Gradient

Shader "Cale/TweenGradient" {
    Properties {
        _color1 ("Grad 1 Color 1", Color) = (1,.5,.5,1)
        _color2 ("Grad 1 Color 2", Color) = (.5,1,1,1)
        _color3 ("Grad 2 Color 1", Color) = (.5,1,.5,1)
        _color4 ("Grad 2 Color 2", Color) = (.5,.5,1,1)
        _offset("Interpolation Offset",Float)=0
        _speed("Interpolation Speed",Float)=1
        _MainTex ("SelfIllum Color (RGB) Alpha (A)", 2D) = "white"{}
    }
    Category{
        Blend SrcAlpha OneMinusSrcAlpha
        Tags {Queue=Transparent}
        SubShader {
            Pass{

                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag

                float4 _color1;
                float4 _color2;
                float4 _color3;
                float4 _color4;
                float _offset;
                float _speed;
                sampler2D _MainTex;

                struct appdata {
                    float4 vertex : POSITION;
                    float4 tex : TEXCOORD0;
                };
                struct v2f {
                    float4 vertex : TEXCOORD;
                    float4 pos : POSITION;
                };
                v2f vert(appdata v) {
                    v2f o;
                    o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                    o.vertex = v.tex;
                    return o;
                };

                half4 frag(v2f i) : COLOR {
                    float _inter = sin(_offset+_Time.y*_speed)*.5+.5;
                    _color1.rgba = (_color1.rgba*i.vertex.y+_color2.rgba*(1-i.vertex.y))*_inter+(_color3.rgba*i.vertex.y+_color4.rgba*(1-i.vertex.y))*(1-_inter);
                    _color1.rgb = _color1.rgb*tex2D(_MainTex,i.vertex.xy).rgb;
                    return _color1;
                };

                ENDCG
            }
        }
    }
    FallBack "Diffuse"
}