# Basic vector math addition
**URL:** https://discussions.unity.com/t/basic-vector-math-addition/19544
**Category:** Questions & Answers
**Created:** [April 22, 2011, 8:12pm UTC](https://discussions.unity.com/t/basic-vector-math-addition/19544 "2011-04-22T20:12:00Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@system](https://discussions.unity.com/u/system)
#### Post date: [April 22, 2011, 8:12pm UTC](https://discussions.unity.com/t/basic-vector-math-addition/19544/1 "2011-04-22T20:12:00Z")
I feel like I should know this because we went over it in calculus 3 but Im having hardest time getting my vector math to work.
Basically I need to draw a box in the editor based off of this information
```auto
public int boundaryLength = 10;
public int boundaryWidth = 10;
public GameObject boundaryStart; // where to start drawing from
```
I then try to draw the box with the following code
```auto
void OnDrawGizmos ()
{
//draw a greenbox around the boundary area
if(visualizeGrid == true)
{
//draw a a green boundary box
Vector3 point_1 = boundaryStart.transform.position;
Vector3 point_2 = new Vector3(boundaryStart.transform.position.x + boundaryLength,0,0);
Vector3 point_3 = new Vector3(boundaryStart.transform.position.x + boundaryLength, 0, boundaryStart.transform.position.z + boundaryWidth);
Vector3 point_4 = new Vector3(0, 0, boundaryStart.transform.position.z + boundaryWidth);
Gizmos.color = Color.green;
Gizmos.DrawLine(point_1, point_2);
Gizmos.DrawLine(point_2, point_3);
Gizmos.DrawLine(point_3, point_4);
Gizmos.DrawLine(point_4, point_1);
}
else
{
return; //if visualize gride is turned of, exit function
}
}
```
This to me seems like it should draw, but I get this weird quadrilateral that is a half box half...not box
Maby my math is wrong but i cant seem to see where
---
### Author:  [@DaveA](https://discussions.unity.com/u/DaveA)
#### Post date: [April 22, 2011, 8:20pm UTC](https://discussions.unity.com/t/basic-vector-math-addition/19544/2 "2011-04-22T20:20:18Z")
Vector3 point\_4 = new Vector3(0, 0, boundaryStart.transform.position.z + boundaryWidth);
Your x,y for this is always zero. transform.position is in world coords. I think you want some thing more like:
Vector3 point\_4 = new Vector3(boundaryStart.transform.position.x, 0, boundaryStart.transform.position.z + boundaryWidth);
In other words, your 'local origin' will be transform.position.x and z, and the offsets will be position.x + length and .z + width.