Sprite obstruction transparent area

Question

I am trying to build a system in my game that will make sprite tiles that are in front of my character semi-transparent. It is simple enough to adjust the alpha channel on the sprite renderer material but the problem with that is the tile borders then become very apparent and is pretty ugly. What I would like to do is have a way to feed it a beginning and end value for alpha so I can have it create a nice alpha gradient along the x axis. How might I go about this? Do I create a custom shader? Any examples? I have googled this until I was blue in the face but I must not be searching for the right thing because could not find anything.

Thanks!

Answer 1

Ok, after bouncing my head off this task for awhile I think I have nailed what I need so I will share with the class.

Here is my modified sprite shader

 Shader "Sprites/AlphaGradient"
 {
     Properties
     {
         [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
         _Color ("Tint", Color) = (1,1,1,1)
         [MaterialToggle] PixelSnap ("Pixel snap", Float) = 0
         [MaterialToggle] _UseFade ("Use Fade", Float) = 0
         _FadeOrigin ("Fade Origin", vector) = (1,1,1)
         _FadeAreaMin ("Fade Area Min", float) = 1.5
         _FadeAreaMax ("Fade Area Max", float) = 2.5
         _MaxOpacity ("Max Opacity", Range(0,1)) = 0.5
     }
 
     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;
                 float4 objCoords : TEXCOORD1;
                 fixed4 color    : COLOR;
                 half2 texcoord  : TEXCOORD0;
             };
             
             fixed4 _Color;
 
             v2f vert(appdata_t IN)
             {
                 v2f OUT;
                 OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
                 OUT.objCoords = mul(_Object2World, IN.vertex);
                 OUT.texcoord = IN.texcoord;
                 OUT.color = IN.color * _Color;
                 #ifdef PIXELSNAP_ON
                 OUT.vertex = UnityPixelSnap (OUT.vertex);
                 #endif
 
                 return OUT;
             }
 
             sampler2D _MainTex;
             float _UseFade;
             float _FadeAreaMin;
             float _FadeAreaMax;
             vector _FadeOrigin;
             float _MaxOpacity;
 
             fixed4 frag(v2f IN) : SV_Target
             {
                 fixed4 c = tex2D(_MainTex, IN.texcoord) * IN.color;
                 float percent = 1;
                 
                 if(_UseFade == 1)
                 {
                     float pixDist = distance(_FadeOrigin.xy, IN.objCoords.xy);
 
                     if(pixDist < _FadeAreaMin)
                     {
                         percent = _MaxOpacity;
                     }
                     else
                     {
                         if(_FadeAreaMin > _FadeAreaMax)
                         {
                             _FadeAreaMin = _FadeAreaMax;
                         }
                         
                         if(_FadeAreaMax < _FadeAreaMin)
                         {
                             _FadeAreaMax = _FadeAreaMin;
                         }
 
                         if(pixDist > _FadeAreaMin && pixDist < _FadeAreaMax)
                         {
                             float fadeAreaSize = _FadeAreaMax - _FadeAreaMin;
                             float pixPos = pixDist - _FadeAreaMin;
                             float fadePercent = pixPos/fadeAreaSize;
                             
                             if(fadePercent < _MaxOpacity)
                             {
                                 fadePercent = _MaxOpacity;
                             }
                             
                             percent = fadePercent;
                         }
                     }
                 }
 
                 c.rgba *= c.a * percent;
                 
                 return c;
             }
         ENDCG
         }
     }
 }

And below is how it looks. It will create a fade effects from the origin point. I hope this helps some people because for this shader noob it was quite a challenge.

alt text

Sprite obstruction transparent area

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