UV mapping

I have listed all the ways to custom UV map a unity cube here : http://answers.unity3d.com/questions/294165/apply-uv-coordinates-to-unity-cube-by-script.html

Imagine looking at the front of the cube, the first 4 vertices are arranged like so

 //   2 --- 3
 //   |     |
 //   |     |
 //   0 --- 1

then the UV's are mapped as follows :

 theUVs[2] = Vector2( 0, 1 );
 theUVs[3] = Vector2( 1, 1 );
 theUVs[0] = Vector2( 0, 0 );
 theUVs[1] = Vector2( 1, 0 );

 //    2    3    0    1   Front
 //    6    7   10   11   Back
 //   19   17   16   18   Left
 //   23   21   20   22   Right
 //    4    5    8    9   Top
 //   15   13   12   14   Bottom

So where the UV's for Vertices 2 is ( 0, 1 ), so is 6, 19, 23, 4, 15.

You can test this by replacing all the zero's with 0.5, then check every face of the cube has the same portion of the image, and rotated the correct way (not inverted) . Note if standing at the origin looking up the positive Z-Axis, Right is your right.

for example this script would map the TOP of the cube to any UV coordinates of a texture you like :

 #pragma strict
 // TOP
 
 function Start() 
 {
     // Get the mesh
     var theMesh : Mesh;
     theMesh = this.transform.GetComponent(MeshFilter).mesh as Mesh;
 
     // Now store a local reference for the UVs
     var theUVs : Vector2[] = new Vector2[theMesh.uv.Length];
     theUVs = theMesh.uv;
 
     // set UV co-ordinates
     theUVs[4] = Vector2( 0.5, 1.0 );
     theUVs[5] = Vector2( 1.0, 1.0 );
     theUVs[8] = Vector2( 0.5, 0.5 );
     theUVs[9] = Vector2( 1.0, 0.5 );
 
     // Assign the mesh its new UVs
     theMesh.uv = theUVs;
 }

---

EDIT, In reply to : So if I create a texture atlas and assign sections to the different sides of the cube, is it possible to tile each side differently? Or would everything get tiled by the same amount? Cheers for the help, Muzzstick.

Me : I think an example scene would be a good visual demonstration. First, grab this texture : http://metaverse.mitsi.com/Secondlife/posts/uvmaps/images/uv_checker%20large.png

Now create a new scene, create a cube and attach that texture as a material. Create a new script and attach it to the cube. Copy in the below code, then hit play.

You see for each face a different part of the texture has been assigned, this is basically UV mapping. Change the values in the cube Inspector, then hit the Left mouse button. First try changing the width and height just to see the effects. Then change the x and the y for different start positions on the texture.

Hopefully this shows what UV mapping is, and how it usually applies to one texture atlas (sometimes called a texture map). Again, for a different texture, the plane method is the way to do it.

Anyway, here is the code :

 #pragma strict
 
 // using an image that is an 8x8 grid
 // each image is 0.125 in width and 0.125 in height of the full image
 
 // UVs in this example are given as a Rect
 // uvs : start position X, start position y, width, height
 // start positions are staggered to show different images
 // width and height are set to 0.125 (1/8th square of the full image)
 
 public var uvsFront : Rect = new Rect( 0.0, 1.0, 0.125, 0.125 );
 public var uvsBack : Rect = new Rect( 0.125, 0.875, 0.125, 0.125 );
 public var uvsLeft : Rect = new Rect( 0.25, 0.75, 0.125, 0.125 );
 public var uvsRight : Rect = new Rect( 0.375, 0.625, 0.125, 0.125 );
 public var uvsTop : Rect = new Rect( 0.5, 0.5, 0.125, 0.125 );
 public var uvsBottom : Rect = new Rect( 0.625, 0.375, 0.125, 0.125 );
 
 private var theMesh : Mesh;
 private var theUVs : Vector2[];
 private var xOffset : float = 0.0;
 
 function Start() 
 {
     theMesh = transform.GetComponent(MeshFilter).mesh;
     theUVs = new Vector2[theMesh.uv.Length];
     theUVs = theMesh.uv;
     
     SetUVs();
 }
 
 function Update() 
 {
     // change the UV settings in the Inspector, then click the left mouse button to view
     if ( Input.GetMouseButtonUp(0) )
     {
         SetUVs();
     }
 }
 
 // 2 --- 3
 // |     |
 // |     |
 // 0 --- 1
 
 function SetUVs() 
 {
     // - set UV coordinates -
     
     // FRONT    2    3    0    1
     theUVs[2] = Vector2( uvsFront.x, uvsFront.y );
     theUVs[3] = Vector2( uvsFront.x + uvsFront.width, uvsFront.y );
     theUVs[0] = Vector2( uvsFront.x, uvsFront.y - uvsFront.height );
     theUVs[1] = Vector2( uvsFront.x + uvsFront.width, uvsFront.y - uvsFront.height );
     
     // BACK    6    7   10   11
     theUVs[6] = Vector2( uvsBack.x, uvsBack.y );
     theUVs[7] = Vector2( uvsBack.x + uvsBack.width, uvsBack.y );
     theUVs[10] = Vector2( uvsBack.x, uvsBack.y - uvsBack.height );
     theUVs[11] = Vector2( uvsBack.x + uvsBack.width, uvsBack.y - uvsBack.height );
     
     // LEFT   19   17   16   18
     theUVs[19] = Vector2( uvsLeft.x, uvsLeft.y );
     theUVs[17] = Vector2( uvsLeft.x + uvsLeft.width, uvsLeft.y );
     theUVs[16] = Vector2( uvsLeft.x, uvsLeft.y - uvsLeft.height );
     theUVs[18] = Vector2( uvsLeft.x + uvsLeft.width, uvsLeft.y - uvsLeft.height );
     
     // RIGHT   23   21   20   22
     theUVs[23] = Vector2( uvsRight.x, uvsRight.y );
     theUVs[21] = Vector2( uvsRight.x + uvsRight.width, uvsRight.y );
     theUVs[20] = Vector2( uvsRight.x, uvsRight.y - uvsRight.height );
     theUVs[22] = Vector2( uvsRight.x + uvsRight.width, uvsRight.y - uvsRight.height );
     
     // TOP    4    5    8    9
     theUVs[4] = Vector2( uvsTop.x, uvsTop.y );
     theUVs[5] = Vector2( uvsTop.x + uvsTop.width, uvsTop.y );
     theUVs[8] = Vector2( uvsTop.x, uvsTop.y - uvsTop.height );
     theUVs[9] = Vector2( uvsTop.x + uvsTop.width, uvsTop.y - uvsTop.height );
     
     // BOTTOM   15   13   12   14
     theUVs[15] = Vector2( uvsBottom.x, uvsBottom.y );
     theUVs[13] = Vector2( uvsBottom.x + uvsBottom.width, uvsBottom.y );
     theUVs[12] = Vector2( uvsBottom.x, uvsBottom.y - uvsBottom.height );
     theUVs[14] = Vector2( uvsBottom.x + uvsBottom.width, uvsBottom.y - uvsBottom.height );
      
     // - Assign the mesh its new UVs -
     theMesh.uv = theUVs;
 }

 theUVs[4] = Vector2( 0.5, 1.0 ); // top left
 theUVs[5] = Vector2( 1.0, 1.0 ); // top right
 theUVs[8] = Vector2( 0.5, 0.5 ); // bottom left
 theUVs[9] = Vector2( 1.0, 0.5 ); // bottom right