#ifdef GL_ES
precision mediump int;
precision mediump float;
#endif

#define USE_OGRE_FROM_FUTURE
#include <OgreUnifiedShader.h>

SAMPLER2D(inRTT, 0);

OGRE_UNIFORMS(
uniform vec2 texelSize;
)

MAIN_PARAMETERS
IN(vec2 oUv0, TEXCOORD0)
MAIN_DECLARATION
{
  vec4 LUMINENCE_FACTOR = vec4(0.2125, 0.7154, 0.0721, 0.0);
  vec4 accum = vec4(0.0, 0.0, 0.0, 0.0);
  
  // Get colour from source
  accum += texture2D(inRTT, oUv0 + texelSize * vec2(-1.5, -1.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2(-0.5, -1.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2( 0.5, -1.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2( 1.5, -1.5));
  
  accum += texture2D(inRTT, oUv0 + texelSize * vec2(-1.5, -0.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2(-0.5, -0.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2( 0.5, -0.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2( 1.5, -0.5));
  
  accum += texture2D(inRTT, oUv0 + texelSize * vec2(-1.5, 0.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2(-0.5, 0.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2( 0.5, 0.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2( 1.5, 0.5));
  
  accum += texture2D(inRTT, oUv0 + texelSize * vec2(-1.5, 1.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2(-0.5, 1.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2( 0.5, 1.5));
  accum += texture2D(inRTT, oUv0 + texelSize * vec2( 1.5, 1.5));

  // Adjust the accumulated amount by lum factor
  float lum = dot(accum, LUMINENCE_FACTOR);
  
  // take average of 16 samples
  lum *= 0.0625;
  gl_FragColor = vec4(lum, lum, lum, 1.0);
}