鼠标拖动出现直线碰撞器

using UnityEngine;
using System.Collections;

public class DrawPhysicsLine : MonoBehaviour
{
private LineRenderer line; // Reference to LineRenderer
private Vector3 mousePos;
private Vector3 startPos;   // Start position of line
private Vector3 endPos; // End position of line

void Update()
{

// On mouse down new line will be created
if (Input.GetMouseButtonDown(0))
{
if (line == null)
createLine();
mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
mousePos.z = 0;
line.SetPosition(0, mousePos);
startPos = mousePos;
}
else if (Input.GetMouseButtonUp(0))
{
if (line)
{
mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
mousePos.z = 0;
line.SetPosition(1, mousePos);
endPos = mousePos;
addColliderToLine();
line = null;
}
}
else if (Input.GetMouseButton(0))
{
if (line)
{
mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
mousePos.z = 0;
line.SetPosition(1, mousePos);
}
}
}
// Following method creates line runtime using Line Renderer component
private void createLine()
{
line = new GameObject("Line").AddComponent<LineRenderer>();
line.material = new Material(Shader.Find("Diffuse"));
line.SetVertexCount(2);
line.SetWidth(0.1f, 0.1f);
line.SetColors(Color.black, Color.black);
line.useWorldSpace = true;
}
// Following method adds collider to created line
private void addColliderToLine()
{
BoxCollider col = new GameObject("Collider").AddComponent<BoxCollider>();
col.transform.parent = line.transform; // Collider is added as child object of line
float lineLength = Vector3.Distance(startPos, endPos); // length of line
col.size = new Vector3(lineLength, 0.1f, 1f); // size of collider is set where X is length of line, Y is width of line, Z will be set as per requirement
Vector3 midPoint = (startPos + endPos) / 2;
col.transform.position = midPoint; // setting position of collider object
// Following lines calculate the angle between startPos and endPos
float angle = (Mathf.Abs(startPos.y - endPos.y) / Mathf.Abs(startPos.x - endPos.x));
if ((startPos.y < endPos.y && startPos.x > endPos.x) || (endPos.y < startPos.y && endPos.x > startPos.x))
{
angle *= -1;
}
angle = Mathf.Rad2Deg * Mathf.Atan(angle);
col.transform.Rotate(0, 0, angle);
}
}