slang-shaders/handheld/shaders/gameboy/shader-files/gb-pass2.slang

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#version 450
layout(push_constant) uniform Push
{
vec4 OutputSize;
vec4 OriginalSize;
vec4 SourceSize;
} registers;
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layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
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} global;
///////////////////////////////////////////////////////////////////////////
// //
// Gameboy Classic Shader v0.2.2 //
// //
// Copyright (C) 2013 Harlequin : unknown92835@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 3 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, see <http://www.gnu.org/licenses/>. //
// //
///////////////////////////////////////////////////////////////////////////
#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;
layout(location = 1) out vec2 texel;
layout(location = 2) out vec2 lower_bound;
layout(location = 3) out vec2 upper_bound;
void main()
{
gl_Position = global.MVP * Position;
vTexCoord = TexCoord;
texel = registers.SourceSize.zw;
lower_bound = vec2(0.0);
upper_bound = vec2(texel * (registers.OutputSize.xy - 1.0));
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}
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 1) in vec2 texel;
layout(location = 2) in vec2 lower_bound;
layout(location = 3) in vec2 upper_bound;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
/*
sigma = 4.0, normalized for 5 pixel offset sigma = 4.0, normalized for 4 pixel offset
Raw Gaussian weights: Raw Gaussian weights:
0.09973561222190091607086808117254 @position0 0.09973561222190091607086808117254 @position0
0.09666707205829167156101677393475 @position1 0.09666707205829167156101677393475 @position1
0.08801637626376240452162358324964 @position2 0.08801637626376240452162358324964 @position2
0.07528440407628116669052257071979 @position3 0.07528440407628116669052257071979 @position3
0.06049272702308815188099267447364 @position4 0.06049272702308815188099267447364 @position4
0.04566231462789672460813692086928 @position5
sum [p0 + 2(p1 + p2 + p3 + p4 + p5)]: sum [p0 + 2(p1 + p2 + p3 + p4)]:
0.83198140032054115459545312766674 0.74065677106474770537917928592818
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Normalizing factor [1 / sum]: Normalizing factor [1 / sum]:
1.2019499469756482251051310195171 1.350153052084338115052273748029
Normalized Gaussian weights: Normalized Gaussian weights:
0.11987721382169761913280166382392 @position0 0.13465834124289953661305802732548 @position0
0.11618898213475484076479592086597 @position1 0.13051534237555914090930704141833 @position1
0.10579127878321792515352079488329 @position2 0.11883557904592230273554609080014 @position2
0.09048808548757942339961181362524 @position3 0.10164546793794160274995705611009 @position3
0.07270923003781316665844409497651 @position4 0.08167444001912718529866079800870 @position4
0.05488381664578583445722654373702 @position5
*/
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void main()
{
// Define offsets and weights - change this for both the X and Y passes if you change the sigma value or number of texels sampled
float offsets[5] = float[](0.0, 1.0, 2.0, 3.0, 4.0);
/*
Precalculated using the Gaussian function:
G(x) = (1 / sqrt(2 * pi * sigma^2)) * e^(-x^2 / (2 * sigma^2))
Where sigma = 4.0 and x = offset in range [0, 5]
Normalized to 1 to prevent image darkening by multiplying each weight by:
1 / sum(all weights)
*/
float weights[5] = float[]( 0.13465834124289953661305802732548,
0.13051534237555914090930704141833,
0.11883557904592230273554609080014,
0.10164546793794160274995705611009,
0.08167444001912718529866079800870 );
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// Sample the current fragment and apply its weight
vec4 out_color = texture(Source, clamp(vTexCoord, lower_bound, upper_bound)) * weights[0];
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// Iterate across the offsets in both directions sampling texels
// and adding their weighted alpha values to the total
for (int i = 1; i < 5; i++)
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{
out_color.a += texture(Source, clamp(vTexCoord + vec2(offsets[i] * texel.x, 0.0), lower_bound, upper_bound)).a * weights[i];
out_color.a += texture(Source, clamp(vTexCoord - vec2(offsets[i] * texel.x, 0.0), lower_bound, upper_bound)).a * weights[i];
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}
FragColor = out_color;
}