glsl pbr encode in ycog gbuffer for deffered

pbd_deferred_ycog

vec4 encodeGBuffer(const in gBufferComponents components, const in vec2 texCoords, const in vec2 resolution, const in float clipFar) {
  vec4 res;
  vec3 diffuseYcocg = rgbToYcocg(components.diffuse);
  vec2 diffuseYc = getCheckerboard(texCoords, resolution) > 0.0 ? diffuseYcocg.xy : diffuseYcocg.xz;
  diffuseYc.y += 0.5;
  //Divide by clip far * 2.0 to sneak distance into a 0 to 1 range
  float depth = components.depth / (clipFar*2.0);
  //Scale normal from -1 to 1 to 0 to 1 range
  vec3 normal = components.normal * 0.5 + 0.5;
  //Scale down float components to 0 to 0.5
  res = vec4(normal, depth) * 0.5;
  res.xyz += floor(vec3(diffuseYc, components.gloss) * 255.0);
  res.w *= components.metallic;
  return res;
}

gBufferComponents decodeGBuffer(const in sampler2D gBufferSampler, 
                                const in vec2 texCoords, 
                                const in vec2 resolution, 
                                const in float clipFar)
{
  gBufferComponents res;
  vec4 encodedGBuffer  = texture2D(gBufferSampler, texCoords).rgba;
  vec3 floatComponents = fract(encodedGBuffer.xyz) * 2.0;
  res.normal   = floatComponents.xyz * 2.0 - 1.0;
  res.depth    = abs(encodedGBuffer.w) * 4.0 * clipFar;
  res.metallic = sign(encodedGBuffer.w);
  const float byteToFloat = 1.0/255.0;
  vec3 byteComponents = floor(encodedGBuffer.xyz) * byteToFloat;
  res.gloss = byteComponents.z;
  vec3 diffuseYcocg;
  diffuseYcocg.x = byteComponents.x;
  float pixelOffsetCoordsX = 1.0 / resolution.x;
  float offsetDir = getCheckerboard(texCoords, resolution);
  vec2 diffuseChroma;
  diffuseChroma.x = byteComponents.y - 0.5;
  diffuseChroma.y = texture2D(gBufferSampler, texCoords + vec2(pixelOffsetCoordsX*offsetDir, 0.0)).y;
  diffuseChroma.y = floor(diffuseChroma.y) * byteToFloat - 0.5;
  diffuseYcocg.yz = offsetDir > 0.0 ? diffuseChroma.xy : diffuseChroma.yx;
  res.diffuse = ycocgToRgb(diffuseYcocg);
  return res;
}

http://floored.com/blog/2014/webgl-deferred-shading-gbuffer-floating-point-texture.html