A way to detect when a player jumps

[Zughy]

Problem

There doesn't seem to be any detection for when the player jumps. I tried checking the block beneath if it's equal to air on minetest.register_globalstep, but it gets called several times if I don't put some sort of boolean, adding unnecessary weight to the code. And, even if there is an easier way to do it, it doesn't seem intuitive for me at all (I checked both in the dev wiki and in the txt file)

Solutions

Player:is_on_air() (or is on ground, floor, or minetest.is_player_on_air(player) etc., whatever) like Godot does with is_on_floor(). Maybe checking if the collision box is actually colliding with something (idk how it works the C++ builtin part, sorry)
EDIT by paramat: See lua code posted in #9631 (comment)
The issue author is actually trying to detect when a player jumps, which is very different to detecting "air" below a player.

Additional info

It looks like back in 2017 something asked about something pretty similar already without any answer, idk if it can help https://forum.minetest.net/viewtopic.php?f=47&t=17646

[Andrey2470T]

Actually, yes, there are no any API ways to check what nodes are beneath, except a workaround (calculate a position of the player bottom and retrieving the node by minetest.get_node at each step).

I think it would be nice to get info about colliding result with other ones along to each global axle. Maybe is it a worth to add a callback like e.g. 'after_collide' for entity and node which a collision result table is passed to?

[sorcerykid]

Part of the reason this will be rather difficult to implement iirc, is because player physics are handled client-side. So that would require the server duplicate the calculations for player motion just to provide an API for scripts to check whether the player is in air, which is extremely infrequent. Now in fairness, I could be mistaken. I know there is cheat-detection code which likely performs these calculations anyway. So hopefully a core-dev can better clarify the technicalities.

[paramat]

It seems easy to implement, but would of course be serverside so slightly out of sync with what the player is doing clientside, depending on network delay.
I do not think the issue author is requesting this be clientside and instantly responsive.
So it seems this is a request for an API that just checks the node below for being "air", or perhaps "airlike" drawtype.
Would it be much faster being an API, relative to using 'get_node' in Lua?

[paramat]

I tried checking the block beneath if it's equal to air on minetest.register_globalstep, but it gets called several times if I don't put some sort of boolean, adding unnecessary weight to the code

You need to code this to only check every few globalsteps, not every globalstep.
Checking 1 node is lightweight code, so i do not understand the complaint of intensive code.
If the API exists you would have to run the check just as frequently. As an API it might be a little faster but not significantly.
So am i right in assuming you are requesting this purely for the convenience of not coding it in Lua?

[SmallJoker]

Duplicate of #3918

EDIT: Not directly duplicate: This issue is not about a callback, and limited to Y+ collisions.
Not as generic as the other request, but would be faster approach due to limited callback frequency.

Please note that even the client doesn't know whether it's standing on ground. For example: #1460 and the obscure #6959.

[Zughy]

You need to code this to only check every few globalsteps, not every globalstep.
Checking 1 node is lightweight code, so i do not understand the complaint of intensive code.
So am i right in assuming you are requesting this purely for the convenience of not coding it in Lua?

Yes, because I stated before

even if there is an easier way to do it, it doesn't seem intuitive for me at all

I don't want to disrespect anyone's job because I honestly think what you're all doing is amazing and also because being a developer is not my job nor I studied for it, but info are scattered in at least three different sites and I often find myself going full trial and error to understand how something exactly works, it's... frustrating. So in short yes, I don't know how to reproduce it on Lua and I think it'd help a lot of people having about my same level of knowledge

[Zughy]

This was my take in Lua by the way:

local players_jumping = {} --KEY: player, VALUE: boolean

minetest.register_globalstep(function(dtime)

  for pl_name, bool in pairs(players_jumping) do

    local pl = minetest.get_player_by_name(pl_name)

    if pl:get_player_control().jump and pl:get_hp() > 0 and not players_jumping[pl_name] then

      local pos = pl:get_pos()
      local pos_feet = {x = pos.x, y = pos.y-0.501, z = pos.z}
      local drawtype = minetest.registered_nodes[minetest.get_node(pos_feet).name]["drawtype"]

      if drawtype ~= "normal" and drawtype ~= "glasslike" and drawtype ~= "nodebox" then return end
      players_jumping[pl_name] = true

      --DO STUFF

      minetest.after(0.2, function()
        players_jumping[pl_name] = false
      end)
    end

  end
end)

There are still two consistent issues with the code:

1. if I stand on the edge of a block enough to have my feet floating on air, it won't be triggered because the block beneath my feet is indeed air. Have I to check every corner of the colliding box? Is it even possible via Lua?
2. if I consequently jump as in "climbing" a Y +1 steep, the second jump won't trigger the sound

That is, of course, if my method isn't plain wrong

[Zughy]

Sparing work to core devs, according to labels