// Adapted from https://github.com/duducosmos/defisheye
// (then resize to 1568x1080)

#extension GL_ARB_texture_rectangle: enable

uniform sampler2DRect myTextureY;
uniform sampler2DRect myTextureU;
uniform sampler2DRect myTextureV;
uniform vec2 myResolution;
uniform float pts;

const vec2 half_pixel = vec2(0.5, 0.5);
const float pi = 3.1415927;

const float input_fov = 150.0 * pi / 720.0;
const float output_fov = 116.0 * pi / 360.0;

vec2 unfish(vec2 coord) {
    vec2 center = myResolution * 0.5;
    vec2 pos = coord - center;
    float rd = length(pos);
    float diameter = sqrt(dot(myResolution, myResolution));
    return center + pos * ((diameter / (2.0 * sin(input_fov))) * sin(atan(rd / (diameter / (2.0 * tan(output_fov)))) * 0.5) / rd);
}

void main() {
    vec2 y_coord = unfish(gl_TexCoord[0].xy + half_pixel);
    vec2 uv_coord = y_coord * 0.5;
    vec4 y = texture2DRect(myTextureY, y_coord);
    vec4 u = texture2DRect(myTextureU, uv_coord);
    vec4 v = texture2DRect(myTextureV, uv_coord);
    gl_FragColor = vec4(y.r, u.r, v.r, 1.0);
}