Custom shader : basic transparency on a mesh renderer

Graphics Shaders & Materials
1

Hello fellow unity developers.
I’ve already ask this question in the “Answers” section, but I haven’t got any solution.

My question is simple : how to make a custom shader displaying some transparency on a mesh renderer ?
I’m a programmer but not a shader artist and I’m really struggling with this simple task.

The following shader is used on a quad (with a mesh filter and a mesh renderer).
By varying the DisplayValue between 0.0 and 1.0, it should display a green gauge on transparent background.

Shader "Custom/Gauge" {
  
        Properties {
            DisplayValue ("Value", Float) = 0
        }
  
        SubShader {
            Tags { "RenderType" = "Transparent" "Queue" = "Transparent" }
  
            Pass {
                CGPROGRAM
                #pragma target 3.0
                #pragma vertex vert_img
                #pragma fragment frag
                #include "UnityCG.cginc"
  
                uniform float DisplayValue;
  
                float4 frag(v2f_img input) : COLOR {
  
                    if (input.uv.x < DisplayValue)
                    {
                        return half4(0.0, 1.0, 0.0, 1.0);
                    }
                    else
                    {
                        return half4(0.0, 0.0, 0.0, 0.0);
                    }
  
                }
              
                ENDCG
            }
        }
    }

But it display a green gauge on a black background, as if the return value in the else statement was half4(0,0,0,1) instread of half4(0,0,0,0).

Any idea about why it doesn’t work has I wish it to ? What I’m doing wrong ?

PS : Please forgive my mistakes, english is not my native language.

2

You must provide a blend mode for the shader to use like so…

Tags { "Queue"="Transparent"  "RenderType"="Transparent" }
Blend SrcAlpha OneMinusSrcAlpha
3

Yeees ! Thank you. It works perfectly now. That was exactly the missing element.