title: How to transparent Unity3D custom shader?
body: <p>I have a custom shader which can render texture inside an object (such as : Sphere). But <strong>I can't make it transparent because Unity says there is no <code>_Color</code> property added in that shader.</strong></p>
  
  <p>I am not an expert in Unity Shader, so need some help how to make my existing shader. Here is my shader code.</p>
  
  <pre><code>Shader "InsideVisible" 
  {
      Properties 
      {
          _MainTex ("Base (RGB)", 2D) = "white" {}
      }
  
      SubShader 
      {
          Tags { "RenderType"="Opaque" }
          Cull front
          LOD 100
  
          Pass 
          {  
              CGPROGRAM
              #pragma vertex vert
              #pragma fragment frag
  
              #include "UnityCG.cginc"
  
              struct appdata_t {
                  float4 vertex : POSITION;
                  float2 texcoord : TEXCOORD0;
              };
  
              struct v2f {
                  float4 vertex : SV_POSITION;
                  half2 texcoord : TEXCOORD0;
              };
  
              sampler2D _MainTex;
              float4 _MainTex_ST;
  
              v2f vert (appdata_t v)
              {
                  v2f o;
  
                  o.vertex     = mul(UNITY_MATRIX_MVP, v.vertex);
                  v.texcoord.x = 1 - v.texcoord.x;                
                  o.texcoord   = TRANSFORM_TEX(v.texcoord, _MainTex);
  
                  return o;
              }
  
              fixed4 frag (v2f i) : SV_Target
              {
                  fixed4 col = tex2D(_MainTex, i.texcoord);
                  return col;
              }
  
              ENDCG
          }
      }
  }
  </code></pre>