using UnityEngine;

 using System.Collections;

 using System.Collections.Generic;

 [ExecuteInEditMode]

 public class Parabola : MonoBehaviour {

     //重力

     [Range(,)]

     public float gravity = 0.13f;

     //最大长度

     public float maxLength = ;

     //两点之间的距离

     const float length = 0.2f;

     //点集合

     List<Vector3> m_List = new List<Vector3>();

     Material m_LineMat;

     public void OnRenderObject() {

         CreateLineMaterial();

         m_LineMat.SetPass();

         Vector3 position = transform.position;

         Vector3 forward = transform.rotation * Vector3.forward * length;

         Vector3 newPos = position;

         Vector3 lastPos = newPos;

         m_List.Add(newPos);

         int i = , iMax = ;

         float dis = ;

         while (dis < maxLength) {

             i++;

             newPos = lastPos + forward + Vector3.up * i * -gravity * 0.1f;

             dis += Vector3.Distance(lastPos, newPos);

             m_List.Add(newPos);

             lastPos = newPos;

         }

         GL.Begin(GL.LINES);

         i = ;

         iMax = m_List.Count;

         for (i = ; i < iMax; i++) {

             GL.Vertex(m_List[i]);

         }

         GL.End();

         m_List.Clear();

     }

     void CreateLineMaterial() {

         if (!m_LineMat) {

             var shader = Shader.Find("Hidden/Internal-Colored");

             m_LineMat = new Material(shader);

             m_LineMat.hideFlags = HideFlags.HideAndDontSave;

             m_LineMat.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.SrcAlpha);

             m_LineMat.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);

             m_LineMat.SetInt("_Cull", (int)UnityEngine.Rendering.CullMode.Off);

             m_LineMat.SetInt("_ZWrite", );

         }

     }

 }