minetest-mm/mods/hot_air_balloons/movement.lua

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2021-01-23 12:24:04 +01:00
--localize global functions
local vector_new = vector.new
local math_hypot = math.hypot
local atan = math.atan
local cos = math.cos
local sin = math.sin
local abs = math.abs
local pi = math.pi
local min = math.min
--max speed settings
local max_ballooning_vertical_speed = 1
local max_ballooning_horizontal_speed = 3
local function is_water_is_air(pos)
local node_name = minetest.get_node(pos).name
return minetest.get_item_group(node_name, "water") > 0,
node_name == "air"
end
local function get_vertical_acceleration(self)
local heat = self.heat
local vel_y = self.object:getvelocity().y
local acc_candidate = heat / 1000 - 0.5
--enforce max speed
if vel_y > max_ballooning_vertical_speed
and acc_candidate * vel_y > 0
then
return 0
else
return acc_candidate
end
end
--if balloon is submerged
local function float_up(self, vel)
self.submerged = true
vel.y = 1
return vel
end
local function swim(self, vel)
--allow controls, allow up
local pos = self.object:get_pos()
--keep y constant or rising
local acc_y = get_vertical_acceleration(self)
if self.submerged or acc_y < 0
then
self.submerged = false
vel.y = 0
return 0, vel
else
return acc_y, vel
end
end
local tau = pi * 2
--returns the radian equivalent of a in the range [0, tau)
local function to_radian(a)
if a < 0
then
return to_radian(a + tau)
elseif a >= tau
then
return to_radian(a - tau)
else
return a
end
end
--decides which is the shortest way to rotate towards where the player is looking
local function get_rotate_direction(a, b)
return to_radian(a - b) < to_radian(b - a)
end
--rotates the balloon towards where the player is looking
local pi_192ths = pi / 192 --radians to turn each step
local function rotate(self, player)
-- + pi so it finishes rotating when looking towards where the player is looking
local player_yaw = player:get_look_horizontal() + pi
local self_yaw = self.object:getyaw()
if get_rotate_direction(player_yaw, self_yaw)
then
self.object:setyaw(to_radian(self_yaw - pi_192ths))
else
self.object:setyaw(to_radian(self_yaw + pi_192ths))
end
end
--takes wasd and turns it into a 2d vector
local pi_halves = pi / 2
function get_direction(right, left, up, down)
local inline, cross = 0, 0
local move = right or left or up or down
if left then cross = 1 end
if right then cross = cross - 1 end
if up then inline = 1 end
if down then inline = inline - 1 end
local arg
if inline < 0
then
return atan(cross / inline) + pi, move
elseif inline > 0
then
return atan(cross / inline), move
else
return pi_halves * cross, move
end
end
--[[
space to rotate where the player is looking
wasd to apply acceleration
shift to let out hot air, cooling the balloon
]]
local function handle_control(self, vel)
if not self.pilot
then
return 0, 0
end
local player = minetest.get_player_by_name(self.pilot)
if not player --player left, balloon should get deleted
then
return 0, 0
end
local control = player:get_player_control()
if control.sneak --lowering heat quickly
then
local heat = self.heat - 30
if heat < 0
then
self.heat = 0
else
self.heat = heat
end
end
if control.jump --rotate towards player yaw
then
rotate(self, player)
end
--taking direction from get_direction
--and turning it into radians.
--if max speed is reached, only acceleration in the opposite direction is applied.
local dir_radians, move = get_direction(control.right, control.left, control.up, control.down)
if move and math_hypot(vel.x, vel.z)
then
dir_radians = dir_radians + player:get_look_horizontal()
local x, z = -sin(dir_radians), cos(dir_radians)
if math_hypot(vel.x, vel.z) > max_ballooning_horizontal_speed
then
if x * vel.x > 0
then
x = 0
end
if z * vel.z > 0
then
z = 0
end
end
return x, z
end
return 0, 0
end
--[[handle movement in different cases
movement restrictions:
-on ground: only vertical movement
-on water: free movement, though vertical only if up
-submerged: free movement, vertical goes up automatically
-in air: completely free movement
]]
return function(self)
local pos_in = self.object:get_pos()
local pos_under = vector_new(pos_in.x, pos_in.y - 0.1, pos_in.z)
local on_water, in_air = is_water_is_air(pos_under)
local acc = vector_new(0, 0, 0)
local vel = self.object:getvelocity()
if is_water_is_air(pos_in) --if submerged
then
vel = float_up(self, vel)
acc.x, acc.z = handle_control(self, vel)
self.object:setvelocity(vel)
elseif on_water --if on water
then
acc.y, vel = swim(self, vel)
self.object:setvelocity(vel)
acc.x, acc.z = handle_control(self, vel)
elseif in_air
then
--allow controls and height change
acc.y = get_vertical_acceleration(self)
acc.x, acc.z = handle_control(self, vel)
else --if on ground
--only allow height change
acc.y = get_vertical_acceleration(self)
vel.x = 0
vel.z = 0
self.object:setvelocity(vel)
end
self.object:setacceleration(acc)
end