Getting a error with my draw code.

[FoundationIDE]

Code: Select all

BlockSize = 128
Map_Width = 8
Map_Height = 6

sample_map = {
	{1,0,0,0,0,0,0,0},
	{0,0,0,0,0,0,0,0},
	{0,0,0,0,0,0,0,0},
	{0,0,0,0,0,0,0,0},
	{0,0,0,0,0,0,0,0},
	{0,0,0,0,0,0,0,0},
}

LoadedMatrix = {}

function DrawBlock(GridPosX,GridPosY, block)
	love.graphics.draw(block, GridPosX * BlockSize, GridPosY * BlockSize)
end

function DrawRow(row, map_matrix)
	for CurrentColumn = 0, Map_Width, 1 do
		BlockData = map_matrix[row][CurrentColumn]
		DrawBlock(CurrentColumn, row, love.graphics.newImage("assets/" .. BlockData .. ".png"))
	end
end

function DrawMap()
	LoadedMatrix = sample_map
	for CurrentRow = 0, Map_Height, 1 do
		DrawRow(CurrentRow, LoadedMatrix)
	end
end

i get the following error: draw.lua:30: attempt to index field '?' (a nil value)

if i change line 30 to the following:

Code: Select all

BlockData = map_matrix[1][1]

it works fine with it just drawing the first value of the first row.

can somebody tell me what i'm doing wrong here?

[chezrom]

In lua, by default, the first index of index elements in table is 1 not 0, so the row of your matrix go from 1 to 6, the column from 1 to 8
You try to access element 0 that does not exist

Some advice :

• You can use #myTable to have the number of indexed elements in table.
• please in future, give the code that match the line number
• each time you want to draw a tile you load the image ? load all your image once, and reuse the loaded image.

[FoundationIDE]

In lua, by default, the first index of index elements in table is 1 not 0, so the row of your matrix go from 1 to 6, the column from 1 to 8
You try to access element 0 that does not exist

Some advice :

• You can use #myTable to have the number of indexed elements in table.
• please in future, give the code that match the line number
• each time you want to draw a tile you load the image ? load all your image once, and reuse the loaded image.

Thanks. I had the engine load all the images temporarily while I was making the drawing code. Its fixed now.

[davisdude]

Also, note that you put a comma at the end of the tile table.

sample_map = {
{1,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0},
}

That may also be causing the problem, or it may have just been a mis-type.

[Robin]

Also, note that you put a comma at the end of the tile table.

No, that's okay. Commas are allowed after the final item, to make it easier to generate Lua code.

[davisdude]

I never realized that! Thanks for that piece of information.

[Jasoco]

Also, note that you put a comma at the end of the tile table.

No, that's okay. Commas are allowed after the final item, to make it easier to generate Lua code.

You're darn right it does. You don't know how many times I pull my hair out when working with other languages that scream bloody murder if I leave an extra comma at the end. Especially when changing settings in Sublime Text's horribly outdated GUI-less preferences file structure. (Seriously, it's 2013. Give me a goddamned GUI!)