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SgtReckless

Cart #fehugubisi-0 | 2020-07-02 | Code ▽ | Embed ▽ | License: CC4-BY-NC-SA

I'm trying to make a checkers game as a first game, and have the function loc_type(loc) which should return 1 if the location has a black piece and a 2 if the location has a white piece, and zero if it's empty.

This works perfectly well for setting up the board but I'm now trying to code selecting a piece. But when I call loc_type, it seems to think that pos = {5,7} (Which is the last white piece I spawn).

I'm really unsure how to fix this. Any thoughts?

Code for reference

 
--game logic

function _init()
    -- enable mouse
    poke(0x5f2d, 1)
    curr_peice = nil
    val = {-1,-1}
    -- starting places for peices (might want to automate this?)
    blacks = {{0,0},{0,2},{0,4},{0,6},{1,1},{1,3},{1,5},{1,7},{2,0},{2,2},{2,4},{2,6}}
    whites = {{7,1},{7,3},{7,5},{7,7},{6,0},{6,2},{6,4},{6,6},{5,1},{5,3},{5,5},{5,7}}

end

function _draw()

    --clear screen
    cls(0)
    -- draw board and peices
    draw_board()
    draw_peices()
    -- draw cursor
    spr(9,curr_x*16,curr_y*16,2,2)
    print(val,3)
    if curr_peice != nil then
        spr(9,curr_peice[1]*16,curr_peice[2]*16,2,2)
    end
end

function _update()
    -- calculate current square
    curr_x = mid(0,stat(32)\16,7)
    curr_y = mid(0,stat(33)\16,7)

    val = loc_type({curr_x,curr_y})
end

-- graphics

function draw_board()

    for i=0,7 do
        for j=0,7 do

            -- checks if square is black
        is_black =  ((i+j)%2)
        rectfill(i*16,j*16,(i+1)*16-1,(j+1)*16-1,is_black*7)

        end
    end

end

function draw_single(single)

    piece_type = loc_type(single)

    -- draws the peice
    if piece_type == 1 then
        spr(1,single[1]*16,single[2]*16,2,2)
    elseif piece_type == 2 then
        spr(3,single[1]*16,single[2]*16,2,2)
    else
        print("error: no peice here")
    end

end

function draw_peices()
    foreach(blacks,draw_single) 
    foreach(whites,draw_single)
end

-- utility functions

function loc_type(loc)

    is_black = object_in_table(loc,blacks)
    is_white = object_in_table(loc,whites)
    if is_black and is_white then
        print("error: two peices in the same place")
        return -1
    end

    if is_black then
        return 1
    elseif is_white then
        return 2
    else
        return 0
    end

end

function object_in_table(obj,t)
    for t_obj in all(t) do
        if t_obj == obj then
            return true
        end
    end

    return false
end
P#78789 2020-07-02 13:59 ( Edited 2020-07-02 14:02)


remcode
remcode

I am unclear what you mean regarding "But when I call loc_type, it seems to think that pos = {5,7} (Which is the last white piece I spawn)."

That aside:

"Lua compares tables, userdata, and functions by reference, that is, two such values are considered equal only if they are the very same object." Source: https://www.lua.org/pil/3.2.html

So two tables with the same values in are not the same table (unless they are also the same object).

In object_in_table change the check for equality from if t_obj == obj then to:

 
  if t_obj[1]==obj[1] and t_obj[2]==obj[2] then

Does that fix the bug, or could you explain it further?

P#78793 2020-07-02 14:49

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