snake prototype

debugoverlay.lua

overlay = {}

local fps = 0

function overlay.draw()
  love.graphics.print('FPS: ' .. fps, 25, 25)
end

function overlay.update(dt)
  fps = 1 / dt - (1 / dt % 1)
end

return overlay

main.lua

local vector2 = require "vector2"
local dbgoverlay = require "debugoverlay"

local score = 0
local segmentSize = 32
local speed = 5
local currentDirection = vector2.new(1, 0)

segment = {}
function segment.new(parent, position, direction)
  local self = {}
  if not parent then
    self.position = position
    self.direction = direction
  else
    parent.child = self
    self.position = parent.position - parent.direction
    self.direction = parent.direction
  end

  function self:changeDirection(direction)
    if self.child then
      self.child:changeDirection(self.direction)
    end
    --avoid turning back on itself
    if self.direction * -1 ~= direction then
      self.direction = direction
    end
    --alignment correction (irregular dts might cause the segments to be unaligned)
    if self.child then
      self.child.position = self.position - self.child.direction
    end
  end

  function self:addSegment()
    if self.child then self.child:addSegment(); return end
    self.child = segment.new(self)
  end

  function self:update(dt)
    if self.child then
      self.child:update(dt)
    end
    self.position = self.position + self.direction * dt * speed
  end

  return self
end

head = segment.new(nil, vector2.new(5, 5), vector2.new(1, 0))
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()
head:addSegment()

function love.load()
end

function love.draw()
  --draw head
  love.graphics.setColor(255, 0, 0)
  love.graphics.rectangle('fill', head.position.x * segmentSize, head.position.y * segmentSize, segmentSize, segmentSize)
  love.graphics.setColor(255, 255, 255)
  --draw segments
  local currentSegment = head
  while currentSegment.child do
    love.graphics.rectangle('fill', currentSegment.child.position.x * segmentSize + 0.5, currentSegment.child.position.y * segmentSize + 0.5, segmentSize - 2, segmentSize - 2)
    currentSegment = currentSegment.child
  end

  dbgoverlay.draw()
end

function love.keypressed(key)
    if key == 'left' then
      currentDirection = vector2.new(-1, 0)
    end
    if key == 'right' then
      currentDirection = vector2.new(1, 0)
    end
    if key == 'up' then
      currentDirection = vector2.new(0, -1)
    end
    if key == 'down' then
      currentDirection = vector2.new(0, 1)
    end
end


local timer = 1 / speed

function love.update(dt)
  dbgoverlay.update(dt)

  timer = timer - dt
  if timer <= 0 then
    timer = 1 / speed
    head:changeDirection(currentDirection)
  end
  head:update(dt)
end

vector2.lua

--[[
Copyright (c) 2015, Westerbly (radgeRayden) Snaydley
This is licensed under the MIT license (http://opensource.org/licenses/MIT).
Time of creation: June 30th, 2015 12:32 GMT
Description:
Helper script for handling of Vector2 type objects.
--]]

local vector2 = {}

function vector2.new(x, y)
  local self = {}
  setmetatable(self, vector2.meta)
  self.x = x
  self.y = y
  function self:magnitude()
    local x = math.abs(self.x)
    local y = math.abs(self.y)
    return math.sqrt(x ^ 2 + y ^ 2)
  end

  function self:normalized()
    local magnitude = self:magnitude()
    return vector2.new(self.x / magnitude, self.y / magnitude)
  end

  return self
end

function vector2.add(v1, v2)
  return vector2.new(v1.x + v2.x, v1.y + v2.y)
end

function vector2.sub(v1, v2)
  return vector2.new(v1.x - v2.x, v1.y - v2.y)
end

function vector2.multbynumber(v, number)
  if type(number) == "number" then
    return vector2.new(v.x * number, v.y * number)
  else
    error("Tried to multiply a vector but the other operand wasn't a number.")
  end
end

function vector2.divbynumber(v, number)
  if type(number) == "number" then
    return vector2.new(v.x / number, v.y / number)
  else
    error("Tried to divide a vector but the other operand wasn't a number.")
  end
end

function vector2.compare(v1, v2)
  return v1.x == v2.x and v1.y == v2.y
end

function vector2.distance(v1, v2)
  return (v2 - v1):magnitude()
end

function vector2.tostring(v)
  return "vector2(" .. v.x .. ", " .. v.y ..")"
end

function vector2.zero()
  return vector2.new(0, 0)
end

function vector2.one()
  return vector2.new(1, 1)
end

vector2.meta = {}
vector2.meta.__add = vector2.add
vector2.meta.__sub = vector2.sub
vector2.meta.__mul = vector2.multbynumber
vector2.meta.__div = vector2.divbynumber
vector2.meta.__eq = vector2.compare
vector2.meta.__tostring = vector2.tostring

return vector2