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Add player knockback on punch to builtin

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sfan5 committed Jul 16, 2019
1 parent cf64054 commit 291e7730cf24ba5081f10b5ddbf2494951333827
Showing with 56 additions and 0 deletions.
  1. +1 −0 builtin/game/init.lua
  2. +46 −0 builtin/game/knockback.lua
  3. +9 −0 doc/lua_api.txt
@@ -33,5 +33,6 @@ dofile(gamepath .. "features.lua")
dofile(gamepath .. "voxelarea.lua")
dofile(gamepath .. "forceloading.lua")
dofile(gamepath .. "statbars.lua")
dofile(gamepath .. "knockback.lua")

profiler = nil
@@ -0,0 +1,46 @@
-- can be overriden by mods
function core.calculate_knockback(player, hitter, time_from_last_punch, tool_capabilities, dir, distance, damage)
if damage == 0 or player:get_armor_groups().immortal then
return 0.0
end

local m = 8
-- solve m - m*e^(k*4) = 4 for k
local k = -0.17328
local res = m - m * math.exp(k * damage)

if distance < 2.0 then
res = res * 1.1 -- more knockback when closer
elseif distance > 4.0 then
res = res * 0.9 -- less when far away
end
return res
end

local function vector_absmax(v)
local max, abs = math.max, math.abs
return max(max(abs(v.x), abs(v.y)), abs(v.z))
end

core.register_on_punchplayer(function(player, hitter, time_from_last_punch, tool_capabilities, unused_dir, damage)
if player:get_hp() == 0 then
return -- RIP
end

-- Server::handleCommand_Interact() adds eye offset to one but not the other
-- so the direction is slightly off, calculate it ourselves
local dir = vector.subtract(player:get_pos(), hitter:get_pos())
local d = vector.length(dir)
if d ~= 0.0 then
dir = vector.divide(dir, d)
end

local k = core.calculate_knockback(player, hitter, time_from_last_punch, tool_capabilities, dir, d, damage)

local kdir = vector.multiply(dir, k)
if vector_absmax(kdir) < 1.0 then
return -- barely noticeable, so don't even send
end

player:add_player_velocity(kdir)
end)
@@ -5019,6 +5019,15 @@ Misc.
of the creative mode setting, checks for "sneak" to set the `invert_wall`
parameter and `prevent_after_place` set to `true`.

* `minetest.calculate_knockback(player, hitter, time_from_last_punch,
tool_capabilities, dir, distance, damage)`
* Returns the amount of knockback applied on the punched player.
* Arguments are equivalent to `register_on_punchplayer`, except the following:
* `distance`: distance between puncher and punched player
* This function can be overriden by mods that wish to modify this behaviour.
* You may want to cache and call the old function to allow multiple mods to
change knockback behaviour.

* `minetest.forceload_block(pos[, transient])`
* forceloads the position `pos`.
* returns `true` if area could be forceloaded

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