slang-shaders/crt/shaders/glow/gauss_horiz.slang

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#version 450
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
vec4 OutputSize;
vec4 OriginalSize;
vec4 SourceSize;
} global;
#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 float data_pix_no;
layout(location = 2) out float data_one;
void main()
{
gl_Position = global.MVP * Position;
vTexCoord = TexCoord;
data_pix_no = vTexCoord.x * global.SourceSize.x;
data_one = global.SourceSize.z;
}
#pragma stage fragment
#pragma format R8G8B8A8_SRGB
layout(location = 0) in vec2 vTexCoord;
layout(location = 1) in float data_pix_no;
layout(location = 2) in float data_one;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
#define INV_SQRT_2_PI 0.38 // Doesn't have to be accurate.
#define HORIZ_GAUSS_WIDTH 0.5
void main()
{
float texel = floor(data_pix_no);
float phase = data_pix_no - texel;
float base_phase = phase.x - 0.5;
vec2 tex = vec2((texel + 0.5) * global.SourceSize.z, vTexCoord.y);
vec3 col = vec3(0.0);
for (int i = -2; i <= 2; i++)
{
float phase = base_phase - float(i);
float g = INV_SQRT_2_PI * exp(-0.5 * phase * phase / (HORIZ_GAUSS_WIDTH * HORIZ_GAUSS_WIDTH)) / HORIZ_GAUSS_WIDTH;
col += texture(Source, tex + vec2(float(i) * data_one, 0.0)).rgb * g;
}
FragColor = vec4(col, 1.0);
}