#version 450

/*
   lcd1x-mix shader

   Modified from lcd1x (Gigaherz/jdgleaver, public domain) to add a
   GRID_STRENGTH mix parameter, letting the grid effect be blended
   with the unmodified image at any strength, independent of the
   BRIGHTEN_SCANLINES/BRIGHTEN_LCD ranges.
*/

#pragma parameter BRIGHTEN_SCANLINES "Brighten Scanlines" 16.0 1.0 32.0 0.5
#pragma parameter BRIGHTEN_LCD "Brighten LCD" 4.0 1.0 12.0 0.1
#pragma parameter GRID_STRENGTH "Grid Effect Strength" 1.0 0.0 1.0 0.05

layout(push_constant) uniform Push
{
   float BRIGHTEN_SCANLINES;
   float BRIGHTEN_LCD;
   float GRID_STRENGTH;
   vec4 OutputSize;
   vec4 OriginalSize;
   vec4 SourceSize;
} registers;

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;

#define PI 3.141592654

void main()
{
   vec2 pixelCoord = vTexCoord * registers.OriginalSize.xy;
   vec2 angle = 2.0 * PI * (pixelCoord - 0.25);

   float yfactor = (registers.BRIGHTEN_SCANLINES + sin(angle.y)) / (registers.BRIGHTEN_SCANLINES + 1.0);
   float xfactor = (registers.BRIGHTEN_LCD + sin(angle.x)) / (registers.BRIGHTEN_LCD + 1.0);

   vec3 colour = texture(Source, vTexCoord).rgb;
   vec3 gridded = yfactor * xfactor * colour;

   colour = mix(colour, gridded, registers.GRID_STRENGTH);

   FragColor = vec4(colour, 1.0);
}