object oriented programming doodling

oop1.p8

@@ -0,0 +1,201 @@
+pico-8 cartridge // http://www.pico-8.com
+version 27
+__lua__
+-- trying out oop
+-- by apa64
+
+-- consts
+b = {
+  left  = 0, -- ⬅️
+  right = 1, -- ➡️
+  up    = 2, -- ⬆️
+  down  = 3, -- ⬇️
+  fire1 = 4, -- 🅾️
+  fire2 = 5  -- ❎
+}
+c = {
+  black         = 0,
+  dark_blue     = 1,
+  dark_purple   = 2,
+  dark_green    = 3,
+  brown         = 4,
+  dark_gray     = 5,
+  light_gray    = 6,
+  white         = 7,
+  red           = 8,
+  orange        = 9,
+  yellow        = 10,
+  green         = 11,
+  blue          = 12,
+  indigo        = 13,
+  pink          = 14,
+  peach         = 15
+}
+
+local pixels = {}
+
+function _init()
+  add(pixels, pixel:new({ vx = 0.3 }))
+  add(pixels, controlpixel:new({ x = 63, y = 63, color = c.red }))
+  splash1 = splash:new(
+    {
+       x = 23, y = 23, w = 80, h = 80,
+       color = c.dark_gray, text_color = c.orange,
+       text = "press x to start!",
+       game_start_function = "todo give game start point here!"
+    }
+  )
+end
+
+-- this is kind of game_update(), we need splash_update() for splash state
+function _update()
+  -- do thing for each element in pixels
+  foreach(pixels,
+    function(self)
+      self:update()
+    end
+  )
+end
+
+--[[
+function splash_draw()
+  cls()
+  splash1:draw()
+end
+--]]
+function _draw()
+  cls()
+  splash1:draw()
+  -- same kind of thing as in update but with for and all
+  for p in all(pixels) do
+    p:draw()
+  end
+end
+
+-->8
+-- ###################### entity
+
+-- generic prototype object, kind of a class
+_entity = {
+  -- member vars with default values
+  x = 0, -- left x
+  y = 0, -- top y
+  w = 0, -- width
+  h = 0  -- height
+}
+
+-- the constructor creates a new object
+-- params: o is an initializer table
+-- https://www.lexaloffle.com/bbs/?pid=21527#p
+-- inheritance: https://www.lua.org/pil/16.2.html
+function _entity:new(o)
+  local o = o or {} -- use initializer or create a new object if not provided
+  -- a table may have an associated table called metatable (mt). the fields of the metatable are used to look up if key is not in this table.
+  setmetatable(o, self)
+  -- __index indicates which table is accessed when a key is not found in this. in pixel:new() call self == pixel (prototype)
+  self.__index = self
+  return o
+end
+
+-- checks collision with another entity with x,y,w,h
+function _entity:collide(other)
+  return other.x < self.x + self.w
+    and self.x < other.x + other.w
+    and other.y < self.y + self.h
+    and self.y < other.y + other.h
+end
+
+-->8
+-- ####################### pixel
+
+-- prototype: pixel, inherited from entity
+pixel = _entity:new(
+  {
+    w = 1,  -- width
+    h = 1,  -- height
+    vx = 0, -- speed x
+    vy = 0, -- speed y
+    color = c.white
+    -- more: width, height, sprite, vmax, dvmax, friction/gravity...
+  }
+)
+
+-- draws the object
+function pixel:draw()
+  pset(self.x, self.y, self.color)
+end
+
+-- updates the object
+function pixel:update()
+  self:move()
+  -- check collisions
+  -- interact with env
+end
+
+-- calculates new position based on speed, wrap around screen
+function pixel:move()
+  self.x = (self.x + self.vx) % 128
+  self.y = (self.y + self.vy) % 128
+end
+
+-- prototype: controllable pixel, inherit from pixel
+controlpixel = pixel:new(
+  {
+    dv = 0.1, -- speed change per keypress
+    vmax = 1, -- max speed
+    friction = 0.96 -- 0.01 -- slow down per update
+  }
+)
+
+-- updates the object
+function controlpixel:update()
+  -- todo check collisions
+  -- todo interact with env
+  self:input()
+  self:move()
+  -- slow down, bug: does not go quite to zero
+  --[[
+  if (self.vx != 0) self.vx = sgn(self.vx) * (abs(self.vx) - self.friction)
+  if (self.vy != 0) self.vy = sgn(self.vy) * (abs(self.vy) - self.friction)
+  -- ]]
+  self.vx *= self.friction
+  self.vy *= self.friction
+end
+
+-- handles button presses
+function controlpixel:input()
+  if (btn(b.left) and abs(self.vx) < self.vmax)  self.vx -= self.dv
+  if (btn(b.right) and abs(self.vx) < self.vmax) self.vx += self.dv
+  if (btn(b.up) and abs(self.vy) < self.vmax)    self.vy -= self.dv
+  if (btn(b.down) and abs(self.vy) < self.vmax)  self.vy += self.dv
+end
+
+-->8
+-- ###################### splash
+
+-- splash screen prototype
+splash = _entity:new(
+  {
+    text = nil,
+    color = c.light_gray,
+    text_color = c.black
+  }
+)
+
+-- todo handle input to go to next state
+function splash:update()
+  -- if (btnp(b.fire2)) game_start()
+end
+
+function splash:draw()
+  rectfill(self.x, self.y, self.x + self.w, self.y + self.h, self.color)
+  print(self.text, 63 - flr((#self.text - 1) * 4 / 2), 60, self.text_color)
+end
+
+__gfx__
+00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00700700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00077000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00077000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00700700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000