FakeRenderCubemapFace

using UnityEngine;
using System.Collections;

public class FakeRenderCubemapFace : MonoBehaviour {
    private Texture2D texture;
    public Cubemap cubemap;
    public CubemapFace cubemapFace;
    public float updateFrequency = .5f;
    private float lastUpdate = 0f;
    private Rect sourceRect;

    // Use this for initialization
    void Start() {
        float x = 0;
        float y = cubemap.height;
        if (cubemapFace == CubemapFace.PositiveZ) {
            x = cubemap.width;
        }
        if (cubemapFace == CubemapFace.PositiveX) {
            x = cubemap.width * 2;
        }
        if (cubemapFace == CubemapFace.NegativeZ) {
            x = cubemap.width * 3;
        }
        if (cubemapFace == CubemapFace.PositiveY) {
            y = cubemap.width * 2;
        }
        if (cubemapFace == CubemapFace.NegativeY) {
            y = 0;
        }
        texture = new Texture2D (cubemap.width, cubemap.height);
        sourceRect = new Rect (x, y, cubemap.width, cubemap.height);
        camera.pixelRect = sourceRect;
    }

    void Update() {
        if (Time.time > lastUpdate + updateFrequency) {
            camera.enabled = true;
            lastUpdate = Time.time;
        }
    }

    void OnPostRender() {
        texture.ReadPixels (sourceRect, 0, 0);
        cubemap.SetPixels (texture.GetPixels (), cubemapFace);
        camera.enabled = false;
    }
}