#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 accum = vec4(0.0, 0.0, 0.0, 0.0);
  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));
  
	// take average of 16 samples
	accum *= vec4_splat(0.0625);
  
  // Divide the sum to complete the average, and perform an exp() to complete
  // the average luminance calculation
  // min / max white
  gl_FragColor = vec4(clamp(accum.rgb, vec3_splat(0.4), vec3_splat(0.7)), 1.0);
}