Snap object to grid

Questions & Answers
1

hi guys.

i’ve made a grid by creating a plane and set grid texture on it,besides I had a script for drag-and-drop object.

Now, i trying to create a script that when i release the mouse, the object i’ve been dragging snaps to the line of grid (in the picture shown below, the red is object). Can anyone help me? thanks in advance !

alt text

//Drag-and-Drop script

using UnityEngine;

using System.Collections;

public class MovePoint2 : MonoBehaviour
{
	private Vector3 screenPoint;
	private Vector3 offset;

	void OnMouseDown() 
	{ 
		screenPoint = Camera.main.WorldToScreenPoint(gameObject.transform.position);
		
		offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z));
		
		Screen.showCursor = false;
		

	}
	
	void OnMouseDrag() 
	{ 
		Vector3 curScreenPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);
		
		Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint) + offset;
		
		transform.position = curPosition;
		
	}
	
	void OnMouseUp()
	{
		Screen.showCursor = true;
	}
}
2

Here’s a function you just need to call to snap to your grid object.
The grid width/height is determined from the material’s tiling, (my texture is just an edge, then repeated to make a grid)

Then we manipulate the position relative to the grid (a quad in my case) so it’s irrelevant how much it’s scaled, and even works when rotated!

26021-snaptogrid_rot.gif

Vector3 SnapToGrid(Vector3 Position)
	{
		GameObject grid = GameObject.Find ("grid");
		if (! grid)
			return Position;

		//	get grid size from the texture tiling
		Vector2 GridSize = grid.renderer.material.mainTextureScale;

		//	get position on the quad from -0.5...0.5 (regardless of scale)
		Vector3 gridPosition = grid.transform.InverseTransformPoint( Position );
		//	scale up to a number on the grid, round the number to a whole number, then put back to local size
		gridPosition.x = Mathf.Round( gridPosition.x * GridSize.x ) / GridSize.x;
		gridPosition.y = Mathf.Round( gridPosition.y * GridSize.y ) / GridSize.y;

		//	don't go out of bounds
		gridPosition.x = Mathf.Min ( 0.5f, Mathf.Max (-0.5f, gridPosition.x) );
		gridPosition.y = Mathf.Min ( 0.5f, Mathf.Max (-0.5f, gridPosition.y) );

		Position = grid.transform.TransformPoint( gridPosition );
		return Position;
	}

Then change OnMouseDrag to include this to snap-as-you-drag

transform.position = SnapToGrid(curPosition);

or when you let go, in OnMouseUp…

transform.position = SnapToGrid(transform.position);

My example is just a square, but you just need to change the square so the center is the top of your line, or make a small adjustment to the final Postion = line

[26022-snaptogrid699158.zip|26022]