How to Use the Barymetric Wireframe Shader

I've tested the following shader in Unity 4. It will draw a correct wireframe on the standard Unity objects like cubes and planes. Since it draws lines where the texture coordinates are near 0 or 1, it wouldn't give you the desired result when applied to more complex meshes, but unlike the other solutions offered, it will at least work in simple cases. =)

 Shader "Custom/WireFrame"
 {
  Properties
  {
    _LineColor ("Line Color", Color) = (1,1,1,1)
    _GridColor ("Grid Color", Color) = (1,1,1,0)
    _LineWidth ("Line Width", float) = 0.2
  }
  SubShader
  {
    Pass
    {
      Tags { "RenderType" = "Transparent" }
      Blend SrcAlpha OneMinusSrcAlpha
      AlphaTest Greater 0.5
 
      CGPROGRAM
      #pragma vertex vert
      #pragma fragment frag
 
      uniform float4 _LineColor;
      uniform float4 _GridColor;
      uniform float _LineWidth;
 
      // vertex input: position, uv1, uv2
      struct appdata
      {
        float4 vertex : POSITION;
        float4 texcoord1 : TEXCOORD0;
        float4 color : COLOR;
      };
 
      struct v2f
      {
        float4 pos : POSITION;
        float4 texcoord1 : TEXCOORD0;
        float4 color : COLOR;
      };
 
      v2f vert (appdata v)
      {
        v2f o;
        o.pos = mul( UNITY_MATRIX_MVP, v.vertex);
        o.texcoord1 = v.texcoord1;
        o.color = v.color;
        return o;
      }
 
      fixed4 frag(v2f i) : COLOR
      {
        fixed4 answer;
 
        float lx = step(_LineWidth, i.texcoord1.x);
        float ly = step(_LineWidth, i.texcoord1.y);
        float hx = step(i.texcoord1.x, 1.0 - _LineWidth);
        float hy = step(i.texcoord1.y, 1.0 - _LineWidth);
 
        answer = lerp(_LineColor, _GridColor, lx*ly*hx*hy);
 
        return answer;
      }
      ENDCG
     }
  } 
  Fallback "Vertex Colored", 1
 }

this shader works fine with little fixes (below is full shader)

is just used second UV to draw grid. second UV can be done in rather any 3d modelling app and even in unity programmatically. attach it to primitives like plane or cube to see how it works

Shader "BarycentricWireframeUv1" { Properties { _LineColor ("Line Color", Color) = (1,1,1,1) _GridColor ("Grid Color", Color) = (0,0,0,0) _LineWidth ("Line Width", float) = 0.1 } SubShader { Pass { CGPROGRAM #pragma vertex vert #pragma fragment frag

uniform float4 _LineColor; uniform float4 _GridColor; uniform float _LineWidth;

// vertex input: position, uv1, uv2 struct appdata { float4 vertex : POSITION; float4 texcoord1 : TEXCOORD1; float4 color : COLOR; };

struct v2f { float4 pos : POSITION; float4 texcoord1 : TEXCOORD1; float4 color : COLOR; };

v2f vert (appdata v) { v2f o; o.pos = mul( UNITY_MATRIX_MVP, v.vertex); o.texcoord1 = v.texcoord1; o.color = v.color; return o; }

fixed4 frag(v2f i) : COLOR { fixed4 answer; if (i.texcoord1.x < _LineWidth || i.texcoord1.y < _LineWidth) { answer = _LineColor; } else if ((i.texcoord1.x - i.texcoord1.y) < _LineWidth && (i.texcoord1.y - i.texcoord1.x) < _LineWidth) { answer = _LineColor; } else { answer = _GridColor; } return answer; } ENDCG } } Fallback "Vertex Colored", 1 }