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uniform sampler2D img;
uniform float stepx;
uniform float stepy;
//nvidia's half is a 16 bit float and can bring some speed improvements
//without affecting quality
#ifndef __GLSL_CG_DATA_TYPES
#define half float
#define half3 vec3
#define half4 vec4
#endif
#if (HAS_FLOAT_TEXTURE)
uniform sampler1D kernelTex;
half3 weight(float pos)
{
return texture1D(kernelTex, pos).rgb;
}
#else
uniform sampler2D kernelTex;
half3 weight(float pos)
{
//row 0 contains the high byte, row 1 contains the low byte
return ((texture2D(kernelTex, vec2(pos, 0.0)) * 256.0 + texture2D(kernelTex, vec2(pos, 1.0)))).rgb / 128.5 - 1.0;
}
#endif
half3 pixel(float xpos, float ypos)
{
return texture2D(img, vec2(xpos, ypos)).rgb;
}
half3 line (float ypos, vec3 xpos1, vec3 xpos2, half3 linetaps1, half3 linetaps2)
{
return
pixel(xpos1.r, ypos) * linetaps1.r +
pixel(xpos1.g, ypos) * linetaps2.r +
pixel(xpos1.b, ypos) * linetaps1.g +
pixel(xpos2.r, ypos) * linetaps2.g +
pixel(xpos2.g, ypos) * linetaps1.b +
pixel(xpos2.b, ypos) * linetaps2.b;
}
void main()
{
float xf = fract(gl_TexCoord[0].x / stepx);
float yf = fract(gl_TexCoord[0].y / stepy);
half3 linetaps1 = weight((1.0 - xf) / 2.0);
half3 linetaps2 = weight((1.0 - xf) / 2.0 + 0.5);
half3 columntaps1 = weight((1.0 - yf) / 2.0);
half3 columntaps2 = weight((1.0 - yf) / 2.0 + 0.5);
//make sure all taps added together is exactly 1.0, otherwise some (very small) distortion can occur
half sum = linetaps1.r + linetaps1.g + linetaps1.b + linetaps2.r + linetaps2.g + linetaps2.b;
linetaps1 /= sum;
linetaps2 /= sum;
sum = columntaps1.r + columntaps1.g + columntaps1.b + columntaps2.r + columntaps2.g + columntaps2.b;
columntaps1 /= sum;
columntaps2 /= sum;
float xstart = (-1.5 - xf) * stepx + gl_TexCoord[0].x;
vec3 xpos1 = vec3(xstart, xstart + stepx, xstart + stepx * 2.0);
xstart += stepx * 3.0;
vec3 xpos2 = vec3(xstart, xstart + stepx, xstart + stepx * 2.0);
float ystart = (-1.5 - yf) * stepy + gl_TexCoord[0].y;
gl_FragColor.rgb =
line(ystart , xpos1, xpos2, linetaps1, linetaps2) * columntaps1.r +
line(ystart + stepy , xpos1, xpos2, linetaps1, linetaps2) * columntaps2.r +
line(ystart + stepy * 2.0, xpos1, xpos2, linetaps1, linetaps2) * columntaps1.g +
line(ystart + stepy * 3.0, xpos1, xpos2, linetaps1, linetaps2) * columntaps2.g +
line(ystart + stepy * 4.0, xpos1, xpos2, linetaps1, linetaps2) * columntaps1.b +
line(ystart + stepy * 5.0, xpos1, xpos2, linetaps1, linetaps2) * columntaps2.b;
gl_FragColor.a = gl_Color.a;
}
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