SpriteMaskHelper.cs

using UnityEngine;
using System.Collections;
using ToJ;

public class SpriteMaskHelper : MonoBehaviour
{
    static readonly string SHADER_ALPHA_MASK_SPRITE = "Alpha Masked/Sprites Alpha Masked - World Coords";
    static readonly string SHADER_VAR_USEALPHACHANNEL = "_UseAlphaChannel";
    static readonly string SHADER_VAR_ALPHATEX = "_AlphaTex";

    [SerializeField, Tooltip("Set a specific mask, or leave empty to find mask automatically")] Mask m_mask = null;

    static Shader s_alphaMaskShader = null;

    /// Sets up the sprite to  be masked, and moves it under the sprite object
    public void AddSprite(SpriteRenderer sprite)
    {
        if ( m_mask == null )
            m_mask = GetComponentInChildren<Mask>();

        if ( m_mask == null || sprite == null)
            return;

        if ( s_alphaMaskShader == null )
            s_alphaMaskShader = Shader.Find(SHADER_ALPHA_MASK_SPRITE);

        sprite.material.shader = s_alphaMaskShader;
        m_mask.SetMaskBoolValueInMaterial(SHADER_VAR_USEALPHACHANNEL,true,sprite.material);
        m_mask.SetMaskMappingAxisInMaterial(Mask.MappingAxis.Z,sprite.material);
        sprite.material.SetTexture(SHADER_VAR_ALPHATEX, m_mask.GetComponent<MeshRenderer>().materials[0].mainTexture);
        sprite.transform.SetParent( m_mask.transform.parent, true);
    }
}