rgbm.shader

// http://graphicrants.blogspot.com/2009/04/rgbm-color-encoding.html

float4 RGBMEncode( float3 color ) {
  float4 rgbm;
  color *= 1.0 / 6.0;
  rgbm.a = saturate( max( max( color.r, color.g ), max( color.b, 1e-6 ) ) );
  rgbm.a = ceil( rgbm.a * 255.0 ) / 255.0;
  rgbm.rgb = color / rgbm.a;
  return rgbm;
}

float3 RGBMDecode( float4 rgbm ) {
  return 6.0 * rgbm.rgb * rgbm.a;
}