#version 450 core

#pragma include ./shared.glsl
#pragma include ../../misc/camera.glsl

in FragmentData fragmentData;

uniform vec2 uRings;
uniform vec2 uMarker;
uniform float uProgress;
uniform float uSize;
uniform float uValue;

out vec4 outColor;

const float RING_STRENGTH   = 0.0000;
const float RING_BLUR       = 0.0020;
const float MARKER_STRENGTH = 0.0000;
const float MARKER_BLUR     = 0.0020;
const vec2  VEC_HORZ        = vec2(1.0, 0.0);
const float PI              = 3.1415926535897932384626433832795;

float smoothstep2(float b0, float b1, float b2, float b3, float v) {
    return smoothstep(b0, b1, v) * (1.0 - smoothstep(b2, b3, v));
}

float calcLine(float actual, float expected, float strength, float blur)
{
    return smoothstep2(
        expected - strength - blur,
        expected - strength,
        expected + strength,
        expected + strength + blur,
        actual);
}

float calcAngle(vec2 v1, vec2 v2)
{
    v1 = -v1;
    return -atan(
        v1.x * v2.y - v1.y * v2.x,
        v1.x * v2.x + v1.y * v2.y);
}

float random(float seed) {
    return fract(sin(dot(vec4(seed), vec4(12.9898, 78.233, 45.164, 53.1324))) * 43758.5453);
}

float animate(float v0, float v1, float t) {
    float x = t * t * (3.0 - 2.0 * t);

    return v0 + x * (v1 - v0);
}

void main() {
    float ts = clamp(uProgress, 0.0, 1.0);
    float te = clamp(uProgress - 1.0, 0.0, 1.0);
    float r = length(fragmentData.texCoords);
    float zoom = pow(length(uCamera.view[0].xyz), 0.5);
    float angle = calcAngle(fragmentData.texCoords, VEC_HORZ);

    /* marker */
    float m = calcAngle(uMarker, VEC_HORZ);
    m = calcLine(angle, m, MARKER_STRENGTH / r / zoom, MARKER_BLUR / r / zoom);
    m *= smoothstep2(
        ts * (uRings[0] - 0.25),
        ts *  uRings[0],
        ts *  uRings[1],
        ts * (uRings[1] + 0.10),
        r);
    m *= 0.75;

    /* rings */
    float f = angle / PI + 1.0;
    f = f * 2.0;
    f = fract(f + 0.5);
    f = smoothstep2(
        0.0 - (ts - 0.5),
        0.2 - (ts - 0.5),
        0.8 + (ts - 0.5),
        1.0 + (ts - 0.5),
        f);

    float r0 = 0.25 * f * calcLine(r, animate(uSize, uRings[0], ts), RING_STRENGTH / zoom, RING_BLUR / zoom);
    float r1 = 0.25 * f * calcLine(r, animate(uSize, uRings[1], ts), RING_STRENGTH / zoom, RING_BLUR / zoom);
    float v  = 0.75 * f * calcLine(r, animate(uSize, uValue,    ts), RING_STRENGTH / zoom, RING_BLUR / zoom);

    /* alpha */
    float as = step(1.0 - ts, random(uProgress));
    float ae = (1.0 - te) * step(te, random(uProgress));
    float a = as * ae;

    /* put together */
    vec3 rgb = vec3(1.0);
    outColor = vec4(rgb, (v + r0 + r1 + m) * a + uSize * 0.0001);
}