Create all same mesh but with an inversed side

[Shayan]

Hi, guys!
I try to create mesh in 2D game (I need a complex sprite shape):

Mesh mesh = new Mesh();
mesh.name = "PolygonMesh";
mesh.vertices = new Vector3[] {
    new Vector3(-1f, -1f, 0f),
    new Vector3(1f, -1f, 0f),
    new Vector3(1f, 1f, 0f),
    new Vector3(-1f, 1f, 0f)
};
mesh.uv = new Vector2[] {
    new Vector2 (0, 0),
    new Vector2 (0, 1),
    new Vector2 (1, 1),
    new Vector2 (1, 0)
};
mesh.triangles = new int[] { 0, 1, 2, 0, 2, 3 };
mesh.RecalculateNormals();

But this mesh has a face side that is inverted toward to another scene’s objects. Of course, I can rotate it on 180 deg. by Y-axis but I want create it already inversed to reduce additional transform calculations for rotating. How to make it?

[villevli]

You can reverse the triangles

mesh.triangles = new int[] { 2, 1, 0, 3, 2, 0 };

[Shayan]

@villevli

You can reverse the triangles

mesh.triangles = new int[] { 2, 1, 0, 3, 2, 0 };

Yeah, thank you! But can you explain me, pls? Why it so? How to vertex path order influences on the face side?
Maybe it has a lot of information but I don’t know how it is called to find.

[villevli]

@Shayan

Yeah, thank you! But can you explain me, pls? Why it so? How to vertex path order influences on the face side?
Maybe it has a lot of information but I don’t know how it is called to find.

http://docs.unity3d.com/Manual/UsingtheMeshClass.html

The triangles are specified as triples of integers that act as indices into the vertex array. Rather than use a special class to represent a triangle the array is just a simple list of integer indices. These are taken in groups of three for each triangle, so the first three elements define the first triangle, the next three define the second triangle, and so on. An important detail of the triangles is the ordering of the corner vertices. They should be arranged so that the corners go around clockwise as you look down on the visible outer surface of the triangle, although it doesn’t matter which corner you start with.

[Shayan]

@villevli

http://docs.unity3d.com/Manual/UsingtheMeshClass.html

Thank you very much! It seems, I understood all.