/*

   Copyright (C) 2007 guest(r) - guest.r@gmail.com

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

/*

   The 2xSaL shader processes a gfx. surface and redraws it 2x finer.
   
   A linear post-resize can fit the image to any resolution.

   Note: set scaler to normal2x.

*/

/* Default Vertex shader */
void main_vertex
(
 float4 position	: POSITION,
 float4 color	: COLOR,
 float2 texCoord : TEXCOORD0,

 uniform float4x4 modelViewProj,

 out float4 oPosition : POSITION,
 out float4 oColor    : COLOR,
 out float2 otexCoord : TEXCOORD
 )
{
   oPosition = mul(modelViewProj, position);
   oColor = color;
   otexCoord = texCoord;
}

struct output
{
   float4 color : COLOR;
};

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

struct deltas
{
   float2 UL, UR, DL, DR;
};

float3 quad_inter(float3 x0, float3 x1, float3 x2, float x)
{
   float3 poly[3];
   poly[2] = 0.5*x0 - x1 + 0.5*x2;
   poly[1] = -1.5*x0 + 2.0*x1 - 0.5*x2;
   poly[0] = x0;
   return poly[2] * x * x + poly[1] * x + poly[0];
}

output main_fragment (float2 tex : TEXCOORD0, uniform input IN, uniform sampler2D s0 : TEXUNIT0)
{
   float2 texsize = IN.texture_size;
   float vid_height = IN.output_size.y;
   float dx = float(pow(2.0 * texsize.x, -1.0));
   float dy = float(pow(2.0 * texsize.y, -1.0));

   float3 c01 = tex2D(s0, tex + float2(-dx, 0)).xyz;
   float3 c10 = tex2D(s0, tex + float2(0, -dy)).xyz;
   float3 c11 = tex2D(s0, tex + float2(0, 0)).xyz;
   float3 c12 = tex2D(s0, tex + float2(0, dy)).xyz;
   float3 c21 = tex2D(s0, tex + float2(dx, 0)).xyz;

   float3 xval0 = quad_inter(c01, c11, c21, tex.x * texsize.x - floor(tex.x * texsize.x) + 1.0);
   float3 yval0 = quad_inter(c10, c11, c12, tex.y * texsize.y - floor(tex.y * texsize.y) + 1.0);

   output OUT;
   //float scanline_mod = 1.0 - 0.1 * floor(fmod(vid_height * tex.y, 2.0));
   float scanline_mod = 1.0;

   OUT.color = float4(lerp(xval0, yval0, 0.5), 1.0) * scanline_mod;
   return OUT;
}