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I didn't know which forum section to post this in and so i just decided this because i have dbp. Anyways, I am having trouble making a simple grid. A grid in which if you put your mouse in just one pixel of one of the boxes, it snaps to it. Ive looked through the forums on 2D grids and nothing really met what I was having a problem with.

Hi,

If you're looking to make a normal rectangular grid, then you can use the following expressions:

If each grid cell has a size of (cWidth, cHeight) and the grids origin is located at coordinates (GridX, GridY), then:

Finding the grid coordinates from 2D coordinates:
GridPosX# = (PosX# - GridX) / cWidth
GridPosY# = (PosY# - GridY) / cHeight

Finding 2D coordinates from grid coordinates:
PosX# = GridPosX# * cWidth + GridX
PosY# = GridPosY# * cHeight + GridY

'Snapping' grid coordinates:
(You basically have to round them up/down, for example)
GridPosX = int(GridPosX# + 0.5)
GridPosY = int(GridPosY# + 0.5)
-> Gives more or less unwanted results when GridPosX/Y# < 0.0 though, you might want to write your own rounding function.

'Snapping' 2D coordinates:
GridPosX# = (PosX# - GridX) / cWidth
GridPosY# = (PosY# - GridY) / cHeight
GridPosX = int(GridPosX# + 0.5)
GridPosY = int(GridPosY# + 0.5)
PosX = GridPosX * cWidth + GridX
PosY = GridPosY * cHeight + GridY

I think this sums it all up. Good luck with your project ^^!

Sven B

thank you for the replay, ill try this.

Everything Sven says looks correct, although he explains in a typical coders logic. By that I mean stating code snippets without explanation. When snapping an object to a grid you just have to think logically.

If your screen estate is 100x100 pixels and you have 10x10 grid within that, all you need do is divide your pixel x and y position by 10 ( 100/10=10), to get a snap influence.
Lets say you click pixel 11x11. Dividing that by ten would equal 1.1 x 1.1, rounding that down you get 1x1, which would bet correct and snap you to the grid If you click pixel 9x9 you would get .9x.9, which would be rounded down to 0 x 0.
I'm pretty sure DB will automatically do this if you set your variables as an integer, rather than a float. If you want to control it use the int() command, which will automatically round your numbers down. You can also round up if you use the ceil command, rather than int. But it is not needed for this, just giving you a little info

thanks, thats more than i knew before