@vs vs
in vec2 aPos;
in vec2 aTexCoords;

out vec2 TexCoords;

void main()
{
  gl_Position = vec4(aPos.x, aPos.y, 0.0, 1.0);
  TexCoords = aTexCoords;
}
@end

@fs fs
in vec2 TexCoords;
out vec4 frag_color;

uniform texture2D diffuse;
uniform sampler smp;
uniform mpara {
  uniform vec2 screensize;
};

void main()
{
  vec4 color = texture(sampler2D(diffuse,smp), TexCoords);
  float avg = 0.2126 * color.r + 0.7152 * color.g + 0.0722 * color.b;
  frag_color = vec4(avg,avg,avg,1.0);
  float lc = screensize.y/2.0;
  float line = TexCoords.y * lc;
  float line_intensity = mod(float(line),2);

  float off = line_intensity * 0.0005;
  vec4 shift = vec4(off,0,0,0);
  vec4 color_shift = vec4(0.001,0,0,0);
  float r = color.r + color_shift.r + shift.r;
  float g = color.g - color_shift.g + shift.g;
  float b = color.b;

  frag_color = vec4(r, g*0.99, b, 1.0) * clamp(line_intensity, 0.85, 1.0);

}
@end

@program crt vs fs