Unity中對sprite renderer圖檔做進度條效果

項目裡條件限制，隻能使用sprite renderer來做UI，原來做進度條效果都是用ngui或者ugui裡寫好的fill屬性。想到肯定可以用shader來實作，但是無奈自己并不會寫 T T 。找到個能用的shader，記錄下位址：

http://www.ceeger.com/forum/read.php?tid=3492;ds=1#tpc

感謝原作者。

shader的内容：

Shader "Custom/CursorLoadShader" {
    Properties 
    {
        _Color ("Main Color", Color) = (,,,)
            _MainTex ("Base (RGB) Trans (A)", D) = "white" {}
            _MaskTex ("Mask (A)", D) = "white" {}
            _Progress ("Progress", Range(,)) = 
    }

    Category 
    {
        Lighting Off
        ZWrite Off
        Cull back
        Fog { Mode Off }
        Tags {"Queue"="Transparent" "IgnoreProjector"="True"}
        Blend SrcAlpha OneMinusSrcAlpha
        SubShader 
        {
            Pass 
            {
                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                sampler2D _MainTex;
                sampler2D _MaskTex;
                fixed4 _Color;
                float _Progress;
                struct appdata
                {
                    float4 vertex : POSITION;
                    float4 texcoord : TEXCOORD0;
                };
                struct v2f
                {
                    float4 pos : SV_POSITION;
                    float2 uv : TEXCOORD0;
                };
                v2f vert (appdata v)
                {
                    v2f o;
                    o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                    o.uv = v.texcoord.xy;
                    return o;
                }
                half4 frag(v2f i) : COLOR
                {
                    fixed4 c = _Color * tex2D(_MainTex, i.uv);
                    fixed ca = tex2D(_MaskTex, i.uv).a;
                    c.a *= ca >= _Progress ?  : ;
                    return c;
                }
                ENDCG
            }
        }

        SubShader 
        {           
            AlphaTest LEqual [_Progress]  
            Pass  
            {  
                SetTexture [_MaskTex] {combine texture}  
                SetTexture [_MainTex] {combine texture, previous}  
            }  
        }

    }
    Fallback "Transparent/VertexLit"
}
           

圓環形遮罩圖檔