Shader problem: Transparency removed with Opacity changes

Hello! I am trying to make a shader that takes in 2 textures and blends them together, and then the final output needs to have opacity as a variable. To that end, I have gotten it all worked out, EXCEPT, whenever one of the inputs has transparency, the opacity element removes the transparency and replaces it with this:

my code so far:

Code (CSharp):

1. Shader "Custom/TonyShader2D"
2. {
3.     Properties
4.     {
5.         _MainTex ("Albedo (RGB)", 2D) = "white" {}
6.         _OffTex ("Other Texture", 2D) = "white" {}
7.         _Strength ("Blend Strength Between Textures", Range(0,1)) = 1
8.         _Opacity ("Opacity", Range(0,1)) = 0.0
9.     }
10.     SubShader
11.     {
12.         Tags { "Queue"="Transparent"  "RenderType"="Transparent" }
13.  
14.          Blend SrcAlpha OneMinusSrcAlpha
15.         Pass
16.         {
17.         CGPROGRAM
18.  
19.         #pragma vertex vert
20.         #pragma fragment frag
21.        
22.         #include "UnityCG.cginc"
23.  
24.  
25.         sampler2D _MainTex;
26.         sampler2D _OffTex;
27.  
28.         half _Opacity;
29.         half _Strength;
30.  
31.         float4 _MainTex_ST;
32.         float4 _OffTex_ST;
33.  
34.         struct Input
35.         {
36.             float2 uv_MainTex;
37.             float2 uv_OffTex;
38.         };
39.  
40.  
41.             struct v2f
42.             {
43.                 float4 vertex : SV_POSITION;
44.                 float2 uv : TEXCOORD0;
45.                 float2  uv2 : TEXCOORD1;
46.             };
47.  
48.             v2f vert(appdata_base v)
49.             {
50.                 v2f o;
51.                 o.vertex = UnityObjectToClipPos(v.vertex);
52.                 o.uv = TRANSFORM_TEX (v.texcoord, _MainTex);
53.                 o.uv2 = TRANSFORM_TEX (v.texcoord, _OffTex);
54.                 return o;
55.             }
56.  
57.  
58.         //void surf (Input IN, inout SurfaceOutputStandard o)
59.         float4 frag(v2f i) : SV_Target
60.         {
61.             fixed4 c = tex2D (_MainTex, i.uv);
62.             //c.a= _Opacity;
63.             fixed4 c2 = tex2D (_OffTex, i.uv2);
64.             //c2.a= _Opacity;
65.             fixed4 c3 = lerp (c, c2, _Strength);
66.             c3.a= _Opacity;
67.             return c3;
68.         }
69.         ENDCG
70.     }
71. }}

Any Ideas?

 

This is to be expected: you're throwing away your texture's alpha channel and entirely replacing with your _Opacity value.

Code (CSharp):

1. c3.a = _Opacity;

You should multiply (modulate) your alpha channel by _Opacity instead:

Code (CSharp):

1. c3.a *= _Opacity;

 

Thank you!!