minetest/builtin/game/knockback.lua

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-- 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)