Hatching Shader?

Does anyone know how to make a cross hatched shader like this one? http://learningwebgl.com/lessons/example04/teapot-simple-crosshatch.html

There is an attached GLSL shader but after trying to add it into Unity i get warnings about graphics card..

VERTEX SHADER:

   attribute vec3 aVertexPosition;
     attribute vec3 aVertexNormal;

     uniform mat4 uMVMatrix;
     uniform mat4 uPMatrix;
     uniform mat4 uNMatrix;

     varying vec4 vTransformedNormal;
     varying vec4 vPosition;


     void main(void) {
         vPosition = uMVMatrix * vec4(aVertexPosition, 1.0);
         gl_Position = uPMatrix * vPosition;
         vTransformedNormal = uNMatrix * vec4(aVertexNormal, 1.0);
     }

FRAGMENT SHADER:

 #ifdef GL_ES
     precision highp float;
     #endif

     varying vec4 vTransformedNormal;
     varying vec4 vPosition;

     uniform float uMaterialShininess;

     uniform vec3 uAmbientColor;

     uniform vec3 uPointLightingLocation;
     uniform vec3 uPointLightingSpecularColor;
     uniform vec3 uPointLightingDiffuseColor;

     uniform sampler2D uSampler;


     void main(void) {
         vec3 lightWeighting;
         vec3 lightDirection = normalize(uPointLightingLocation - vPosition.xyz);
         vec3 normal = normalize(vTransformedNormal.xyz);

         float specularLightWeighting = 0.0;
         vec3 eyeDirection = normalize(-vPosition.xyz);
         vec3 reflectionDirection = reflect(-lightDirection, normal);

         specularLightWeighting = pow(max(dot(reflectionDirection, eyeDirection), 0.0), uMaterialShininess);

         float diffuseLightWeighting = max(dot(normal, lightDirection), 0.0);
         lightWeighting = uAmbientColor
             + uPointLightingSpecularColor * specularLightWeighting
             + uPointLightingDiffuseColor * diffuseLightWeighting;

         gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
         if (length(lightWeighting) < 1.00) {
             if (mod(gl_FragCoord.x + gl_FragCoord.y, 10.0) == 0.0) {
                 gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
             }
         }
         if (length(lightWeighting) < 0.75) {
             if (mod(gl_FragCoord.x - gl_FragCoord.y, 10.0) == 0.0) {
                 gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
             }
         }
         if (length(lightWeighting) < 0.50) {
             if (mod(gl_FragCoord.x + gl_FragCoord.y - 5.0, 10.0) == 0.0) {
                 gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
             }
         }

         if (length(lightWeighting) < 0.3465) {
             if (mod(gl_FragCoord.x - gl_FragCoord.y - 5.0, 10.0) == 0.0) {
                 gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
             }
         }
     }