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phys = {}
local world = {}
phys.world = world
world.boxes = {}
world.layers = {}
-- There are a few primary physics layers:
--
-- * Hard: for hard collisions that do not allow things in whatsoever
-- * Soft: for collisions that push other things away over time
-- * Player_Hurtbox: collision box that hurts the player
-- * Player_Hitbox: collision box from the player that damages things
-- * Enemy_Hurtbox: collision box that hurts enemies
-- * Enemy_Hitbox: collision box from an enemy that damages things
--
-- You can use whatever physics layer you want, but these are the standard ones
local function aabb_x(ax, aw, bx, bw)
return ax < bx + bw and bx < ax + aw
end
local function aabb_y(ay, ah, by, bh)
return ay < by + bh and by < ay + ah
end
local function aabb(ax, ay, aw, ah, bx, by, bw, bh)
return
ax < bx + bw and bx < ax + aw and
ay < by + bh and by < ay + ah
end
local function add_box_to_layers(box)
for _, layer in ipairs(box.layers) do
if not world.layers[layer] then
world.layers[layer] = {}
end
table.insert(world.layers[layer], box)
end
end
phys.Box = {}
phys.Box.__index = phys.Box
function phys.Box.new(
x, y,
width, height,
opts
)
opts = opts or {}
local self = setmetatable({}, phys.Box)
self.x = x
self.y = y
self.offsetx = opts.offsetx or 0
self.offsety = opts.offsety or 0
self.width = width
self.height = height
self.layers = opts.layers or {"hard"}
self.mask = opts.mask or {}
self.touching_down = false
self.touching_up = false
self.touching_vertically = false
self.touching_left = false
self.touching_right = false
self.touching_horizontally = false
add_box_to_layers(self)
return self
end
function phys.Box:get_rect()
return
self.x + self.offsetx,
self.y + self.offsety,
self.width,
self.height
end
function phys.Box:update(velx, vely, dt)
local resx = self.x + velx * dt
local resy = self.y + vely * dt
local small_side = math.min(self.width, self.height)
local steps = math.ceil(vec_len(velx * dt, vely * dt) / small_side)
self.touching_down = false
self.touching_up = false
self.touching_vertically = false
self.touching_left = false
self.touching_right = false
self.touching_horizontally = false
-- this block is fat. much like a certain croatian...
for i=1, steps do
local p = i / steps
local boxx = resx + self.offsetx + velx * dt * p
local boxy = resy + self.offsety + vely * dt * p
for _, layer in ipairs(self.mask) do
for _, other in ipairs(world.layers[layer] or {}) do
if other ~= self then
local ox = other.x + other.offsetx
local oy = other.y + other.offsety
if aabb(
boxx, boxy, self.width, self.height,
ox, oy, other.width, other.height
) then
if aabb_x(self.x + self.offsetx, self.width, ox, other.width) then
if vely > 0 then
resy = oy - self.height - self.offsety
self.touching_down = true
else
resy = oy + other.height - self.offsety
self.touching_up = true
end
self.touching_vertically = true
elseif aabb_y(self.y + self.offsety, self.height, oy, other.height) then
if velx > 0 then
resx = ox - self.width - self.offsetx
self.touching_left = true
else
resx = ox + other.width - self.offsetx
self.touching_right = true
end
self.touching_horizontally = true
end
end
end
end
end
if self.touching_horizontally then
velx = 0
end
if self.touching_vertically then
vely = 0
end
if self.touching_horizontally or self.touching_vertically then
break
end
end
self.x = resx
self.y = resy
return velx, vely
end
function phys.Box:draw()
local x, y, w, h = self:get_rect()
love.graphics.rectangle("line", x, y, w, h)
end
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