I have never done a grid based game. Can anyone help?

mykyl66 · February 2012

I can lay down a grid no issue and have a character move around a grid no issue. I can remove an object on the grid by touching it no issue.

The problem due to having no knowledge at all of grid based games is this.

Lets say I had a 5x5 grid with a character right in the center. I want to limit his moves to forward or backwards left or right to no more or less than 2 places. How would I go about this?

In my head I can imagine a table with all of the grid squares in it and capture the grid square that my character is on to compare between them but have brain ache working it out. No idea if that is even on the right path.

All part of my trying to get fully back into coding mode and trying things I have never done before.

Cheers

Mike

H4ch1 · February 2012

Umh. Not sure if I got what you mean, but basically as you said you should compare the tile where your player is to the tile that "should" be the destination. If it's a no good tile, than you don't move the player, else you do.
If the problem is knowing on which tile your player is, given for example that you have a 5x5 grid made of 32x32 pixel tiles, which top left corner is at 0, 0 position you can do:
xPosInGrid = math.ceil(player.x/32);
yPosInGrid = math.ceil(player.y/32);

Then you can use the same logic to check in which grid would happen to be the new position.
newXPosInGrid = math.ceil(newPos.x/32);
newYPosInGrid = math.ceil(newPos.y/32);

and then you compare those:
if math.abs(xPosInGrid-newXPosInGrid) <= 2 and yPosInGrid == newYPosInGrid then
move
elseif math.abs(yPosInGrid-newYPosInGrid) <= 2 and xPosInGrid == newXPosInGrid then
move
end

The yPosInGrid == newYPosInGrid and xPosInGrid == newXPosInGrid is to make sure that the player can't move in diagonal, but only left, right, down, up.

Hope this helps, let me know if I missed something (:

Caroline · February 2012

Do you mean something like this:

maxGridRows = 5		
maxGridColumns = 5
 
currentPosition = {x=3, y=3}
 
limit = 2 -- this is how far away the valid squares are
areDiagonalsAllowed = true
 
--print valid positions
 
if areDiagonalsAllowed==true then
 
	for column = currentPosition.x-limit, currentPosition.x+limit do
		for row = currentPosition.y-limit, currentPosition.y+limit do
			if column == currentPosition.x and row == currentPosition.y then
				--is current position
				print("current Position")
			else
				if row > 0 and row <= maxGridRows then
					if column > 0 and column <= maxGridColumns  then
						--is in limits
						print("column:", column, "row:", row)
					end
				end	
			end
		end
	end
 
--without diagonals
else
	for column = currentPosition.x-limit, currentPosition.x+limit do
		if column==currentPosition.x then
			--is currentPosition
			print("currentPosition")
		else
			if column > 0 and column <= maxGridColumns  then
				print("column:", column, "row:", currentPosition.y)
			end
		end
	end
 
	for row = currentPosition.y-limit, currentPosition.y+limit do
		if row==currentPosition.y then
			--is currentPosition
			print("currentPosition")
		else
			if row > 0 and row <= maxGridRows then
				print("column:", currentPosition.x, "row:", row)
			end
		end
	end
end

If you know Flash, there's an article here:
http://www.yarrcade.com/2010/04/05/grid-based-games-part-1-the-basic-grid/

And another one here:
http://archive.gamedev.net/archive/reference/programming/features/arttilebase/

Caroline · February 2012

Lol - if I can find a way to do something without more complicated maths than plus and minusses, I will

.

mykyl66 · February 2012

Thanks folks. Sorry for the delay in getting back. That clarifies a few things and gives me some ideas to play with.

Cheers

Mike

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