2 replies to this topic

[wilcomega]

intro:
hello everybody,

today i am gonna be teaching you guys how to make a topDown Game with OOP!
now if you dont know what OOP is then you should have a look at this topic:
http://www.computercraft.info/forums2/index.php?/topic/984-advancedsnippetsmetatables-metamethods/

basic setup:
for this game we are gonna use a metatable, in this table we are gonna put some usefull stuff for later on like the health, position, sprite that kind of stuff
using this method lets us use only ONE function for example the movement of multiple objects or one function to draw all the objects

lets get coding:
Config:

first of all we want to make the config it look something like this:

args = { ... }

-- config
running = true
debug = false
local w, h = term.getSize() w = math.floor(w) h = math.floor(h)
object = {}
objectCount = 0
label = {}
labelCount = 0
ticks = 0

what this does is it creates the needed variables for later on
a object is the main thing it can be the player and it can be a wall(later on)

Classes:

if you dont know what a class is click the link in the top of this post
a class:

local Object = {}
Object.default = {eType = "Living", name = "", strenght = 1, speed = 1, AI = {}, sprite = {"", "", "", ""}, static = true, visible = true, dir = 4, x = 1, y = 1}
Object.mt = {__index = Object.default}
function Object:new(t)
		setmetatable(t, Object.mt)
		object[objectCount] = t
		objectCount = objectCount + 1
		return t
end

line by line explanation:
1. we create a new array or list or whatever
2. in that array we put another array called default this will be the value of all the copy's
3. we prepare a metatable
4. a new function with a argument as table
5. it sets the metatable
6. it registers the new object in the array or list that we made in the config
7. it counts up to prevent overriding
8. it returns the modified table
9. the function ends

BTW: we are gonna use this class, these are the classes in total:

local Object = {}
Object.default = {eType = "Living", name = "", strenght = 1, speed = 1, AI = {}, sprite = {"", "", "", ""}, dir = 4, x = 1, y = 1}
Object.mt = {__index = Object.default}
function Object:new(t)
		setmetatable(t, Object.mt)
		object[objectCount] = t
		objectCount = objectCount + 1
		return t
end

local Label = {}
Label.default = {name = "", text = "", visible = true, x = 1, y = 1}
Label.mt = {__index = Label.default}
function Label:new(t)
		setmetatable(t, Label.mt)
		label[labelCount] = t
		labelCount = labelCount + 1
		return t
end

Game functions:
here we are gonna put the functions like move and checkPos and checkPosMove

first of all i like to make a function that draws everything:

function draw()
  for i = 0,#object do
	if object[i].visible == true then
	  term.setCursorPos(object[i].x, object[i].y)
	  term.write(object[i].sprite[object.dir])
	end
  end
  for i = 0,#label do
	if label[i].visible == true then
	  term.setCursorPos(label[i].x, label[i].y)
	  term.write(label[i].text)
	end
  end
end

explanation:

Spoiler

the first 'for loop' draws all the objects
in that loop it checks if the object is visible
then it draws the sprite depending on the objects direction

then it does the same with the labels but without the direction

next up i made the checkPosMove function

function checkPosMove( obj, dir )
if dir == 1 then
  for i = 0,#object do
   if object[i].static == true and object[i].x == obj.x - 1 and object[i].y == obj.y then
	return object[i]
   end
  end
end
if dir == 2 then
  for i = 0,#object do
   if object[i].static == true and object[i].x == obj.x and object[i].y == obj.y - 1 then
	return object[i]
   end
  end
end
if dir == 3 then
  for i = 0,#object do
   if object[i].static == true and object[i].x == obj.x + 1 and object[i].y == obj.y then
	return object[i]
   end
  end
end
if dir == 4 then
  for i = 0,#object do
   if object[i].static == true and object[i].x == obj.x and object[i].y == obj.y + 1 then
	return object[i]
   end
  end
end

return false
end

explanation:

Spoiler

lets take a look at ONE of the directions
it takes a look at all of the objects and check their position if its in the way then it returns the object thats in the way

thx for being here

wilcomega

btw: please leave a comment with what you think

[tommyroyall]

Hey man, nice job />. Can't wait for the second part.

[wilcomega]

i am working on the second part right now />