「ゲームオブジェクトひとつだけで作るアナログ時計」 (http://tasogare-games.hatenablog.jp/entry/20150422/1429632127)

Main.cs

using UnityEngine;
using System;
using System.Collections;

public class Main : MonoBehaviour
{
    private Transform hours, minutes, seconds;
    private const float
        hoursToDeg = -360f / 12f,
        minutesToDeg = -360f / 60f,
        secondsToDeg = -360f / 60f;

    void Start()
    {
        CreateCamera(0f, 0f, -5f);
        CreateLight(0f, 0f, -5f);

        var tex1 = CreateTextureByColor(Color.blue);
        var tex2 = CreateTextureByColor(Color.red);
        var tex3 = CreateTextureByColor(Color.green);

        hours = CreateHand(0f, 1.0f, 1f, 0.5f, 2.0f, tex1);
        minutes = CreateHand(0f, 1.5f, 0.9f, 0.25f, 3.0f, tex2);
        seconds = CreateHand(0f, 2.0f, 0.8f, 0.1f, 4.0f, tex3);
    }

    void Update()
    {
        var now = DateTime.Now;
        hours.localRotation = Quaternion.Euler(0f, 0f, now.Hour * hoursToDeg);
        minutes.localRotation = Quaternion.Euler(0f, 0f, now.Minute * minutesToDeg);
        seconds.localRotation = Quaternion.Euler(0f, 0f, now.Second * secondsToDeg);
    }

    private Camera CreateCamera(float x, float y, float z)
    {
        var cam = new GameObject().AddComponent<Camera>();
        cam.name = "Camera";
        cam.clearFlags = CameraClearFlags.SolidColor;
        cam.backgroundColor = Color.gray;
        cam.nearClipPlane = 0f;
        cam.farClipPlane = 10f;
        cam.orthographic = true;
        cam.orthographicSize = 5f;
        cam.useOcclusionCulling = true;

        return cam;
    }

    private Light CreateLight(float x, float y, float z)
    {
        var light = new GameObject().AddComponent<Light>();
        light.name = "Light";
        light.type = LightType.Directional;
        light.transform.position = new Vector3(x, y, z);

        return light;
    }

    private Texture2D CreateTextureByColor(Color c)
    {
        var tex = new Texture2D(1, 1, TextureFormat.ARGB32, false);
        tex.SetPixel(0, 0, c);
        tex.Apply();

        return tex;
    }

    private Transform CreateHand(float x, float y, float z, float w, float h, Texture2D tex)
    {
        var cubeTrans = GameObject.CreatePrimitive(PrimitiveType.Cube).transform;
        cubeTrans.localPosition = new Vector3(x, y, z);
        cubeTrans.localScale = new Vector3(w, h, 0.01f);

        var mr = cubeTrans.GetComponent<MeshRenderer>();
        mr.material.mainTexture = tex;

        var container = new GameObject();
        container.name = "Hand";
        cubeTrans.parent = container.transform;

        return container.transform;
    }

}