Shader problems! GLSL Questions!

Hey everyone! So I have yet another question about shaders. Go figure! -__-

Anyways, this time, I was able to find a pretty slick looking shader online, which I was going to edit. The shader and page can be found here. Its pretty AWESOME! If someone can get this shader working in Unity (pro OR free.. I doubt it will work in free. Lol), OH MAN!

SO! I have the shader, but when I put it into Unity it doesn't work. Am I missing something? I don't need someone to rewrite it for me or anything, I just need some help. I do want to learn how to do these things as well. I also wanted to know if GLSL works in Unity. I have the shader below.

 uniform sampler2D ColorPass;
 uniform sampler2D BrushPass;
 uniform sampler2D DepthPass;
 
 varying vec2 vTexCoord;
 uniform float mode;
 
 void main (void)  
 {   
  vec3 brushValue; 
  vec3 bTex =  texture2D(BrushPass, vTexCoord).rgb;
 
  //Depth Values for current pixel and distored pixel
  //---------------------------------------------------------------------------------------------------
  
  float d_mag = 0.005;     //Magnitude of distortion
  
  //Apply 1.0 - smoothstep to depth values to map them to the visible 0-1 range
  //this is a fast and simple way to remap the depth buffer values
  
  //Get the depth value of the current pixel we're shading
  float depthVal = 1.0 - smoothstep( 0.998, 1.0, texture2D(DepthPass, vTexCoord).x);
  
  //Get the depth values of the neighbouring pixels in an x
 
       float depthVal_offset1    = 1.0 - smoothstep( 0.998, 1.0, texture2D(DepthPass, vTexCoord +  vec2( -d_mag, -d_mag)).x);
  float depthVal_offset2   = 1.0 - smoothstep( 0.998, 1.0, texture2D(DepthPass, vTexCoord + vec2(  d_mag, -d_mag)).x);
  float depthVal_offset3   = 1.0 - smoothstep( 0.998, 1.0, texture2D(DepthPass, vTexCoord + vec2( -d_mag,  d_mag)).x);
  float depthVal_offset4   = 1.0 - smoothstep( 0.998, 1.0, texture2D(DepthPass, vTexCoord + vec2(  d_mag,  d_mag)).x);
     
     //Find the difference between the neighbours' depth and our current pixel's depth
     float d_diff1 = depthVal_offset1 - depthVal;
     float d_diff2 = depthVal_offset2 - depthVal;
     float d_diff3 = depthVal_offset3 - depthVal;
     float d_diff4 = depthVal_offset4 - depthVal;
     
     //Find the maximum difference
     float depthMax = max( max( max( depthVal_offset4, depthVal_offset3 ), depthVal_offset2 ), depthVal_offset1 );
     
  vec3 color_offset;
 
  //Smudge more if object is distant, like DOF but painterly
  
  d_mag = 0.008*(1.0-1.5*depthVal);
  
  //Which neighbour has the maximum depth difference, 
  //get the color value from the opposite direction , and smudge
  //multiply the distort vector by the brush texture to get the paint bands.  
  
  if ( depthVal_offset4 == depthMax )
  {
   brushValue =  texture2D(BrushPass, vTexCoord - vec2(-d_mag,-d_mag) ).rgb; 
   color_offset = texture2D(ColorPass, vTexCoord + (-0.5+brushValue.r)*vec2( -d_mag, -d_mag)).rgb;
  }
  else if ( depthVal_offset3 == depthMax )
  {
   brushValue =  texture2D(BrushPass, vTexCoord - vec2( d_mag,-d_mag) ).rgb; 
   color_offset = texture2D(ColorPass, vTexCoord + (-0.5+brushValue.r)*vec2(  d_mag, -d_mag)).rgb;
   
  }
  else if ( depthVal_offset2 == depthMax )
  {
   brushValue =  texture2D(BrushPass, vTexCoord - vec2( -d_mag, d_mag) ).rgb; 
   color_offset = texture2D(ColorPass, vTexCoord + (-0.5+brushValue.r)*vec2(  -d_mag,  d_mag)).rgb;
  }
  else if ( depthVal_offset1  == depthMax )
  {
   brushValue =  texture2D(BrushPass, vTexCoord - vec2( d_mag, d_mag) ).rgb; 
   color_offset = texture2D(ColorPass, vTexCoord + (-0.5+brushValue.r)*vec2(  d_mag,  d_mag)).rgb;
  }
  
  //Bump ----------------------------------------------------------------------
 
   vec3 myLight = vec3(0.35,0.659,0.47);
   float bumpValue = 1.8*dot( myLight, vec3( bTex.r, bTex.r, bTex.r ) );
   bumpValue = clamp( bumpValue, 0.5, 1.0 );
  
  //------------------------------------------------------------------------------
  
  
  //Vignette --------------------------------------------------------------------
  
   float dist = distance(vTexCoord.xy, vec2(0.5,0.5));
   float a = smoothstep(0.9, 0.1, dist);
   float b = 0.4 *a;
  
  //------------------------------------------------------------------------------
  
  // Color Correction--Levelling ----------------------------------------------
  
   float mr = smoothstep( 0.0, (0.95), color_offset.r );
   float mg = smoothstep( 0.0, (0.95), color_offset.g );
   float mb = smoothstep( 0.0, (0.95), color_offset.b );
  
  //------------------------------------------------------------------------------
 
      vec4 FinalResult = vec4( a*(vec3(mr,mg,mb) - (0.1*bumpValue) + 0.05*vec3(bTex.r,bTex.r,bTex.r) ), (1.0-bTex.g));
  
   if ( mode == 1 )      //Normal Rendering
   gl_FragColor = FinalResult;
  
   if ( mode == 2 )      //Dimmed for menus
   gl_FragColor = vec4(  0.4*vec3(FinalResult.r ,  FinalResult.g,  FinalResult.b), 1.0);
   
  if ( mode == 3 )          //Red-ish for loosing health
   gl_FragColor = vec4(  FinalResult.r ,  FinalResult.g*0.25,  FinalResult.b*0.25, 1.0);
  
 }