slang-shaders/cubic/shaders/bicubic.slang
2020-07-16 16:12:18 -05:00

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#version 450
/*
Copyright (C) 2010 Team XBMC
http://www.xbmc.org
Copyright (C) 2011 Stefanos A.
http://www.opentk.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, 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 XBMC; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
http://www.gnu.org/copyleft/gpl.html
*/
layout(push_constant) uniform Push
{
vec4 SourceSize;
vec4 OriginalSize;
vec4 OutputSize;
uint FrameCount;
float B, C;
} params;
// Default to Mitchel-Netravali coefficients for best psychovisual result
// bicubic-sharp is B = 0.1 and C = 0.5
// bicubic-sharper is B = 0.0 and C = 0.75
#pragma parameter B "Bicubic Coeff B" 0.33 0.0 1.0 0.01
#pragma parameter C "Bicubic Coeff C" 0.33 0.0 1.0 0.01
#define B params.B
#define C params.C
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
} global;
#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;
void main()
{
gl_Position = global.MVP * Position;
vTexCoord = TexCoord;
}
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
float weight(float x)
{
float ax = abs(x);
if (ax < 1.0)
{
return
(
pow(x, 2.0) * ((12.0 - 9.0 * B - 6.0 * C) * ax + (-18.0 + 12.0 * B + 6.0 * C)) +
(6.0 - 2.0 * B)
) / 6.0;
}
else if ((ax >= 1.0) && (ax < 2.0))
{
return
(
pow(x, 2.0) * ((-B - 6.0 * C) * ax + (6.0 * B + 30.0 * C)) +
(-12.0 * B - 48.0 * C) * ax + (8.0 * B + 24.0 * C)
) / 6.0;
}
else
{
return 0.0;
}
}
vec4 weight4(float x)
{
return vec4(
weight(x - 2.0),
weight(x - 1.0),
weight(x),
weight(x + 1.0));
}
vec3 pixel(float xpos, float ypos, sampler2D tex)
{
return texture(tex, vec2(xpos, ypos)).rgb;
}
vec3 line_run(float ypos, vec4 xpos, vec4 linetaps, sampler2D tex)
{
return
pixel(xpos.r, ypos, tex) * linetaps.r +
pixel(xpos.g, ypos, tex) * linetaps.g +
pixel(xpos.b, ypos, tex) * linetaps.b +
pixel(xpos.a, ypos, tex) * linetaps.a;
}
void main()
{
vec2 stepxy = vec2(1.0/params.SourceSize.x, 1.0/params.SourceSize.y);
vec2 pos = vTexCoord.xy + stepxy * 0.5;
vec2 f = fract(pos / stepxy);
vec4 linetaps = weight4(1.0 - f.x);
vec4 columntaps = weight4(1.0 - f.y);
//make sure all taps added together is exactly 1.0, otherwise some (very small) distortion can occur
linetaps /= linetaps.r + linetaps.g + linetaps.b + linetaps.a;
columntaps /= columntaps.r + columntaps.g + columntaps.b + columntaps.a;
vec2 xystart = (-1.5 - f) * stepxy + pos;
vec4 xpos = vec4(xystart.x, xystart.x + stepxy.x, xystart.x + stepxy.x * 2.0, xystart.x + stepxy.x * 3.0);
// final sum and weight normalization
vec4 final = vec4(line_run(xystart.y , xpos, linetaps, Source) * columntaps.r +
line_run(xystart.y + stepxy.y , xpos, linetaps, Source) * columntaps.g +
line_run(xystart.y + stepxy.y * 2.0, xpos, linetaps, Source) * columntaps.b +
line_run(xystart.y + stepxy.y * 3.0, xpos, linetaps, Source) * columntaps.a,1);
FragColor = final;
}