snap object to grid

[mangadrive]

I have a selector that goes over a tilemap that is 64x64. I have it snapping to tiles if an enemy is present, but for the life of my can't seem to create a free targeting option that would just allow me to select the blank tile with a mouse and snap the selector to that tile.

Code: Select all

function ents.TargetLockSelected() -- Enemy Selection with Mouse locked to enemies
	for i, ent in pairs(ents.enemies) do
	
	local x = love.mouse.getX()
	local y = love.mouse.getY() 
	
	
	
	if x >= 272 and x <= 528 and y >= 32 and y <= 288 and x > ent.x and y > ent.y then
	selector.x = ent.x
	selector.y = ent.y
	end
	

	end
	end

I just need a solution that will point to a tile within that same range and not worry about enemies but still snap to the 64/64 grid... and I know it's easier than my mind is letting it be right now.

[Plu]

You have to round the selection ring's coodinates to something that aligns with the grid. I don't know your full code, but the basic idea is like this:

Code: Select all

x = math.floor( mouse.x / 64 ) * 64

That would snap your x to always be a multiple of 64. Depending on whether you have your x in the center or a corner of the tile, and on whether you start counting at 0 or 1, you might have to add another 32 or 64 to the total.

[mangadrive]

I knew it was something simple like this and I didn't have math.floor considered.

Thank you very much.

[mangadrive]

So just a note for anyone that may search this:

I ended up actually hard coding all the values like a GUI element for the selection pointer because while math.floor and the tile considerations do work, it's problematic on a tile map or grid that's not centered on 0. You can offset it by adding/subtracting portions of the tile width/height as suggested, but you'll get weird things like the selection jumping to the left/right/up/down if you click on the left/right/up/down half of the tile.

So in the end I wrote a bunch of if statements that considered x/y instead and would just shift the selector to the tile somewhat manually like so in this example:

Code: Select all

local x = love.mouse.getX()

if x >= 272 and x <= 336 then
selector.x = 272
end

More code, but more accurate for needed purposes.

Moral of the story: Over thinking is dangerous and you aren't going to kill your whole project and I could have fixed this myself long ago had I not been stubborn into thinking I needed to do it the "short" way v/s the more code way that actually fixed the problem.

[Germanunkol]

I know they say to never change a running system, but:
I think you should look into this further. Hard-Coding is the easiest way, but changing anything later on will be a pain.*

How are you offsetting the map? Are you using translate?

You should look into vrdl's "HUMP" library, it offers a camera that is really useful here. If you use this, there's a function that converts mouse coordinates to world-coordinates, which is probably the problem that you're having.

Although it's really weird that hard coding it fixes it. Maybe you could post a .love showing the problem?

I've got a working example of snap-to-grid in the attached demo.

Bezier.love

(Fixed version) Usage: Draw a shape using CTRL+click multiple times. Then click outside the shape and drag it. Both creating of points and dragging the shape snap to grid.

(28.13 KiB) Downloaded 228 times

The code for smapping to grid is in Scripts/shapeControl.lua, in function ShapeControl:update( mX, mY, dt ).
mX and mY are the mouse coordinates, transformed into world coordinates, after moving and scaling the camera.
Then, you can simply do:

Code: Select all

	if self.snapToGrid then
		mX = math.floor((mX+self.gridSize/2)/self.gridSize)*self.gridSize
		mY = math.floor((mY+self.gridSize/2)/self.gridSize)*self.gridSize
	end

"+self.gridSize/2" is there in ordeer to round up if mX or mY are more than half way to the next grid line.

* If you really need to hard-code it, at least do it using a while or for loop, something like:

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tileSize = 50
curX = 0
while curX < x do
	if curX + tileSize >= x then
		x = curX
		break
	end
	curX = curX + tileSize
end

(untested)

[bekey]

-snip-

[Germanunkol]

Very sorry about that, I had some linux-specific code in there (os.executed("sleep 0.1")) for debugging purposes which I forgot to replace with the correct platform-independent version (love.timer.sleep(0.1)). Thanks for pointing that out!

Updated the post above, added new version.
Could you try again and see if I fixed it?

Making a mental not to self never to use os.execute again, unless needed.

[bekey]

-snip-

[Germanunkol]

Updated again (see post above). I've never seen that error you're posting, but I suspect it has to do with giving values of 1f instead of 1.0 in a shader?

Weird that it works for me, though...

WIll boot up Windows and try it myself.
Edit: Tested the new version, works for me on Linux and on Win7, 64bit.

[bekey]

-snip-