三个点生成抛物线 ，计算组成抛物线的点

王者再临

1. using UnityEngine;
   
2. using System.Collections;
   
3. using System.Collections.Generic;
   
4. //iTween里抄来的
   
5. public class otherTest : MonoBehaviour {
   
6. 
   
7.         /// <summary>
   
8.         /// 三点计算抛物线.
   
9.         /// </summary>
   
10.         /// <returns>组成抛物线的点.</returns>
    
11.         /// <param name="path">确定抛物线的三个点或者更多的点的数组.</param>
    
12.         public static List<Vector3> DrawPathHelper(Vector3[] path){
    
13.                 List<Vector3> array = new List<Vector3>(177);
    
14.                 Vector3[] vector3s = PathControlPointGenerator(path);
    
15.                 //Line Draw:
    
16.                 Vector3 prevPt = Interp(vector3s,0);
    
17.                 int SmoothAmount = path.Length*20;
    
18.                 for (int i = 1; i <= SmoothAmount; i++)
    
19.                 {
    
20.                         float pm = (float) i / SmoothAmount;
    
21.                         Vector3 currPt = Interp(vector3s,pm);
    
22.                                 array.Add(currPt);
    
23.                         prevPt = currPt;
    
24.                 }
    
25.                 return  array;
    
26.         }
    
27.        
    
28.         private static Vector3[] PathControlPointGenerator(Vector3[] path){
    
29.                 Vector3[] suppliedPath;
    
30.                 Vector3[] vector3s;
    
31.                
    
32.                 //create and store path points:
    
33.                 suppliedPath = path;
    
34.                
    
35.                 //populate calculate path;
    
36.                 int offset = 2;
    
37.                 vector3s = new Vector3[suppliedPath.Length+offset];
    
38.                 System.Array.Copy(suppliedPath,0,vector3s,1,suppliedPath.Length);
    
39.                
    
40.                 //populate start and end control points:
    
41.                 //vector3s[0] = vector3s[1] - vector3s[2];
    
42.                 vector3s[0] = vector3s[1] + (vector3s[1] - vector3s[2]);
    
43.                 vector3s[vector3s.Length-1] = vector3s[vector3s.Length-2] + (vector3s[vector3s.Length-2] - vector3s[vector3s.Length-3]);
    
44.                
    
45.                 //is this a closed, continuous loop? yes? well then so let's make a continuous Catmull-Rom spline!
    
46.                 if(vector3s[1] == vector3s[vector3s.Length-2]){
    
47.                         Vector3[] tmpLoopspline = new Vector3[vector3s.Length];
    
48.                         System.Array.Copy(vector3s,tmpLoopSpline,vector3s.Length);
    
49.                         tmpLoopSpline[0]=tmpLoopSpline[tmpLoopSpline.Length-3];
    
50.                         tmpLoopSpline[tmpLoopSpline.Length-1]=tmpLoopSpline[2];
    
51.                         vector3s=new Vector3[tmpLoopSpline.Length];
    
52.                         System.Array.Copy(tmpLoopSpline,vector3s,tmpLoopSpline.Length);
    
53.                 }       
    
54.                
    
55.                 return(vector3s);
    
56.         }
    
57. 
    
58.         //andeeee from the Unity forum's steller Catmull-Rom class ( http://forum.unity3d.com/viewtopic.php?p=218400#218400 ):
    
59.         private static Vector3 Interp(Vector3[] pts, float t){
    
60.                 int numSections = pts.Length - 3;
    
61.                 int currPt = Mathf.Min(Mathf.FloorToInt(t * (float) numSections), numSections - 1);
    
62.                 float u = t * (float) numSections - (float) currPt;
    
63.                
    
64.                 Vector3 a = pts[currPt];
    
65.                 Vector3 b = pts[currPt + 1];
    
66.                 Vector3 c = pts[currPt + 2];
    
67.                 Vector3 d = pts[currPt + 3];
    
68.                
    
69.                 return .5f * (
    
70.                         (-a + 3f * b - 3f * c + d) * (u * u * u)
    
71.                         + (2f * a - 5f * b + 4f * c - d) * (u * u)
    
72.                         + (-a + c) * u
    
73.                         + 2f * b
    
74.                         );
    
75.         }       
    
76. }

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