/*
/   "Conditional Blending of Dither" Shader v1.0 - Pass 1
/   Copyright (c) 2013, Alexander Kulagin <coastkid3d@gmail.com>
/   All Rights reserved.
/ 
/   Redistribution and use in source and binary forms, with or without
/   modification, are permitted provided that the following conditions are met:
/ 
/     * Redistributions of source code must retain the above copyright notice,
/       this list of conditions and the following disclaimer.
/ 
/     * Redistributions in binary form must reproduce the above copyright
/       notice, this list of conditions and the following disclaimer in the
/       documentation and/or other materials provided with the distribution.
/ 
/   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
/   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
/   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
/   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
/   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
/   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
/   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
/   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
/   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
/   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
/   POSSIBILITY OF SUCH DAMAGE.
*/

//////////////////
// VERTEX_SHADER

void main_vertex
(
	float2 position : POSITION,
	float2 texCoord : TEXCOORD0,
	uniform float4x4 modelViewProj,
	out float4 oPosition : POSITION,
	out float2 otexCoord : TEXCOORD
)
{
	oPosition = mul(modelViewProj, float4(position, 0.0f, 1.0f));
	otexCoord = texCoord;
}

//////////////////
// FRAGMENT SHADER

struct output
{
	float4 color : COLOR;
};

struct input
{
	float2 video_size;
	float2 texture_size;
	float2 output_size;
};


float4 main_fragment(float2 texCoord : TEXCOORD0, uniform sampler2D tex0 : TEXUNIT0, uniform input IN): COLOR
{ 
  float2 uv = texCoord - (1.0f / IN.texture_size) * 0.25f;
  float2 uv_shift = (1.0f / IN.texture_size);
	float3 src = tex2D(tex0, uv).rgb;
 
  // Searching for the Vertical Dithering Zones
	float3 dither_v_zone = tex2D(tex0, uv + float2(uv_shift.x, 0)).rgb == tex2D(tex0, uv - float2(uv_shift.x, 0)).rgb;
  dither_v_zone = smoothstep(0.2f, 1.0f, dot(dither_v_zone, 0.33333f));
  
  // Searching for High Contrast "Safe" Zones 
  float3 safe_zone = abs(dot(tex2D(tex0, uv) - tex2D(tex0, uv - float2(uv_shift.x, 0)),0.3333f));
  safe_zone = safe_zone < 0.45f;
 
  // Horizontal Bluring by 1 pixel
  float3 blur_h = (tex2D(tex0, uv).rgb + tex2D(tex0, uv - float2(uv_shift.x, 0)).rgb) * 0.5f;
  
  // Final Blend between Source and Blur using Dithering Zone and Safe Zone
  float3 finalcolor = lerp(src, blur_h, dither_v_zone * safe_zone);
  
  return float4(finalcolor, 1.0f);
}