Help with a falling sand like game!!!

Hello, I'm working on a game style the powder toy, however I can not do the physical, can someone help me?
The code's there:

Code (JavaScript):

1. #pragma strict
2.  
3. public static var Map: Texture2D;
4. //var Map_Pixels: Pixel[];
5. //Init Test Array
6. public var Map_Pixels = new Array(Pixel);
7. //Finish Test Array
8. var Pixels: Class_Pixel;
9. var MapScale: Vector2;
10. var InsertPosition: Vector2;
11. var InsertPixel: int;
12. var Mat: Material;
13. private var iCount: int = 0;
14. private var XY: Vector2;
15. private var UseIndex: int;
16. var pos: Vector3;
17. private var fwd = transform.TransformDirection(Vector3.forward);
18. private var hit: RaycastHit;
19. var Mouse: Vector2;
20. private var ShowInventory: boolean;
21. var PhysicsDelay: float;
22.  
23. public var Pixel: Pixel;
24.  
25. //Inventory Variables In;
26. var ItensInInventory: int[];
27. private var SelectedItemInInventory: int;
28. //Inventory Variables Out;
29.  
30. function Start() {
31. var Pixel: Pixel;
32. var Position: Vector2;
33. Map = new Texture2D(MapScale.x,MapScale.y);
34. for(var i:int=0;i<Map.height;i++)
35.    for(var j:int=0;j<Map.width;j++)
36.       {
37.       //Pixel.Name = Pixels.ReturnPixelName(0);
38.       //Pixel.Pixel = Pixels.ReturnPixelColor(0);
39.       //Pixel.Reagents = Pixels.ReturnPixelReagents(0);
40.       //Pixel.Action = Pixels.ReturnPixelAction(0);
41.       //Pixel.Index = Pixels.ReturnPixelIndex(0);
42.       //Pixel.Position = InsertPosition;
43.       //Map_Pixels.Add(Pixel);
44.       Map.SetPixel(i,j,Color.white);
45.       }
46. }
47. function Update() {
48. var Camera: Camera;
49. Camera = Camera.main;
50. var Ray = Camera.ScreenPointToRay(Input.mousePosition);
51.     var pixelUV : Vector2 = hit.textureCoord;
52.     pixelUV.x *= Map.width;
53.     pixelUV.y *= Map.height;
54.     InsertPosition = pixelUV;
55. Mouse = Input.mousePosition;
56.  
57. Physics.Raycast(Ray,hit,60);
58. if(hit.transform.gameObject != null) {
59. //hit.textureCoord;
60. //pos = hit.point;
61. //InsertPosition = pos;
62. }
63. if(Input.GetKeyDown(KeyCode.Tab)) {
64. ShowInventory = !ShowInventory;
65. }
66. //Mat = transform.GetComponent(Material);
67. Mat.mainTexture = Map;
68. if(Input.GetMouseButtonDown(1)) {
69. DrawnPixel(InsertPosition,Map,Pixel);
70. }
71. TestGravity();
72. }
73. public function DrawnPixel(Position:Vector2,Texture:Texture2D,Pixel:Pixel) {
74. iCount += 1;
75. Pixel.Name = Pixels.ReturnPixelName(InsertPixel);
76. Pixel.Pixel = Pixels.ReturnPixelColor(InsertPixel);
77. Pixel.Reagents = Pixels.ReturnPixelReagents(InsertPixel);
78. Pixel.Action = Pixels.ReturnPixelAction(InsertPixel);
79. Pixel.Index = Pixels.ReturnPixelIndex(InsertPixel);
80. Pixel.Position = InsertPosition;
81.   //Init New Array
82. Map_Pixels.Add(Pixel);
83.  
84. //print("The Array Is"+Map_Pixels);
85.   //Finish New Array
86.  
87.    //Init Old Array
88. //Map_Pixels = new Pixel[iCount];
89. //Map_Pixels.SetValue(Pixel.Name,iCount);
90. //Map_Pixels.SetValue(Pixel.Index,iCount);
91. //Map_Pixels.SetValue(Pixel.Reagents,iCount);
92. //Map_Pixels.SetValue(Pixel.Action,iCount);
93. //Map_Pixels.SetValue(Pixel.Position,iCount);
94.    //Finish Old Array
95. Map.SetPixel(InsertPosition.x,InsertPosition.y,Pixel.Pixel);
96. Map.Apply();
97. TestGravity();
98. }
99. public function GetPixel(Index:int) {
100. Pixel.Name = Pixels.ReturnPixelName(InsertPixel);
101. Pixel.Pixel = Pixels.ReturnPixelColor(InsertPixel);
102. Pixel.Reagents = Pixels.ReturnPixelReagents(InsertPixel);
103. Pixel.Action = Pixels.ReturnPixelAction(InsertPixel);
104. Pixel.Index = Pixels.ReturnPixelIndex(InsertPixel);
105. }
106. function TestGravity() {
107. yield WaitForSeconds(PhysicsDelay);
108. var LPixel: Color;
109. var MPixel: Pixel;
110. var number: int;
111. for(XY.x=0;XY.x<Map.height;XY.x++)
112.    for(XY.y=0;XY.y<Map.width;XY.y++)
113.       {
114.       number = XY.x+XY.y/Map.height/Map.width;
115.      if(number > Map_Pixels.length) {
116.      number = Map_Pixels.length;
117.      }
118.      
119.       LPixel = Map.GetPixel(XY.x,XY.y-1);
120.       MPixel = Map_Pixels[number];
121.       if(LPixel == Color.white) {
122.       MPixel.Position = MPixel.Position-Vector2(MPixel.Position.x,MPixel.Position.y-1);
123.       Map.SetPixel(XY.x,XY.y-1,Map_Pixels[InsertPixel]);
124.       Map.SetPixel(XY.x,XY.y,Color.white);
125.       //FallPixel(XY,MPixel,Map);
126.       print("The Pixel Position is:"+MPixel.Position);
127.       }
128.       }
129.  
130. }
131. function FallPixel(XY:Vector2,Pixel:Pixel,Texture:Texture2D) {
132. Map.SetPixel(XY.x,XY.y-1,Map_Pixels[UseIndex]);
133. Map.SetPixel(XY.x,XY.y,Pixels.Pixels.GetValue(0));
134. Map_Pixels.RemoveAt(iCount);
135. Pixel.Position = XY;
136. Map_Pixels.Add(Pixel);
137. }
138.  
139. //Inventory Function In;
140. function OnGUI() {
141. var localnumber: int;
142. var PixelName: String;
143. if(ShowInventory == true) {
144. for(var i:int=0;i<Pixels.Pixels.Length;i++)
145. for(var j:int=0;j<Pixels.Pixels.Length;j++)
146. {
147. localnumber = i+j/9;
148. if(j == 1) {
149. localnumber += 3;
150. }
151.   if(j == 2) {
152. localnumber += 6;
153. }
154. PixelName = Pixels.ReturnPixelName(localnumber);
155. ItensInInventory = new int[i];
156.   if(GUI.Button(Rect(100*i,50*j,100,50),PixelName)) {
157.   print("The Button is: "+localnumber);
158.   SelectedItemInInventory = localnumber;
159.   InsertPixel = SelectedItemInInventory;
160.   }
161. }
162. }
163. }
164. //Inventory Function Out;

And Pixel class here:

Code (JavaScript):

1. #pragma strict
2.  
3. class Pixel {
4. var Name: String;
5. var Index: int;
6. var Pixel: Color;
7. var Position: Vector2;
8. var Reagents: Color[];
9. var Action: String;
10. }
11. var Pixels: Pixel[];
12.  
13. public function ReturnPixelColor(index:int) : Color
14. {
15.  
16.   for (var i: int =0;i<Pixels.Length;i++)
17.   {
18.     if (Pixels[i].Index == index )
19.     return Pixels[i].Pixel;
20.   }
21. }
22. public function ReturnPixelName(index:int) : String
23. {
24.  
25.   for (var i: int =0;i<Pixels.Length;i++)
26.   {
27.     if (Pixels[i].Index == index )
28.     return Pixels[i].Name;
29.   }
30. }
31. public function ReturnPixelPosition(index:int) : Vector2
32. {
33.  
34.   for (var i: int =0;i<Pixels.Length;i++)
35.   {
36.     if (Pixels[i].Index == index )
37.     return Pixels[i].Position;
38.   }
39. }
40. public function ReturnPixelAction(index:int) : String
41. {
42.  
43.   for (var i: int =0;i<Pixels.Length;i++)
44.   {
45.     if (Pixels[i].Index == index )
46.     return Pixels[i].Action;
47.   }
48. }
49. public function ReturnPixelSpecificReagent(index:int,Reactor:int) : Color
50. {
51.  
52.   for (var i: int =0;i<Pixels.Length;i++)
53.   {
54.     if (Pixels[i].Index == index )
55.     return Pixels[i].Reagents.GetValue(Reactor);
56.   }
57. }
58. public function ReturnPixelReagents(index:int) : Color[]
59. {
60.  
61.   for (var i: int =0;i<Pixels.Length;i++)
62.   {
63.     if (Pixels[i].Index == index )
64.     return Pixels[i].Reagents;
65.   }
66. }
67. public function ReturnPixelIndex(index:int) : int
68. {
69.  
70.   for (var i: int =0;i<Pixels.Length;i++)
71.   {
72.     if (Pixels[i].Index == index )
73.     return Pixels[i].Index;
74.   }
75. }

Please, I need much of response.