1 files changed, 208 insertions, 0 deletions
diff --git a/entity.lua b/entity.lua
new file mode 100644
index 0000000..dfad84f
--- /dev/null
+++ b/entity.lua
@@ -0,0 +1,208 @@
+Entities = {
+    Player = 0,
+    Sword = 1,
+    Enemy = 2
+}
+States = {
+    Walk = "walk",
+    Idle = "idle"
+}
+
+
+_id = 0
+function _next_id()
+    i = _id
+    _id += 1
+    return i
+end
+
+Entity = {}
+Entity.__index = Entity
+function Entity:b_add_state(name, state)
+    if self.states == nil then self.states = {} end
+    self.states[name] = state
+    if self.state == nil then self.state = name end
+    return self
+end
+function Entity:b_state(name)
+    assert(self.states[name] != nil)
+    self.state = name
+    return self
+end
+function Entity:b_render_order(ord)
+    self.render_order = ord
+    return self
+end
+function Entity:b_position(vec)
+    self.position = vec2(vec)
+    return self
+end
+function Entity:b_sprite_position(vec)
+    self.sprite_position = vec2(vec)
+    return self
+end
+function Entity:b_type(entity_type)
+    self.entity_type = type
+    return self
+end
+function Entity:b_equipped(equipped)
+    self.equipped = equipped
+    return self
+end
+function Entity:b_collidable()
+    self.collision = true
+    return self
+end
+
+function Entity:transition_to(state_name)
+    if self:transition(self.state, state_name) then
+        self.state = state_name
+        self.state_stopwatch = 0
+    end
+    return self
+end
+
+function Entity:transition(from, to)
+    if from == States.Walk and to == States.Idle or to == States.Idle and from == States.Walk then
+        return true
+    end
+    return false
+end
+
+function Entity:update(dt)
+    if self.state_stopwatch == nil then
+        self.state_stopwatch = 0
+    end
+    self.state_stopwatch += dt
+    self:integrate(dt)
+
+    self:update_sprite_position()
+    self:update_line_of_sight()
+
+    if (self.velocity.x == 0 and self.velocity.x == self.velocity.y) then
+        self:transition_to(States.Idle)
+    else
+        self:transition_to(States.Walk)
+    end
+
+    if (self.equipped != nil) then
+        parent = self
+        foreach(self.equipped, function (e) e:equipped_from(parent) end)
+    end
+end
+
+function Entity:update_line_of_sight()
+    nv = self.velocity:apply(normalize_scalar)
+    if nv.y != 0 then self.line_of_sight = vec2(0, nv.y)
+    elseif nv.x != 0 then self.line_of_sight = vec2(nv.x, 0) 
+    else self.line_of_sight = vec2(0, 0) end
+end
+
+-- prevent cobblestoning during non-manhattan movement by "lagging" the sprite
+-- behind the actual physical position
+function Entity:update_sprite_position()
+    if self.sprite_position == nil then return end
+
+    -- step in only x or y. trivial
+    if self.velocity == nil or self.velocity.y == 0 or self.velocity.x == 0 then
+        self.sprite_position.x = self.position.x
+        self.sprite_position.y = self.position.y
+        return
+    end
+
+    dpos = self.position - self.sprite_position
+    dx, dy = dpos.x, dpos.y
+    adx, ady = abs(dx), abs(dy)
+
+    yslow = abs(self.velocity.y) < abs(self.velocity.x)
+    xslow = abs(self.velocity.x) <= abs(self.velocity.y)
+
+    pushx, pushy = false, false
+    jerkdelta = 1
+    if adx >= jerkdelta and xslow and ady >= 1 then
+        pushx, pushy = true, true
+    elseif ady >= jerkdelta and yslow and adx >= 1 then
+        pushx, pushy = true, true
+    elseif xslow and ady >= 1 then
+        pushy = true
+    elseif yslow and adx >= 1 then
+        pushx = true
+    end
+
+    if pushx then
+        func = flr
+        if dx < 0 then func = ceil end
+        self.sprite_position.x += func(dx)
+    end
+    if pushy then
+        func = flr
+        if dy < 0 then func = ceil end
+        self.sprite_position.y += func(dy)
+    end
+
+    return self
+end
+
+function Entity:integrate(dt)
+    if (self.velocity != nil) then
+        self.position = self.position + (self.velocity * dt)
+    end
+end
+
+_equip_distance = 6
+function Entity:equipped_from(parent)
+    self.line_of_sight = vec2(parent.line_of_sight)
+
+    offset = (parent.line_of_sight * _equip_distance)
+
+    self.position = parent.position + offset
+    self.sprite_position = parent.sprite_position + offset
+end
+
+function _get_frame(anim, t)
+    len = #anim.seq
+    frames_passed = (t / anim.dt)
+    idx = flr(1 + (frames_passed % len))
+    return anim.seq[idx]
+end
+
+_animation_keys = {"neg", "", "pos"}
+function _get_animation_key(line_of_sight)
+    n_line_of_sight = line_of_sight:apply(normalize_scalar)
+    if n_line_of_sight.y ~= 0 then
+        return _animation_keys[n_line_of_sight.y + 2] .. "_y"
+    end
+    return _animation_keys[n_line_of_sight.x + 2] .. "_x"
+end
+
+function Entity:render()
+    pos = self.sprite_position or self.position
+
+    animation = self.states[self.state].animation
+    if (animation == nil) then return end
+    key = _get_animation_key(self.line_of_sight)
+    animation = animation[key] or animation
+    assert(animation[key])
+
+    frame = _get_frame(animation.sequence, self.state_t)
+    reflection = animation.reflection or vec2(false, false)
+    spr(
+        frame,
+        entity.sprite_position.x, entity.sprite_position.y,
+        1, 1,
+        reflection.x, reflection.y
+    )
+end
+
+function entity()
+    id = _next_id()
+    World.add(setmetatable(
+        {
+            id = id,
+            position = vec2(0,0),
+            velocity = vec2(0,0),
+            collision = false
+        }, Entity
+    ))
+    return World[id]
+end