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why one minus vertex color (zero value) is zero?

Discussion in 'Shaders' started by bbsuuo, Nov 2, 2021.

  1. bbsuuo

    bbsuuo

    Joined:
    Jul 21, 2016
    Posts:
    16
    • hi ,I'm writing a UI shader and simulate photoshop effect
    ​
    the code like (IN.color is vertex color) :

    fixed4 frag(v2f IN) : SV_Target
    {
    float4 testColor = tex2D(_MainTex, IN.texcoord) * IN.color;
    return (1 - testColor.a);
    }

    and This seems to be working well , but when i set vertex color zero , i get zero output , why ??
     
    bbsuuo, Nov 2, 2021
    #1

  2. bbsuuo

    bbsuuo

    Joined:
    Jul 21, 2016
    Posts:
    16
    ok , I get the idea the image will ignore when color alpha zero object rendering, i use frame debugger confirmed, so this is an optimization
     
    bbsuuo, Nov 2, 2021
    #2