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AhmedCoeia

Unity Explaining Unity Sprite-Default Shader

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AhmedCoeia    510

I would like to know why we would use alpha blending in that shader for just rendering a sprite, which is just a texture ? What is tint color ? Why we multiply the alpha value by the color here ?

If I just want to draw a 2D GUI Texture(an image) is it ok to remove the tint and the alpha blending from that shader ? 

fixed4 c = tex2D(_MainTex, IN.texcoord) * IN.color; // why ?
c.rgb *= c.a; // why ?
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
Lighting Off
ZWrite Off
Fog { Mode Off }
Blend One OneMinusSrcAlpha

Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma multi_compile DUMMY PIXELSNAP_ON
#include "UnityCG.cginc"

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

struct v2f
{
float4 vertex : SV_POSITION;
fixed4 color : COLOR;
half2 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;

fixed4 frag(v2f IN) : SV_Target
{
fixed4 c = tex2D(_MainTex, IN.texcoord) * IN.color;
c.rgb *= c.a;
return c;
}
ENDCG
}
}
}

 

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