#define PI 3.141592653589793

float sdEllipse(vec2 p, vec2 r) {
    vec2 q = p / r;
    return (length(q) - 1.0) * min(r.x, r.y);
}

float sdCircle(vec2 p, float r) {
    return length(p) - r;
}

float sdBox(vec2 p, vec2 b) {
    vec2 d = abs(p) - b;
    return length(max(d, 0.0)) + min(max(d.x, d.y), 0.0);
}

float opStroke(float d, float w) {
    return abs(d) - w;
}

float fill(float d) {
    return 1.0 - smoothstep(0.0, 0.004, d);
}

float stroke(float d, float w) {
    return 1.0 - smoothstep(0.0, 0.004, opStroke(d, w));
}

// Simple dollar sign SDF-ish shape
float dollarSign(vec2 p) {
    float s = 0.0;

    // main vertical bar
    float bar = fill(sdBox(p, vec2(0.018, 0.18)));

    // upper curve
    vec2 pu = p - vec2(0.02, 0.07);
    float upperOuter = stroke(sdCircle(pu, 0.11), 0.020);
    float upperCut = fill(sdBox(pu - vec2(-0.07, 0.00), vec2(0.08, 0.14)));
    float upper = upperOuter * (1.0 - upperCut);

    // lower curve
    vec2 pl = p - vec2(-0.02, -0.07);
    float lowerOuter = stroke(sdCircle(pl, 0.11), 0.020);
    float lowerCut = fill(sdBox(pl - vec2(0.07, 0.00), vec2(0.08, 0.14)));
    float lower = lowerOuter * (1.0 - lowerCut);

    s = max(bar, max(upper, lower));
    return s;
}

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 uv = fragCoord.xy / iResolution.xy;
    vec4 base = texture(iChannel0, uv);
    vec3 col = base.rgb;

    // ------------------------------------------------------------------
    // Bouncing "DVD logo" style motion
    // ------------------------------------------------------------------
    vec2 logoSize = vec2(0.23, 0.13); // width/height of medallion in UV space
    vec2 minP = logoSize * 0.5 + vec2(0.03, 0.04);
    vec2 maxP = vec2(1.0) - minP;

    // Ping-pong motion
    vec2 travel = maxP - minP;
    vec2 phase = fract(vec2(iTime * 0.070, iTime * 0.052) + vec2(0.17, 0.61));
    vec2 tri = abs(phase * 2.0 - 1.0);
    vec2 center = minP + travel * tri;

    // Local coordinates around logo center
    vec2 p = uv - center;
    p.x *= iResolution.x / iResolution.y; // aspect correction

    // ------------------------------------------------------------------
    // Cash Money inspired medallion
    // ------------------------------------------------------------------
    float outer = sdEllipse(p, vec2(0.17, 0.095));
    float inner = sdEllipse(p, vec2(0.145, 0.078));
    float core  = sdEllipse(p, vec2(0.122, 0.060));

    float outerFill = fill(outer);
    float innerRing = stroke(inner, 0.010);
    float coreFill  = fill(core);

    // Rim beading / jewelry vibe
    float angle = atan(p.y, p.x);
    float beads = pow(0.5 + 0.5 * sin(angle * 26.0 - iTime * 2.2), 8.0);
    beads *= stroke(sdEllipse(p, vec2(0.158, 0.086)), 0.008);

    // Chrome/gold light sweep
    float sweep = pow(max(0.0, sin((uv.x * 4.0 + uv.y * 2.6) * PI * 2.0 - iTime * 1.7)), 18.0);

    vec3 darkGold = vec3(0.28, 0.12, 0.02);
    vec3 gold     = vec3(0.95, 0.67, 0.16);
    vec3 paleGold = vec3(1.00, 0.88, 0.52);
    vec3 diamond  = vec3(1.00, 0.96, 0.85);

    vec3 logoCol = vec3(0.0);

    // outer medallion
    logoCol += outerFill * mix(darkGold, gold, 0.65);
    logoCol += innerRing * paleGold * 0.9;
    logoCol += beads * paleGold * 0.8;
    logoCol += coreFill * mix(gold, paleGold, 0.35);

    // embossed center
    float emboss = 0.5 + 0.5 * sin(p.x * 28.0 + p.y * 12.0 - iTime * 0.6);
    logoCol += coreFill * emboss * vec3(0.10, 0.05, 0.01);

    // dollar sign centerpiece
    float ds = dollarSign(p * 1.7);
    logoCol = mix(logoCol, diamond, ds * 0.9);
    logoCol += ds * paleGold * 0.35;

    // little sparkle hits
    float sparkle1 = exp(-length((p - vec2(-0.07, 0.03)) * vec2(1.0, 1.2)) * 60.0);
    float sparkle2 = exp(-length((p - vec2(0.08, -0.01)) * vec2(1.0, 1.2)) * 80.0);
    float cross1 = (1.0 - smoothstep(0.0, 0.004, abs(p.x + 0.07))) * (1.0 - smoothstep(0.0, 0.05, abs(p.y - 0.03)));
    cross1 += (1.0 - smoothstep(0.0, 0.004, abs(p.y - 0.03))) * (1.0 - smoothstep(0.0, 0.05, abs(p.x + 0.07)));
    float cross2 = (1.0 - smoothstep(0.0, 0.003, abs(p.x - 0.08))) * (1.0 - smoothstep(0.0, 0.04, abs(p.y + 0.01)));
    cross2 += (1.0 - smoothstep(0.0, 0.003, abs(p.y + 0.01))) * (1.0 - smoothstep(0.0, 0.04, abs(p.x - 0.08)));

    float twinkle = 0.65 + 0.35 * sin(iTime * 5.0);
    logoCol += (sparkle1 * cross1 + sparkle2 * cross2) * paleGold * twinkle * 0.9;

    // moving light sweep across logo
    logoCol += outerFill * sweep * vec3(1.0, 0.92, 0.60) * 0.45;

    // subtle shadow behind logo
    float shadow = fill(sdEllipse(p - vec2(0.010, -0.010), vec2(0.17, 0.095)));
    shadow *= 0.18;

    // Logo mask
    float logoMask = outerFill;

    // Keep it in background so text stays readable
    // Darken behind medallion slightly, then add logo
    col = mix(col, col * 0.82, shadow);
    col = mix(col, col + logoCol, logoMask * 0.32);

    fragColor = vec4(clamp(col, 0.0, 1.0), base.a);
}