would equate to true, which will break old mods.

How long has this method been available? I was thinking it was a fairly recent addition but could well be mistaken.
If it has been around a while then I do see your point as it was (until very recently) returning nil.

We could also return false, blocking_node

But wouldn't returning a table still be interpreted as not-nil? It's a real pity as i can think of a number of potential uses for
such a silmple modification.

[PilzAdam]

We could also return false, blocking_node

But wouldn't returning a table still be interpreted as not-nil? It's a real pity as i can think of a number of potential uses for
such a silmple modification.

Not a table, in Lua functions can have more than one return value.

[stu]

Not a table, in Lua functions can have more than one return value.

Oh, I was not even aware you could do that, maybe it's time I properly read the lua docs.

So does that mean that the following code would still work assuming a false condition?

Your phone or window isn't wide enough to display the code box. If it's a phone, try rotating it to landscape mode.

Code: Select all

if not minetest.line_of_sight(p1, p2) then
    --code here
end


btw, I think returning the actual position of the node would be more useful than the node
itself as it would be possible to determine the node from the position but not vice-versa.

Edit: This seems to explain things quite well http://www.lua.org/pil/5.1.html
I guess it should be ok in that case.

[rubenwardy]

I used it in capture the flag 3 months ago.

[stu]

I used it in capture the flag 3 months ago.

I just checked, minetest.line_of_sight() was introduced in the 0.4.7 release so there are probably
not that many 'old' mods that use it.

[stu]

Ok, this appears to work https://gist.github.com/stujones11/7881082

I am sure there are other ways it could have been done but this seemed like the least intrusive to me.
I would be interested to hear any comments on the style before I waste my time submitting a pull request.

[celeron55]

Make it a pull request; it seems fine and that way it gets more attention.

[stu]

celeron55, If you are ok with the code then I will certainly do that

cheers!