在片段着色器中使用相机根据距离修改颜色 Alpha (UNITY 3D)

Question

我有以下着色器代码：

Shader "Ogxd/Wireframe"
{
Properties
{
  _FadeDistance("Fade Distance", Float) = 3.0
  _EdgeColor("Edge Color", Color) = (0 ,0 ,0 ,1)
  _WireframeThickness("Thickness", Range(0.0, 3.0)) = 0.5
  [Toggle()] _FixedWidth("Relative to Screen", Float) = 0.0
  _WireframeSmoothing("Smoothing", Range(0.0, 3.0)) = 1.0
  [Toggle(_QUADIFY)] _Quadify("Quadify", Float) = 0.0
}

SubShader
{
  Tags { "Queue" = "Transparent" "RenderType" = "Transparent" "IgnoreProjector" = "True" }

  Pass
  {
     Name "Wireframe"

     Cull Back
     ZWrite On
     Blend SrcAlpha OneMinusSrcAlpha
     
     CGPROGRAM

     #pragma glsl
     #pragma vertex vert
     #pragma geometry geom
     #pragma fragment frag
     #pragma multi_compile __ _QUADIFY
     #include "UnityCG.cginc"

     struct appdata
     {
        float4 vertex : POSITION;
        float2 uv : TEXCOORD0;
     };

     struct v2g
     {
        float4 vertex : SV_POSITION;
     };

     struct g2f
     {
        float4 vertex : SV_POSITION;
        float3 bary : TEXCOORD1;
     };

     v2g vert(appdata v)
     {
        v2g o;
        o.vertex = mul(unity_ObjectToWorld, v.vertex);
        return o;
     }

     [maxvertexcount(3)]
     void geom(triangle v2g i[3], inout TriangleStream<g2f> triStream) {
        float3 param = float3(0.0, 0.0, 0.0);

 #ifdef _QUADIFY
        float A = length(i[0].vertex - i[1].vertex);
        float B = length(i[1].vertex - i[2].vertex);
        float C = length(i[2].vertex - i[0].vertex);

        if (A > B && A > C)
           param.y = 1.0;
        else if (B > C && B > A)
           param.x = 1.0;
        else
           param.z = 1.0;
#endif

        g2f o;
        o.vertex = mul(UNITY_MATRIX_VP, i[0].vertex);
        o.bary = float3(1.0, 0.0, 0.0) + param;
        triStream.Append(o);

        o.vertex = mul(UNITY_MATRIX_VP, i[1].vertex);
        o.bary = float3(0.0, 0.0, 1.0) + param;
        triStream.Append(o);

        o.vertex = mul(UNITY_MATRIX_VP, i[2].vertex);
        o.bary = float3(0.0, 1.0, 0.0) + param;
        triStream.Append(o);
     }

     float _WireframeThickness;
     float _WireframeSmoothing;
     float _FixedWidth;
     float _FadeDistance;
     float4 _EdgeColor;

     half4 frag(g2f i) : SV_Target
     {
        float3 bary = i.bary;
        float3 deltas = fwidth(bary);
        float3 smoothing = deltas * _WireframeSmoothing;
        float3 thickness = deltas * _WireframeThickness / max((1 - _FixedWidth) * i.vertex.w, _FixedWidth);
        bary = smoothstep(thickness, thickness + smoothing, bary);
        float t = min(bary.x, min(bary.y, bary.z));

        _EdgeColor.w = clamp(length(WorldSpaceViewDir(i.vertex)) - _FadeDistance, 0, 1);

        return half4(_EdgeColor.rgb, 1 - t);
     }
     ENDCG
  }
}

}

我最近添加了以下变量：

_FadeDistance

，试图在 frag 调用中为

_EdgeColor

的 Alpha 通道添加透明度。

但是相机方面没有任何反应。换句话说，我得到的是固定颜色，而不是具有不同 alpha 的颜色。有人可以帮忙吗？

谢谢！

Answer 1

shingo 给出了答案，并使用了其他已回答的堆栈溢出问题：Unity 距离淡入淡出着色器