Pete`s Messageboard Forum - OGL2 shaders - Experimental 2x resize shader

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/*

Experimental 2x resize shader - fragment file (v0.001)

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

I'll try to code a shader which does some double image resizing.
9+ texels (box style) input, 4 result texels output, classic approach - so to say.

Since it's going to be a single pass shader, it'll do some bilinear interpolation afterwards.
The idea is borrowed from the Scale2xSaI algorithm from mr. Derek Liauw Kie Fa.

More patterns are to be added with time...

*/



const float p = 1.0; // "linear" Interpolation type


varying vec2 dx,dy,d1,d2;

uniform vec4 OGL2Size;
uniform sampler2D OGL2Texture;

void main()
{

// Calculating texel coordinates

vec2 OGL2Pos = gl_TexCoord[0].xy*OGL2Size.xy;
vec2 fp = fract(OGL2Pos);

vec2 d11 = floor(OGL2Pos)/OGL2Size.xy;
vec2 d00 = d11 - d1;
vec2 d10 = d11 - dy;
vec2 d20 = d11 - d2;
vec2 d01 = d11 - dx;
vec2 d21 = d11 + dx;
vec2 d02 = d11 + d2;
vec2 d12 = d11 + dy;
vec2 d22 = d11 + d1;


// Reading the texels

vec3 c00 = texture2D(OGL2Texture,d00).xyz;
vec3 c10 = texture2D(OGL2Texture,d10).xyz;
vec3 c20 = texture2D(OGL2Texture,d20).xyz;
vec3 c01 = texture2D(OGL2Texture,d01).xyz;
vec3 c11 = texture2D(OGL2Texture,d11).xyz;
vec3 c21 = texture2D(OGL2Texture,d21).xyz;
vec3 c02 = texture2D(OGL2Texture,d02).xyz;
vec3 c12 = texture2D(OGL2Texture,d12).xyz;
vec3 c22 = texture2D(OGL2Texture,d22).xyz;
vec3 dt = vec3(1.0,1.0,1.0);


// Calculating color differences

float f00 = dot(abs(c00-c11),dt);
float f10 = dot(abs(c10-c11),dt);
float f20 = dot(abs(c20-c11),dt);
float f01 = dot(abs(c01-c11),dt);
float f11 = dot(abs(c11-c11),dt);
float f21 = dot(abs(c21-c11),dt);
float f02 = dot(abs(c02-c11),dt);
float f12 = dot(abs(c12-c11),dt);
float f22 = dot(abs(c22-c11),dt);
float hrl = dot(abs(c01-c21),dt);
float vrl = dot(abs(c10-c12),dt);
float dg1 = dot(abs(c00-c22),dt);
float dg2 = dot(abs(c02-c20),dt);


// Calculating produtcs

vec3 p00,p10,p01,p11;

if ((f10==f21 && f01==f12 && f10!=f01) \|\| (f01==f10 && f12==f21 && f01!=f12))
{
p00 = (c01+c11+c10)/3.0;
p10 = (c21+c11+c10)/3.0;
p01 = (c01+c11+c12)/3.0;
p11 = (c12+c11+c21)/3.0;
}
else

if (max(f00,f22)==0.0 && f02!=f20)
{
p00 = c11;
p10 = (c21+c11+c10)/3.0;
p01 = (c01+c11+c12)/3.0;
p11 = c11;
}
else

if (max(f02,f20)==0.0 && f00!=f22)
{
p00 = (c01+c11+c10)/3.0;
p10 = c11;
p01 = c11;
p11 = (c12+c11+c21)/3.0;
}
else

{
p00 = c11;
p10 = c11;
p01 = c11;
p11 = c11;
}


// product interpolation

vec2 x = vec2(pow(1.0-fp.x,p),pow(fp.x,p));
vec2 y = vec2(pow(1.0-fp.y,p),pow(fp.y,p));

gl_FragColor.xyz = ((p00x.x+p10x.y)y.x+(p01x.x+p11x.y)y.y)/((x.x+x.y)*(y.x+y.y));

}

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Experimental 2x resize shader

Experimental 2x resize shader