builtin_shaders-5.3.4f1学习-Sprites-Default

Shader "Sprites/Default"
{
Properties
{
[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
_Color ("Tint", Color) = (1,1,1,1)
[MaterialToggle] PixelSnap ("Pixel snap", Float) = 0
}

SubShader
{
Tags
{
"Queue"="Transparent"
"IgnoreProjector"="True"
"RenderType"="Transparent"
"PreviewType"="Plane"
"CanUseSpriteAtlas"="True"
}

Cull Off         //关闭背面剔除
Lighting Off     //关闭灯光
ZWrite Off       //关闭Z缓冲
Blend One OneMinusSrcAlpha     //混合源系数one(1)  目标系数OneMinusSrcAlpha(1-one=0)

Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma multi_compile _ PIXELSNAP_ON       //告诉Unity编译不同版本的Shader,这里和后面vert中的PIXELSNAP_ON对应
#pragma shader_feature ETC1_EXTERNAL_ALPHA
#include "UnityCG.cginc"

struct appdata_t                           //vert输入
{
float4 vertex   : POSITION;
float4 color    : COLOR;
float2 texcoord : TEXCOORD0;
};

struct v2f                                 //vert输出数据结构
{
float4 vertex   : SV_POSITION;
fixed4 color    : COLOR;
float2 texcoord  : TEXCOORD0;
};

fixed4 _Color;

v2f vert(appdata_t IN)
{
v2f OUT;
OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
OUT.texcoord = IN.texcoord;
OUT.color = IN.color * _Color;
#ifdef PIXELSNAP_ON
OUT.vertex = UnityPixelSnap (OUT.vertex);
#endif

return OUT;
}

sampler2D _MainTex;
sampler2D _AlphaTex;

fixed4 SampleSpriteTexture (float2 uv)
{
fixed4 color = tex2D (_MainTex, uv);

#if ETC1_EXTERNAL_ALPHA         //etc1没有透明通道，从另一图中取a值
// get the color from an external texture (usecase: Alpha support for ETC1 on android)
color.a = tex2D (_AlphaTex, uv).r;
#endif //ETC1_EXTERNAL_ALPHA

return color;
}

fixed4 frag(v2f IN) : SV_Target
{
fixed4 c = SampleSpriteTexture (IN.texcoord) * IN.color;
c.rgb *= c.a;
return c;
}
ENDCG
}
}
}