Apply Textures to Only Certain Faces of a Cube in Unity

Question

I am trying to make realistic-looking procedurally generated buildings. So far I have made a texture generation program for them. I would like to apply that texture to a simple cube in Unity, however, I don't want to apply the texture to all of the faces. Currently when I apply the texture to the cube's material it apply's the same texture to all of the faces and on some of the faces the texture is upside down. Do you recommend that I make plane objects and apply the textures to each of those (and form a cube that way). I know this would work, but is it efficient at a large scale? Or is there a way to apply different textures to individual faces of a cube in C#?

Answer 1

Considering that you are trying to create buildings you should procedurally generate your own 'cube'/building mesh data.

For example:

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public Vector3[] newVertices;
    public Vector2[] newUV;
    public int[] newTriangles;
    void Start() {
        Mesh mesh = new Mesh();
        mesh.vertices = newVertices;
        mesh.uv = newUV;
        mesh.triangles = newTriangles;
        GetComponent<MeshFilter>().mesh = mesh;
    }
}

Then you populate the verticies, and tris with data. For example, you could create a small 1 by 1 cube around origin 0 with:

int size = 1;
newVertices = new Vector3[]{
    Vector3(-size, -size,  -size),
    Vector3(-size,  size,  -size),
    Vector3( size,  size,  -size),
    Vector3( size, -size,  -size),
    Vector3( size, -size,   size),
    Vector3( size,  size,   size),
    Vector3(-size,  size,  size),
    Vector3(-size, -size,  size)
};

Then because you only want to render the texture on 1 of the meshes faces;

 newUV = new Vector2[]{
    Vector2(0,0), 
    Vector2(0,1),
    Vector2(1,0), 
    Vector2(1,1),
    Vector2(0,0), 
    Vector2(0,0),
    Vector2(0,0),
    Vector2(0,0),
    Vector2(0,0),
    Vector2(0,0),
    Vector2(0,0), 
    Vector2(0,0)
};

Note that only allocating UV coords for some of the verts This will effectively only place your desired texture on 1 of the faces and then depending on how you allocate the tris, the rest of the UVs can be altered as you see fit to appear as though they are untextured.

Please note that I wrote this with out an IDE so there may be some syntax errors. Also, this isn't the most straight forward process, but I promise that it far exceeds the use of a series of quads as a building because with this you can make a whole range of shapes 'easily'.

Resources:

http://docs.unity3d.com/ScriptReference/Mesh.html

https://msdn.microsoft.com/en-us/library/windows/desktop/bb205592%28v=vs.85%29.aspx

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