UnityでHPバー等を斜めに表現する方法

よくあるこういうやつ

何も考えずに斜めにした画像バー用意してやっても期待したとおり動かない．
BaseMeshEffectクラスを拡張して描画させるとよい．
コードは以下．

using UnityEngine;
using UnityEngine.UI;
using System.Collections;
using System.Collections.Generic;

/// <summary>
/// 四角形を平行四辺形に変更します
/// </summary>
public class ChangeUIToParallelogram : BaseMeshEffect {

	/// <summary>左側か右側か向きを決めます</summary>
	public bool isLeft;

	/// <summary>水平線とのなす角</summary>
	[Range (0, 75)]
	public int angle = 30;

	public override void ModifyMesh (Mesh in_mesh)
	{
		if (!this.IsActive ()) return;

		List<UIVertex> list = new List<UIVertex> ();
		using (VertexHelper vertexHelper = new VertexHelper (in_mesh)) 
		{
			vertexHelper.GetUIVertexStream (list);
		}

		this.ModifyVertices (list);

		using (VertexHelper vertexHelper2 = new VertexHelper ()) 
		{
			vertexHelper2.AddUIVertexTriangleStream (list);
			vertexHelper2.FillMesh (in_mesh);
		}
			
	}

	public override void ModifyMesh(VertexHelper in_vh)
	{
		if (!this.IsActive())
			return;

		List<UIVertex> vertexList = new List<UIVertex>();
		in_vh.GetUIVertexStream(vertexList);

		ModifyVertices(vertexList);

		in_vh.Clear();
		in_vh.AddUIVertexTriangleStream(vertexList);
	}

	public void ModifyVertices (List<UIVertex> in_vList) 
	{
		if (this.IsActive() == false || in_vList == null || in_vList.Count == 0 ) return;

		Vector3 vec = in_vList[1].position - in_vList[0].position;
		float h = vec.y;
		float fac = h * Mathf.Tan (Mathf.Deg2Rad * this.angle);
		float left = (this.isLeft)? fac : 0f;
		float right = (this.isLeft)? 0f : fac;

		List<Vector3> v = new List<Vector3> ();
		v.Add (new Vector3 (left,0f,0f));
		v.Add (new Vector3 (right,0f,0f));
		v.Add (new Vector3 (right,0f,0f));
		v.Add (new Vector3 (right,0f,0f));
		v.Add (new Vector3 (left,0f,0f));
		v.Add (new Vector3 (left,0f,0f));

		for (int i=0; i<in_vList.Count; i++) {
			UIVertex tmpV = in_vList[i];
			tmpV.position += v[i];
			in_vList[i] = tmpV;
		}
	}

}

このスクリプトをuGUIのImageオブジェクトに適用させるといいかんじに斜めバーが作れる

unityのversionは5.2.2f