Draw Polygon

Hey there,

I would like unity to draw a 3D polygon during run-time based on the location of some Vector3 vertices

I want the entire polygon to be filled (no wireframe).

For example, the following would draw a square:

Code (csharp):

1.  
2. var theVertices = new Array();
3.  
4. theVertices.Push(Vector3((0,0,0));
5. theVertices.Push(Vector3((1,0,0));
6. theVertices.Push(Vector3((1,1,0));
7. theVertices.Push(Vector3((0,1,0));
8.  
9. DrawPoly(theVertices);
10.  

Suggestions?

 

http://unity3d.com/support/documentation/ScriptReference/MeshFilter.html
http://unity3d.com/support/documentation/ScriptReference/Mesh.html

 

Thanks for the reply.

It looks like I have to create a new mesh. The example they provide:

Code (csharp):

1.  
2. function Start  ()
3. {
4.      var mesh = new Mesh ();
5.      GetComponent (MeshFilter).mesh = mesh;
6.      mesh.vertices = newVertices;
7.      mesh.uv = newUV;
8.      mesh.triangles = newTriangles;
9. }
10.  

I'm assuming that newVerticies, newUV, and newTriangles are all the arrays of data that I would have offhand. I'm then assigning this data to the mesh. Makes sense. Some questions:

1) I'm looking at a function, Graphics.DrawMesh(). I can use this to draw the mesh I create without having to create a game object right?

2A) Can I also assign this mesh to a new game object and have it draw it for me automatically? Something like this?:

Code (csharp):

1.  
2. var mesh : Mesh;
3. var gameObject : GameObject;
4.  
5. CreateMesh()
6. {
7.    var meshCreated : Mesh = new Mesh();
8.    ///blah blah blah, create some mesh
9.    return meshCreated
10. }
11.  
12. mesh = CreateMesh();
13.  
14. gameObject.AddComponent("MeshFilter");
15. gameObject.AddComponent("MeshRenderer");
16.  
17. gameObject.MeshFilter.mesh = mesh;
18.  

2B) How can I change the material for this game object? Something like this?:

Code (csharp):

1.  
2. var myMaterial : Material; //Drag and drop a material onto the inspector
3.  
4. gameObject.MeshRenderer.Materials[0] = myMaterial;
5.  

Thanks,
Alex

 

Got it working thanks.

If anyone is curious, here is my code

Code (csharp):

1.  
2. function updatePolygon()
3. {
4.     for(x = 0; x < 2; x++)
5.     {
6.         //Destroy old game object
7.         Destroy(myObject[x]);
8.  
9.         //New mesh and game object
10.         myObject[x] = new GameObject();
11.         myObject[x].name = "MousePolygon";
12.         var mesh : Mesh = new Mesh();
13.        
14.         //Components
15.         var MF = myObject[x].AddComponent("MeshFilter");
16.         var MR = myObject[x].AddComponent("MeshRenderer");
17.         //myObject[x].AddComponent();
18.        
19.         //Create mesh
20.         mesh = CreateMesh(x);
21.        
22.         //Assign materials
23.         MR.material = myMaterial;
24.        
25.         //Assign mesh to game object
26.         MF.mesh = mesh;
27.     }
28. }
29.  

Code (csharp):

1.  
2. function CreateMesh(num : int)
3. {
4.     var x : int; //Counter
5.  
6.     //Create a new mesh
7.     var mesh : Mesh = new Mesh();
8.    
9.     //Vertices
10.     var vertex = new Vector3[nodePositions.length];
11.    
12.     for(x = 0; x < nodePositions.length; x++)
13.     {
14.         vertex[x] = nodePositions[x];
15.     }
16.    
17.     //UVs
18.     var uvs = new Vector2[vertex.length];
19.    
20.     for(x = 0; x < vertex.length; x++)
21.     {
22.         if((x%2) == 0)
23.         {
24.             uvs[x] = Vector2(0,0);
25.         }
26.         else
27.         {
28.             uvs[x] = Vector2(1,1);
29.         }
30.     }
31.    
32.     //Triangles
33.     var tris = new int[3 * (vertex.length - 2)];    //3 verts per triangle * num triangles
34.     var C1 : int;
35.     var C2 : int;
36.     var C3 : int;
37.    
38.     if(num == 0)
39.     {
40.         C1 = 0;
41.         C2 = 1;
42.         C3 = 2;
43.        
44.         for(x = 0; x < tris.length; x+=3)
45.         {
46.             tris[x] = C1;
47.             tris[x+1] = C2;
48.             tris[x+2] = C3;
49.            
50.             C2++;
51.             C3++;
52.         }
53.     }
54.     else
55.     {
56.         C1 = 0;
57.         C2 = vertex.length - 1;
58.         C3 = vertex.length - 2;
59.        
60.         for(x = 0; x < tris.length; x+=3)
61.         {
62.             tris[x] = C1;
63.             tris[x+1] = C2;
64.             tris[x+2] = C3;
65.            
66.             C2--;
67.             C3--;
68.         }  
69.     }
70.    
71.     //Assign data to mesh
72.     mesh.vertices = vertex;
73.     mesh.uv = uvs;
74.     mesh.triangles = tris;
75.    
76.     //Recalculations
77.     mesh.RecalculateNormals();
78.     mesh.RecalculateBounds();  
79.     mesh.Optimize();
80.    
81.     //Name the mesh
82.     mesh.name = "MyMesh";
83.    
84.     //Return the mesh
85.     return mesh;
86. }
87.  

This creates a mesh and attaches it to two game objects. The mesh is stitched counter-clockwise in one object, and clockwise in another game object. Then both objects are drawn on top of each other. The reason I do this is so that way the object is visible on the front and back.

 

Glad to see you got that working Just out of curiosity, why do you destroy the game objects each update, rather than just using go.GetComponent("MeshFilter").mesh.Clear()?

 

Cause im bad!

Thanks for the pro tip

 

Hi Alex,

How did you actually get this to work? How to set up a scene without gameobjects to start with?

Where does the data input into these scripts come from?

thanks!

 

Any one has a sample project for drawing polygon please?

 

If you want to draw a polygon in the new UI check this out: https://github.com/CiaccoDavide/Unity-UI-Polygon

 

I'm torn between complimenting what appears to be a useful and free plugin, or blasting you for necroposting just to spam your own plugin...

 

god plugin