desc:GFX Gate
// gfx-gate - Analogue-Modelled Gate / Expander / Ducker with Keyed Sidechain & MIDI Trigger
//tags: gate expander ducker dynamics sidechain midi
//author: JGWizrad / Garden FX (GFX)
//
// MODEL     GATE  - comparator + VCA: the key opens the gate fully, closing drops by RANGE.
//                   SOFT knee lets the gate part-open over the 12 dB below THRESHOLD.
//           EXP   - downward expander: below THRESHOLD the gain falls at RATIO (1:2 = 1 dB under
//                   threshold -> 2 dB out), limited to RANGE. SOFT = 10 dB quadratic knee.
// FUNCTION  NORM  - classic gating / expansion.
//           DUCK  - the same curve flipped: key above threshold pulls the signal DOWN by RANGE.
// ANALOGUE  The control voltage is smoothed in dB like a log VCA: an RC on the control line,
//           so opening is fast then settles, and the release is a natural exponential fade
//           (times given ~ to 95%). The key goes through a peak rectifier with a 15 ms bleed.
// HOLD      keeps the gate open after the key falls below the close threshold.
// HYSTERESIS  opens at THRESHOLD, closes at THRESHOLD - HYST (no chatter on decaying notes).
// LOOKAHEAD  0 - 10 ms. 0 = zero latency; anything else is reported to REAPER as PDC.
//
// KEY       INT = the input itself, EXT = track channels 3/4 (route a send into 3/4).
//           HPF / LPF / FOCUS (bell) filter the key only - multi-band key shaping.
//           LISTEN plays the filtered key so you can tune the filters.
// STEREO    LINK  - one detector (louder channel) drives both sides.
//           DUAL  - independent L / R gates; LINK % pulls each detector toward the louder side.
//           M/S   - independent Mid / Side gates (key also in M/S); LINK % as above.
// MIDI      when MIDI is on, held notes force the gate open (or the duck down):
//           channel 1 = both sides, channel 2 = left (mid), channel 3 = right (side).
//           Set THRESHOLD to 0 dB for MIDI-only triggering. MIDI is passed through.
//
// GUI: drag knobs (Shift = fine), double-click / Ctrl-click = reset. Click the LCD for the
// preset list. SIZE S / M / L sets the panel size (60 / 75 / 90%; smaller if the window is smaller).

slider1:0<0,15,1{Init,Kick Tight,Snare Crack,Tom Cleanup,Hi-Hat Clean,Vocal Breath,Guitar Noise,Bass DI,Gentle Expander,Room Mic Tame,Dialogue Clean,Kick Duck (Ext Key),Voice-Over Duck (Ext Key),Gated Reverb 80s,MIDI Chop,Lookahead Drum}>-Preset
slider2:0<0,1,1{Gate,Expander}>-Model
slider3:0<0,1,1{Normal,Duck}>-Function
slider4:0<0,1,1{Hard,Soft}>-Knee
slider5:-40<-80,0,0.1>-Threshold (dB)
slider6:60<0,80,0.1>-Range (dB)
slider7:2<1,10,0.1>-Ratio
slider8:0.5<0.01,100,0.01>-Attack (ms)
slider9:50<0,2000,1>-Hold (ms)
slider10:150<5,4000,1>-Release (ms)
slider11:4<0,20,0.1>-Hysteresis (dB)
slider12:0<0,10,0.1>-Lookahead (ms)
slider13:0<0,1,1{Internal,External 3/4}>-Key Source
slider14:0<0,1,1{Off,On}>-MIDI Trigger
slider15:0<0,2,1{Linked,Dual Mono,Mid/Side}>-Stereo
slider16:100<0,100,1>-Link (%)
slider17:20<20,5000,1>-Key HPF (Hz)
slider18:20000<100,20000,1>-Key LPF (Hz)
slider19:1000<100,10000,1>-Key Focus (Hz)
slider20:0<-12,12,0.1>-Key Focus Gain (dB)
slider21:0<0,1,1{Off,On}>-Key Listen
slider22:100<0,100,1>-Mix (%)
slider23:0<-24,12,0.1>-Output (dB)

in_pin:Left
in_pin:Right
in_pin:Key Left
in_pin:Key Right
out_pin:Left
out_pin:Right

@init
// =====================================================================
// Helpers
// =====================================================================
nextmem = 0;
function alloc(n) local(p) ( p = nextmem; nextmem += n; p; );
function db2g(d) ( exp(d*0.11512925465); );
function g2db(g) ( 8.68588963807*log(max(g, 0.00000001)); );      // floor -160 dB
function cms(t) ( 1 - exp(-1/(max(0.000001, t)*srate)); );
function softk(o, w) ( o <= -w*0.5 ? 0 : o >= w*0.5 ? o : (o + w*0.5)*(o + w*0.5)/(2*w); );
function smst(v) ( v = max(0, min(1, v)); v*v*(3 - 2*v); );

// Biquad DF1: c = [b0 b1 b2 a1 a2], s = [x1 x2 y1 y2]
function bqf(x, c, s) local(y) (
  y = c[0]*x + c[1]*s[0] + c[2]*s[1] - c[3]*s[2] - c[4]*s[3];
  s[1] = s[0]; s[0] = x; s[3] = s[2]; s[2] = y;
  y;
);
function cLP(c, f, q) local(w, cs, al, a0) (
  w = 2*$pi*min(f, srate*0.45)/srate; cs = cos(w); al = sin(w)/(2*q); a0 = 1 + al;
  c[0] = (1 - cs)*0.5/a0; c[1] = (1 - cs)/a0; c[2] = c[0]; c[3] = -2*cs/a0; c[4] = (1 - al)/a0;
);
function cHP(c, f, q) local(w, cs, al, a0) (
  w = 2*$pi*min(f, srate*0.45)/srate; cs = cos(w); al = sin(w)/(2*q); a0 = 1 + al;
  c[0] = (1 + cs)*0.5/a0; c[1] = -(1 + cs)/a0; c[2] = c[0]; c[3] = -2*cs/a0; c[4] = (1 - al)/a0;
);
function cPK(c, f, g, q) local(A, w, cs, al, a0) (
  A = 10^(g/40); w = 2*$pi*min(f, srate*0.45)/srate; cs = cos(w); al = sin(w)/(2*q); a0 = 1 + al/A;
  c[0] = (1 + al*A)/a0; c[1] = -2*cs/a0; c[2] = (1 - al*A)/a0; c[3] = -2*cs/a0; c[4] = (1 - al/A)/a0;
);

// ---- static gain computer: key level L (dB), open flag -> target gain (dB, <= 0) ----
// Used by the DSP and by the GUI transfer curve.
function tgain(L, op) local(g, te, b) (
  mdl == 0 ? (
    g = op ? 0 : (knee ? -rngDb*smst((thrDb - L)/12) : -rngDb);
  ) : (
    te = op ? thrDb - hyDb : thrDb;
    b = te - L;
    g = -min(rngDb, (knee ? softk(b, 10) : max(0, b))*(ratV - 1));
  );
  fnc ? g = -rngDb - g;                        // duck = the curve flipped inside the range
  g;
);

// ---- per-channel detector (instance state) ----
function envf(r) instance(env) (
  env = r > env ? r : env*dRel;
  env < 0.0000000001 ? env = 0;
  env;
);
// level (dB) -> smoothed gain (dB): comparator with hysteresis + hold, RC in the dB domain
function gstep(lv) instance(hl, hc, op, g, tg) local(above) (
  above = op ? (lv >= thrDb - hyDb) : (lv >= thrDb);
  above ? ( op = 1; hc = holdS; hl = lv; ) : (
    hc > 0 ? hc -= 1 : ( op = 0; hl = lv; );
  );
  tg = tgain(hl, op);
  tg > g ? g += (tg - g)*(fnc ? cRel : cAtk) : g += (tg - g)*(fnc ? cAtk : cRel);
  g;
);

// ---- memory ----
DLN = 4096;                                    // lookahead delay (10 ms at 192 kHz = 1920)
bufA = alloc(DLN); bufB = alloc(DLN);
cH = alloc(5); cL = alloc(5); cP = alloc(5);
sH0 = alloc(4); sH1 = alloc(4); sL0 = alloc(4); sL1 = alloc(4); sP0 = alloc(4); sP1 = alloc(4);
mq = alloc(3*1024);                            // MIDI event queue (offset, channel, +1 / -1)
HN = 512; hb = alloc(HN*5);                    // level history: in, out, gain, open, key
memset(bufA, 0, DLN); memset(bufB, 0, DLN); memset(hb, 0, HN*5);
k = 0; loop(HN, hb[k*5] = -90; hb[k*5 + 1] = -90; hb[k*5 + 4] = -90; k += 1; );
dw = 0; hpos = 0; hcnt = 0; hInP = 0; hOutP = 0; hG = 0; hOp = 0; hKey = -160;
hstep = max(1, floor(srate*3.4/HN));
dRel = exp(-1/(0.015*srate));
nmA = 0; nmB = 0;
mIL = mIR = mOL = mOR = 0; mDec = exp(-1/(0.25*srate));
detA.g = 0; detB.g = 0; detA.op = 0; detB.op = 0;
lastF = -1;

// ---- presets ----
function pdyn(m, f, kn, th, rg, ra, at, ho, re, hy, la) (
  slider2 = m; slider3 = f; slider4 = kn; slider5 = th; slider6 = rg; slider7 = ra;
  slider8 = at; slider9 = ho; slider10 = re; slider11 = hy; slider12 = la;
);
function pkey(src, mi, st, lk, hp, lp, ff, fg) (
  slider13 = src; slider14 = mi; slider15 = st; slider16 = lk;
  slider17 = hp; slider18 = lp; slider19 = ff; slider20 = fg;
);
function apply_preset(n) (
  pdyn(0, 0, 0, -40, 60, 2, 0.5, 50, 150, 4, 0);
  pkey(0, 0, 0, 100, 20, 20000, 1000, 0);
  slider21 = 0; slider22 = 100; slider23 = 0;
  n == 1  ? ( pdyn(0, 0, 0, -30, 60, 2, 0.1, 30, 90, 6, 2);       pkey(0, 0, 0, 100, 30, 400, 80, 6); ) :
  n == 2  ? ( pdyn(0, 0, 0, -28, 40, 2, 0.05, 40, 120, 6, 1.5);   pkey(0, 0, 0, 100, 150, 8000, 2000, 6); ) :
  n == 3  ? ( pdyn(0, 0, 1, -36, 30, 2, 1, 120, 400, 8, 2);       pkey(0, 0, 0, 100, 60, 3000, 120, 4); ) :
  n == 4  ? ( pdyn(0, 0, 0, -34, 24, 2, 0.05, 15, 60, 5, 1);      pkey(0, 0, 0, 100, 4000, 20000, 8000, 3); ) :
  n == 5  ? ( pdyn(1, 0, 1, -45, 12, 2, 2, 80, 250, 3, 0);        pkey(0, 0, 0, 100, 100, 20000, 3000, 0); ) :
  n == 6  ? ( pdyn(0, 0, 1, -55, 40, 2, 1, 60, 300, 8, 0);        pkey(0, 0, 0, 100, 80, 6000, 1000, 0); ) :
  n == 7  ? ( pdyn(1, 0, 0, -50, 30, 3, 3, 50, 200, 4, 0);        pkey(0, 0, 0, 100, 20, 20000, 1000, 0); ) :
  n == 8  ? ( pdyn(1, 0, 1, -40, 15, 1.5, 5, 20, 300, 2, 0);      pkey(0, 0, 0, 100, 20, 20000, 1000, 0); ) :
  n == 9  ? ( pdyn(1, 0, 1, -32, 18, 2.5, 2, 60, 350, 4, 0);      pkey(0, 0, 0, 100, 60, 20000, 1000, 0); ) :
  n == 10 ? ( pdyn(1, 0, 1, -48, 20, 2, 2, 100, 300, 4, 0);       pkey(0, 0, 0, 100, 120, 8000, 2500, 4); ) :
  n == 11 ? ( pdyn(0, 1, 1, -30, 9, 2, 5, 40, 250, 4, 0);         pkey(1, 0, 0, 100, 20, 200, 80, 0); ) :
  n == 12 ? ( pdyn(1, 1, 1, -40, 12, 4, 20, 200, 800, 3, 0);      pkey(1, 0, 0, 100, 150, 6000, 1500, 0); ) :
  n == 13 ? ( pdyn(0, 0, 0, -24, 80, 2, 0.05, 250, 40, 10, 0);    pkey(0, 0, 0, 100, 20, 20000, 1000, 0); ) :
  n == 14 ? ( pdyn(0, 0, 0, 0, 80, 2, 0.2, 0, 20, 0, 0);          pkey(0, 1, 0, 100, 20, 20000, 1000, 0); ) :
  n == 15 ? ( pdyn(0, 0, 0, -32, 50, 2, 0.01, 50, 100, 6, 5);     pkey(0, 0, 0, 100, 40, 20000, 1000, 0); );
);

// GUI state
drag_id = -1; pcap = 0; lastS = 0; k_rst = -1; lcd_t = 0;
gfx_ext_retina = 1;

q_init == 0 ? (
  lastPreset = slider1;
  ui_sz = 2;                                   // open with large text
  q_init = 1;
);

@serialize
file_var(0, ui_sz);
file_var(0, lastPreset);

@slider
slider1 != lastPreset ? ( apply_preset(slider1); lastPreset = slider1; );

@block
// ---- parameters ----
mdl = slider2 > 0.5; fnc = slider3 > 0.5; knee = slider4 > 0.5;
thrDb = slider5; rngDb = slider6; ratV = max(1, slider7);
hyDb = slider11;
cAtk = cms(slider8*0.001/3);                   // ~95% in the attack time
cRel = cms(slider10*0.001/3);
holdS = floor(slider9*0.001*srate);
la = min(DLN - 2, floor(slider12*0.001*srate + 0.5));
pdc_delay = la; pdc_bot_ch = 0; pdc_top_ch = 2;
ext = slider13 > 0.5; midiOn = slider14 > 0.5;
smode = floor(slider15 + 0.5); lnk = slider16/100;
listen = slider21 > 0.5;
mix = slider22/100; outG = db2g(slider23);

// key filters (rebuilt only when changed)
fsum = slider17 + slider18*3 + slider19*7 + slider20*11;
fsum != lastF ? (
  lastF = fsum;
  hpOn = slider17 > 20.5;  hpOn ? cHP(cH, slider17, 0.7071);
  lpOn = slider18 < 19999; lpOn ? cLP(cL, slider18, 0.7071);
  pkOn = abs(slider20) > 0.05; pkOn ? cPK(cP, slider19, slider20, 1.4);
);

// ---- MIDI: queue note on/off for sample-accurate triggering, pass everything through ----
qn = 0;
while (midirecv(mofs, m1, m2, m3)) (
  midisend(mofs, m1, m2, m3);
  mst = m1 & 0xF0; mch = m1 & 0x0F;
  (midiOn && mch <= 2 && (mst == 0x90 || mst == 0x80) && qn < 1024) ? (
    mq[qn*3] = mofs; mq[qn*3 + 1] = mch; mq[qn*3 + 2] = (mst == 0x90 && m3 > 0) ? 1 : -1;
    qn += 1;
  );
  (mst == 0xB0 && (m2 == 123 || m2 == 120)) ? ( nmA = 0; nmB = 0; );
);
!midiOn ? ( nmA = 0; nmB = 0; );
qi = 0; si = 0;

@sample
// ---- MIDI events due at this sample ----
while (qi < qn && mq[qi*3] <= si) (
  mch = mq[qi*3 + 1]; md = mq[qi*3 + 2];
  mch == 0 ? ( nmA = max(0, nmA + md); nmB = max(0, nmB + md); ) :
  mch == 1 ? nmA = max(0, nmA + md) : nmB = max(0, nmB + md);
  qi += 1;
);
si += 1;

x0 = spl0; x1 = spl1;
ext ? ( k0 = spl2; k1 = spl3; ) : ( k0 = x0; k1 = x1; );
smode == 2 ? (
  a0 = (x0 + x1)*0.5; a1 = (x0 - x1)*0.5;
  kt = (k0 + k1)*0.5; k1 = (k0 - k1)*0.5; k0 = kt;
) : ( a0 = x0; a1 = x1; );

// ---- key filters ----
hpOn ? ( k0 = bqf(k0, cH, sH0); k1 = bqf(k1, cH, sH1); );
lpOn ? ( k0 = bqf(k0, cL, sL0); k1 = bqf(k1, cL, sL1); );
pkOn ? ( k0 = bqf(k0, cP, sP0); k1 = bqf(k1, cP, sP1); );

// ---- detectors ----
lvA = g2db(detA.envf(abs(k0)));
lvB = g2db(detB.envf(abs(k1)));
smode == 0 ? (
  lv = max(lvA, lvB);
  (nmA + nmB) > 0 ? lv = 40;
  gA = detA.gstep(lv); gB = gA;
  detB.op = detA.op; lvA = lvB = lv;
) : (
  mxl = max(lvA, lvB);
  lvA += lnk*(mxl - lvA); lvB += lnk*(mxl - lvB);
  nmA > 0 ? lvA = 40;
  nmB > 0 ? lvB = 40;
  gA = detA.gstep(lvA); gB = detB.gstep(lvB);
);

// ---- lookahead delay on the audio path ----
bufA[dw] = a0; bufB[dw] = a1;
rp = dw - la; rp < 0 ? rp += DLN;
d0 = bufA[rp]; d1 = bufB[rp];
dw += 1; dw >= DLN ? dw = 0;

// ---- VCA + mix ----
o0 = d0*(1 - mix + mix*db2g(gA));
o1 = d1*(1 - mix + mix*db2g(gB));
listen ? ( o0 = k0; o1 = k1; );
smode == 2 ? ( y0 = o0 + o1; y1 = o0 - o1; ) : ( y0 = o0; y1 = o1; );
spl0 = y0*outG; spl1 = y1*outG;

// ---- meters ----
mIL = max(abs(x0), mIL*mDec); mIR = max(abs(x1), mIR*mDec);
mOL = max(abs(spl0), mOL*mDec); mOR = max(abs(spl1), mOR*mDec);
mGA = gA; mGB = gB; mLv = max(lvA, lvB);
hInP = max(hInP, max(abs(x0), abs(x1)));
hOutP = max(hOutP, max(abs(spl0), abs(spl1)));
hG = min(hG, min(gA, gB));
hOp = hOp || detA.op || detB.op;
hKey = max(hKey, min(0, mLv));
hcnt += 1;
hcnt >= hstep ? (
  hp_ = hb + hpos*5;
  hp_[0] = g2db(hInP); hp_[1] = g2db(hOutP); hp_[2] = hG; hp_[3] = hOp; hp_[4] = hKey;
  hpos += 1; hpos >= HN ? hpos = 0;
  hcnt = 0; hInP = 0; hOutP = 0; hG = 0; hOp = 0; hKey = -160;
);

@gfx 1500 520

// =====================================================================
// GUI - vintage rack: slate blue-grey faceplate, cream silk-screen, black/aluminium knobs,
// lamp push-buttons, phosphor display. 1500 x 520 design space scaled to fill the window
// (proportions kept). SIZE S / M / L sets the panel size.
// =====================================================================

szf = ui_sz == 1 ? 0.6 : ui_sz == 2 ? 0.9 : 0.75;          // S / M / L: panel size
S  = min(szf, min(gfx_w/1500, gfx_h/520));
tf = 1;
ox = floor((gfx_w - 1500*S)*0.5);
oy = floor((gfx_h - 520*S)*0.5);
mx = (mouse_x - ox)/S;
my = (mouse_y - oy)/S;

// the ? pop-up is modal: while it is open the panel underneath takes no clicks
hlp ? ( (mouse_cap & 1) && !(pcap & 1) && !hlp_new ? hlp = 0; pcap = mouse_cap; );
hlp_new = 0;

(S != lastS || tf != lastTf) ? (
  gfx_setfont(1, "Arial Black", max(12, 36*S));             // brand
  gfx_setfont(2, "Arial Bold", max(10, 13*S*tf));            // frame tabs
  gfx_setfont(3, "Arial Bold", max(10, 15*S*tf));            // knob labels
  gfx_setfont(4, "Arial Bold", max(10, 14*S*tf));            // values
  gfx_setfont(5, "Arial Bold", max(9, 12*S*tf));             // small print
  gfx_setfont(6, "Arial Bold", max(10, 14*S*tf));            // buttons
  gfx_setfont(7, "Courier New", max(11, 22*S), 'b');         // LCD line 2
  gfx_setfont(8, "Courier New", max(10, 14*S*tf), 'b');      // LCD line 1
  gfx_setfont(9, "Arial", max(9, 11*S*tf));                  // display scale
  lastS = S; lastTf = tf;
);

// ---- palette ----
function col(r, g, b) ( gfx_r = r; gfx_g = g; gfx_b = b; gfx_a = 1; );
function cface() ( col(0.40, 0.45, 0.52); );
function cink() ( col(0.94, 0.93, 0.87); );                    // cream silk-screen
function cdim() ( col(0.70, 0.73, 0.76); );
function cdark() ( col(0.09, 0.10, 0.11); );
function ctab() ( col(0.18, 0.33, 0.53); );

// ---- drawing helpers (design space) ----
function R(x, y, w, h) ( gfx_rect(ox + x*S, oy + y*S, max(1, w*S), max(1, h*S)); );
function RO(x, y, w, h) ( gfx_rect(ox + x*S, oy + y*S, max(1, w*S), max(1, h*S), 0); );
function LN(x1, y1, x2, y2) ( gfx_line(ox + x1*S, oy + y1*S, ox + x2*S, oy + y2*S, 1); );
function TX(x, y, txt) ( gfx_x = ox + x*S; gfx_y = oy + y*S; gfx_drawstr(txt); );
function TC(cx, y, txt) local(w, h) ( gfx_measurestr(txt, w, h); gfx_x = ox + cx*S - w*0.5; gfx_y = oy + y*S; gfx_drawstr(txt); );
function TR(rx, y, txt) local(w, h) ( gfx_measurestr(txt, w, h); gfx_x = ox + rx*S - w; gfx_y = oy + y*S; gfx_drawstr(txt); );
function CIRC(x, y, rr, fill) ( gfx_circle(ox + x*S, oy + y*S, rr*S, fill, 1); );
function clicked(x, y, w, h) ( (mouse_cap & 1) && !(pcap & 1) && mx >= x && mx <= x+w && my >= y && my <= y+h; );
// write a slider and tell REAPER (so GUI moves record as automation)
function setk(idx, v) ( slider(idx) != v ? ( slider(idx) = v; slider_automate(2^(idx - 1)); ); );

function screw(x, y) (
  col(0.62, 0.63, 0.65); CIRC(x, y, 7, 1);
  col(0.30, 0.31, 0.33); CIRC(x, y, 7, 0);
  LN(x - 4, y - 4, x + 4, y + 4);
);

// Frame: cream outline with a blue title tab
function frame(x, y, w, h, title) local(tw, th) (
  col(0.33, 0.37, 0.43); R(x, y, w, h);
  col(0.60, 0.64, 0.69); RO(x, y, w, h);
  gfx_setfont(2); gfx_measurestr(title, tw, th);
  ctab(); R(x + 12, y - 9, tw/S + 16, 18);
  cink(); TX(x + 20, y - 8, title);
);

// Lamp push-button. lamp: 0 amber, 1 green, 2 red
function btn(x, y, w, h, lbl, on, lamp) local(sw, sh) (
  cdark(); R(x - 2, y - 2, w + 4, h + 4);
  on ? (
    lamp == 0 ? col(1.00, 0.72, 0.22) : lamp == 1 ? col(0.42, 0.95, 0.48) : col(1.00, 0.30, 0.22);
    R(x, y, w, h);
    lamp == 0 ? col(1.00, 0.86, 0.55) : lamp == 1 ? col(0.70, 1.00, 0.72) : col(1.00, 0.60, 0.52);
    R(x + 3, y + 2, w - 6, 3);
    col(0.12, 0.08, 0.04);
  ) : (
    col(0.24, 0.25, 0.27); R(x, y, w, h);
    col(0.32, 0.33, 0.35); R(x + 3, y + 2, w - 6, 3);
    col(0.72, 0.73, 0.74);
  );
  gfx_setfont(6); gfx_measurestr(lbl, sw, sh);
  gfx_x = ox + (x + w*0.5)*S - sw*0.5; gfx_y = oy + (y + h*0.5)*S - sh*0.5 + 1;
  gfx_drawstr(lbl);
  clicked(x, y, w, h);
);

// value <-> knob travel. m: 0 linear, 1 log, 2 squared
function k2v(fr, a, b, m) ( m == 1 ? a*(b/a)^fr : m == 2 ? a + (b - a)*fr*fr : a + (b - a)*fr; );
function v2k(v, a, b, m) ( max(0, min(1, m == 1 ? log(v/a)/log(b/a) : m == 2 ? sqrt(max(0, (v - a)/(b - a))) : (v - a)/(b - a))); );

// Vintage knob: black skirt with white index, aluminium cap. dim = greyed (inactive)
function knob(id, cx, cy, rad, v, a, b, m, def, dim) local(dx, dy, fr, nf, ang, sx, sy, sr, k, t, ca, sa, ta) (
  fr = v2k(v, a, b, m);
  dx = mx - cx; dy = my - cy;
  kn_hot = drag_id == id || (dx*dx + dy*dy) < (rad*rad*1.6);   // house style: values show on hover / drag only
  (mouse_cap & 1) && !(pcap & 1) && drag_id == -1 && (dx*dx + dy*dy) < (rad*rad*1.6) ? (
    ((mouse_cap & 4) || (kc_id == id && time_precise() - kc_t < 0.35)) ? (
      v = def; kc_t = 0; k_rst = id;
    ) : (
      drag_id = id; drag_sy = my; drag_sf = fr; kc_id = id; kc_t = time_precise();
    );
  );
  drag_id == id ? (
    (mouse_cap & 1) ? (
      nf = max(0, min(1, drag_sf + (drag_sy - my)/((mouse_cap & 8) ? 800 : 200)));
      v = k2v(nf, a, b, m);
    ) : drag_id = -1;
  );
  fr = v2k(v, a, b, m);
  ang = (-0.75 + 1.5*fr)*$pi;
  sx = ox + cx*S; sy = oy + cy*S; sr = rad*S;

  // silk-screen scale
  dim ? col(0.55, 0.59, 0.64) : cink();
  k = 0;
  loop(11,
    ta = (-0.75 + 1.5*k/10)*$pi;
    t = (k == 0 || k == 10 || k == 5) ? 9 : 5;
    gfx_line(sx + sin(ta)*(sr + 4*S), sy - cos(ta)*(sr + 4*S), sx + sin(ta)*(sr + (4 + t)*S), sy - cos(ta)*(sr + (4 + t)*S), 1);
    k += 1;
  );
  // shadow, skirt, ribs
  col(0.22, 0.25, 0.29); gfx_circle(sx + 2*S, sy + 3*S, sr, 1, 1);
  col(0.05, 0.05, 0.06); gfx_circle(sx, sy, sr, 1, 1);
  col(0.15, 0.15, 0.17); k = 0;
  loop(24,
    ta = k*2*$pi/24;
    gfx_line(sx + sin(ta)*sr*0.80, sy - cos(ta)*sr*0.80, sx + sin(ta)*(sr - 1), sy - cos(ta)*(sr - 1), 1);
    k += 1;
  );
  // white index on the skirt
  sa = sin(ang); ca = cos(ang);
  dim ? col(0.55, 0.55, 0.55) : col(0.97, 0.97, 0.94);
  t = max(2, floor(3*S + 0.5)); k = 0;
  loop(t,
    gfx_line(sx + sa*sr*0.62 + ca*(k - t*0.5), sy - ca*sr*0.62 + sa*(k - t*0.5),
             sx + sa*sr*0.97 + ca*(k - t*0.5), sy - ca*sr*0.97 + sa*(k - t*0.5), 1);
    k += 1;
  );
  // aluminium cap with a dark index
  id == 11 ? (                                   // KEY HPF: house-style yellow cap
    col(0.62, 0.50, 0.08); gfx_circle(sx, sy, sr*0.58, 1, 1);
    col(0.95, 0.76, 0.11); gfx_circle(sx, sy, sr*0.53, 1, 1);
    col(1.00, 0.88, 0.45); gfx_circle(sx - sr*0.16, sy - sr*0.18, sr*0.16, 1, 1);
  ) : (
  col(0.46, 0.47, 0.49); gfx_circle(sx, sy, sr*0.58, 1, 1);
  dim ? col(0.52, 0.53, 0.55) : col(0.74, 0.75, 0.77); gfx_circle(sx, sy, sr*0.53, 1, 1);
  col(0.86, 0.87, 0.89); gfx_circle(sx - sr*0.16, sy - sr*0.18, sr*0.16, 1, 1);
  );
  col(0.15, 0.15, 0.16);
  gfx_line(sx + sa*sr*0.12, sy - ca*sr*0.12, sx + sa*sr*0.50, sy - ca*sr*0.50, 1);
  gfx_line(sx + sa*sr*0.12 + ca, sy - ca*sr*0.12 + sa, sx + sa*sr*0.50 + ca, sy - ca*sr*0.50 + sa, 1);
  v;
);

function touch(id, name, val) (
  (drag_id == id || k_rst == id) ? (
    strcpy(#lcdn, name); strcpy(#lcdv, val); lcd_t = time_precise();
    k_rst == id ? k_rst = -1;
  );
);

// ---- value formatting ----
function fdb(v) local(q) (
  q = floor(v*10 + 0.5)/10;
  q > 0 ? sprintf(#vt, "+%.1f dB", q) : q < 0 ? sprintf(#vt, "%.1f dB", q) : strcpy(#vt, "0.0 dB");
  #vt;
);
function fms(v) (
  v >= 1000 ? sprintf(#vt, "%.2f s", v/1000) : v >= 100 ? sprintf(#vt, "%d ms", floor(v + 0.5)) :
  v >= 10 ? sprintf(#vt, "%.1f ms", v) : sprintf(#vt, "%.2f ms", v);
  #vt;
);
function fhz(v) ( v >= 1000 ? sprintf(#vt, "%.2g kHz", v/1000) : sprintf(#vt, "%d Hz", floor(v + 0.5)); #vt; );
function fpct(v) ( sprintf(#vt, "%d%%", floor(v + 0.5)); #vt; );

function pname(n) (
  n == 0 ? "INIT" : n == 1 ? "KICK TIGHT" : n == 2 ? "SNARE CRACK" : n == 3 ? "TOM CLEANUP" :
  n == 4 ? "HI-HAT CLEAN" : n == 5 ? "VOCAL BREATH" : n == 6 ? "GUITAR NOISE" : n == 7 ? "BASS DI" :
  n == 8 ? "GENTLE EXPAND" : n == 9 ? "ROOM MIC TAME" : n == 10 ? "DIALOGUE CLEAN" : n == 11 ? "KICK DUCK EXT" :
  n == 12 ? "VO DUCK EXT" : n == 13 ? "GATED VERB 80S" : n == 14 ? "MIDI CHOP" : "LOOKAHEAD DRUM";
);
function step_preset(dir) (
  slider1 = (slider1 + dir + 16) % 16;
  apply_preset(slider1); lastPreset = slider1; lcd_t = 0;
  slider_automate(8388607);                    // sliders 1-23
);
function setmsg(n, v) ( strcpy(#lcdn, n); strcpy(#lcdv, v); lcd_t = time_precise(); );

// LED ladder. m 0 = level (dBFS, -60..0 upward), 1 = gain reduction (0..-60 downward)
function ladder(x, y, h, val, m) local(k, n, sh, lit, sy) (
  n = 24; sh = h/n;
  cdark(); R(x - 3, y - 3, 22, h + 6);
  k = 0;
  loop(n,
    m == 0 ? (
      lit = val >= -60 + (k + 1)*2.5;
      sy = y + h - (k + 1)*sh;
      k >= 22 ? (lit ? col(1.0, 0.25, 0.18) : col(0.30, 0.08, 0.06)) :
      k >= 18 ? (lit ? col(1.0, 0.75, 0.20) : col(0.30, 0.22, 0.06)) :
                (lit ? col(0.40, 0.95, 0.45) : col(0.08, 0.24, 0.10));
    ) : (
      lit = -val >= (k + 0.5)*2.5;
      sy = y + k*sh;
      lit ? col(1.0, 0.68, 0.18) : col(0.30, 0.20, 0.06);
    );
    R(x, sy + 1, 16, sh - 2);
    k += 1;
  );
);

function led(x, y, on, c) (
  cdark(); CIRC(x, y, 8, 1);
  on ? (
    c == 1 ? col(0.40, 1.0, 0.45) : c == 2 ? col(1.0, 0.30, 0.20) : col(1.0, 0.72, 0.20);
  ) : (
    c == 1 ? col(0.08, 0.25, 0.10) : c == 2 ? col(0.28, 0.07, 0.05) : col(0.28, 0.20, 0.05);
  );
  CIRC(x, y, 6, 1);
  on ? ( col(1, 1, 1); CIRC(x - 2, y - 2, 1.6, 1); );
);

// =====================================================================
// Draw
// =====================================================================
col(0.13, 0.14, 0.16); gfx_rect(0, 0, gfx_w, gfx_h);
cface(); R(0, 0, 1500, 520);
// rack ears
e = 0;
loop(2,
  ex = e == 0 ? 0 : 1464;
  col(0.35, 0.39, 0.45); R(ex, 0, 36, 520);
  col(0.28, 0.31, 0.36); R(e == 0 ? 35 : 1464, 0, 1, 520);
  cdark(); R(ex + 10, 52, 16, 26); R(ex + 10, 442, 16, 26);
  col(0.20, 0.22, 0.25); R(ex + 12, 54, 12, 22); R(ex + 12, 444, 12, 22);
  e += 1;
);
col(0.52, 0.57, 0.63); R(36, 0, 1428, 2);
col(0.27, 0.30, 0.35); R(36, 518, 1428, 2);

// ---- brand, LCD, presets, text size ----
cink(); gfx_setfont(1); TX(52, 14, "GFX GATE");
gfx_setfont(5); cdim(); TX(54, 58, "GATE · EXPANDER · DUCKER");

cdark(); R(52, 82, 270, 84);
col(0.06, 0.04, 0.02); R(56, 86, 262, 76);
col(1.0, 0.68, 0.15);
time_precise() - lcd_t < 1.5 ? (
  gfx_setfont(8); TX(68, 96, #lcdn);
  gfx_setfont(7); TX(68, 122, #lcdv);
) : (
  gfx_setfont(8); sprintf(#lcd1, "PRESET %02d/16", slider1 + 1); TX(68, 96, #lcd1);
  gfx_setfont(7); TX(68, 122, pname(slider1));
);
// PRESETS key or a click on the LCD: every preset in a drop-down
pm_ = btn(52, 180, 136, 32, "PRESETS", 0, 0);
clicked(52, 82, 270, 84) || pm_ ? (
  strcpy(#pmenu, ""); k = 0;
  loop(16,
    k == slider1 ? strcat(#pmenu, "!");
    strcat(#pmenu, pname(k));
    k < 15 ? strcat(#pmenu, "|");
    k += 1;
  );
  gfx_x = mouse_x; gfx_y = mouse_y;
  psel = gfx_showmenu(#pmenu);
  psel > 0 ? ( slider1 = psel - 1; apply_preset(slider1); lastPreset = slider1; lcd_t = 0; slider_automate(8388607); );
);

btn(198, 180, 58, 32, "◄", 0, 0) ? step_preset(-1);
btn(264, 180, 58, 32, "►", 0, 0) ? step_preset(1);

cink(); gfx_setfont(5); TX(52, 238, "SIZE");
btn(110, 230, 46, 30, "S", ui_sz == 1, 0) ? ui_sz = 1;
btn(164, 230, 46, 30, "M", ui_sz == 0, 0) ? ui_sz = 0;
btn(218, 230, 46, 30, "L", ui_sz == 2, 0) ? ui_sz = 2;
btn(272, 230, 46, 30, "?", hlp, 0) ? ( hlp = 1; hlp_new = 1; );

// ---- level history display ----
cdark(); R(336, 16, 584, 232);
col(0.02, 0.06, 0.04); R(342, 22, 572, 220);
pX = 342; pW = 572; pY = 32; pH = 186;                  // 0 dB at pY, -80 dB at pY + pH
function yy(d) ( pY + (-max(-80, min(0, d)))/80*pH; );
gfx_setfont(9);
k = 0;
loop(5,
  col(0.07, 0.20, 0.11); LN(pX, yy(-k*20), pX + pW, yy(-k*20));
  k += 1;
);
// key level (only meaningful when the key differs from the input)
keyShow = ext || hpOn || lpOn || pkOn || smode != 0;
// input fill, output trace, gain trace, key trace
k = 0; px_ = 0;
loop(HN,
  hq_ = hb + ((hpos + k) % HN)*5;
  xk = pX + k*pW/HN;
  col(0.07, 0.26, 0.14); LN(xk, yy(hq_[0]), xk, pY + pH);
  hq_[3] > 0.5 ? ( col(0.25, 0.80, 0.40); LN(xk, pY + pH + 6, xk + 1, pY + pH + 6); LN(xk, pY + pH + 7, xk + 1, pY + pH + 7); );
  k > 0 ? (
    keyShow ? ( col(0.25, 0.65, 0.85); LN(xk - pW/HN, yy(pk_), xk, yy(hq_[4])); );
    col(0.45, 1.0, 0.60); LN(xk - pW/HN, yy(po_), xk, yy(hq_[1]));
    col(1.0, 0.70, 0.22); LN(xk - pW/HN, yy(pg_), xk, yy(hq_[2]));
  );
  po_ = hq_[1]; pg_ = hq_[2]; pk_ = hq_[4];
  k += 1;
);
// dB scale on a dark tab so the traces never hide it
k = 0;
loop(5,
  col(0.02, 0.06, 0.04); R(pX + 1, yy(-k*20) - (k == 4 ? 14 : k == 0 ? 0 : 7), 28, 14);
  col(0.30, 0.65, 0.40); sprintf(#vt, "%d", -k*20); TX(pX + 4, yy(-k*20) - (k == 4 ? 14 : k == 0 ? 0 : 7), #vt);
  k += 1;
);
// thresholds: open (solid) and close (thin)
col(1.0, 0.32, 0.24); LN(pX, yy(thrDb), pX + pW, yy(thrDb)); LN(pX, yy(thrDb) + 1, pX + pW, yy(thrDb) + 1);
hyDb > 0.05 ? ( col(0.65, 0.20, 0.16); k = 0; loop(57, LN(pX + k*10, yy(thrDb - hyDb), pX + k*10 + 5, yy(thrDb - hyDb)); k += 1; ); );
gfx_setfont(9);
col(0.45, 1.0, 0.60); TR(pX + pW - 150, pY - 8, "OUT");
col(1.0, 0.70, 0.22); TR(pX + pW - 100, pY - 8, "GAIN");
col(1.0, 0.32, 0.24); TR(pX + pW - 48, pY - 8, "THRESH");
keyShow ? ( col(0.25, 0.65, 0.85); TR(pX + pW - 196, pY - 8, "KEY"); );
col(0.25, 0.80, 0.40); TX(pX + pW - 54, pY + pH + 10, fnc ? "DUCKED" : "OPEN");

// ---- transfer curve ----
cdark(); R(932, 16, 232, 232);
col(0.02, 0.06, 0.04); R(938, 22, 220, 220);
tX = 962; tY = 34; tS = 186;
function tx_(d) ( tX + (max(-80, min(0, d)) + 80)/80*tS; );
function ty_(d) ( tY + (-max(-80, min(0, d)))/80*tS; );
k = 1;
loop(3,
  col(0.07, 0.20, 0.11); LN(tx_(-k*20), tY, tx_(-k*20), tY + tS); LN(tX, ty_(-k*20), tX + tS, ty_(-k*20));
  k += 1;
);
col(0.09, 0.26, 0.15); RO(tX, tY, tS, tS);
!ext ? ( col(0.12, 0.35, 0.20); LN(tX, tY + tS, tX + tS, tY); );     // unity
col(0.65, 0.20, 0.16); LN(tx_(thrDb), tY, tx_(thrDb), tY + tS);
// closing branch (dim) then opening branch (bright)
pass = 0;
loop(2,
  k = 0;
  loop(121,
    Lc = -80 + k*80/120;
    oc = (ext ? 0 : Lc) + tgain(Lc, pass == 0 ? (Lc >= thrDb - hyDb) : (Lc >= thrDb));   // ext key: plot gain vs key
    pass == 0 ? col(0.18, 0.50, 0.30) : col(0.45, 1.0, 0.60);
    k > 0 ? ( LN(tx_(pL), ty_(pO), tx_(Lc), ty_(oc)); LN(tx_(pL), ty_(pO) + 1, tx_(Lc), ty_(oc) + 1); );
    pL = Lc; pO = oc;
    k += 1;
  );
  pass += 1;
);
// live operating point
gfx_mcl = max(-80, min(0, mLv));
col(1.0, 0.70, 0.22); CIRC(tx_(gfx_mcl), ty_((ext ? 0 : gfx_mcl) + min(mGA, mGB)), 4, 1);
gfx_setfont(9); col(0.20, 0.50, 0.30);
TC(tX + tS*0.5, tY + tS + 4, ext ? "KEY dB" : "IN dB");
TX(tX + 4, tY + 2, ext ? "GAIN" : "OUT");

// ---- meters ----
frame(1176, 18, 276, 230, "METERS");
gfx_setfont(5); cink();
TC(1206, 30, "IN"); TC(1286, 30, "GR"); TC(1366, 30, "OUT");
ladder(1188, 48, 176, g2db(mIL), 0); ladder(1214, 48, 176, g2db(mIR), 0);
ladder(1268, 48, 176, mGA, 1);       ladder(1294, 48, 176, mGB, 1);
ladder(1348, 48, 176, g2db(mOL), 0); ladder(1374, 48, 176, g2db(mOR), 0);
cdim(); gfx_setfont(9);
TC(1196, 230, smode == 2 ? "L" : "L"); TC(1222, 230, "R");
TC(1276, 230, smode == 2 ? "M" : "L"); TC(1302, 230, smode == 2 ? "S" : "R");
TC(1356, 230, "L"); TC(1382, 230, "R");
gfx_setfont(5); cink(); TC(1424, 30, "GATE");
led(1424, 60, detA.op, 1);  cdim(); gfx_setfont(9); TC(1424, 72, smode == 2 ? "M" : smode == 1 ? "L" : "L+R");
led(1424, 108, detB.op, 1); cdim(); TC(1424, 120, smode == 2 ? "S" : smode == 1 ? "R" : "L+R");
led(1424, 156, (nmA + nmB) > 0, 0); cdim(); TC(1424, 168, "MIDI");
led(1424, 204, listen, 2); cdim(); TC(1424, 216, "LSTN");

// ---- mode buttons ----
gfx_setfont(5); cink();
TX(336, 268, "MODEL");
btn(398, 260, 70, 32, "GATE", !mdl, 0) ? ( setk(2, 0); setmsg("MODEL", "GATE"); );
btn(474, 260, 70, 32, "EXP", mdl, 0) ? ( setk(2, 1); setmsg("MODEL", "EXPANDER"); );
cink(); gfx_setfont(5); TX(568, 268, "FUNCTION");
btn(646, 260, 70, 32, "NORM", !fnc, 0) ? ( setk(3, 0); setmsg("FUNCTION", "NORMAL"); );
btn(722, 260, 70, 32, "DUCK", fnc, 2) ? ( setk(3, 1); setmsg("FUNCTION", "DUCK"); );
cink(); gfx_setfont(5); TX(816, 268, "KNEE");
btn(866, 260, 70, 32, "HARD", !knee, 0) ? ( setk(4, 0); setmsg("KNEE", "HARD"); );
btn(942, 260, 70, 32, "SOFT", knee, 0) ? ( setk(4, 1); setmsg("KNEE", "SOFT"); );
cink(); gfx_setfont(5); TX(1036, 268, "STEREO");
btn(1100, 260, 70, 32, "LINK", smode == 0, 1) ? ( setk(15, 0); setmsg("STEREO", "LINKED"); );
btn(1176, 260, 70, 32, "DUAL", smode == 1, 1) ? ( setk(15, 1); setmsg("STEREO", "DUAL MONO"); );
btn(1252, 260, 70, 32, "M/S", smode == 2, 1) ? ( setk(15, 2); setmsg("STEREO", "MID / SIDE"); );
// latency readout
cdim(); gfx_setfont(9);
la > 0 ? sprintf(#lat, "LATENCY %.1f ms", la*1000/srate) : strcpy(#lat, "ZERO LATENCY");
TR(1452, 270, #lat);

// ---- dynamics knobs ----
frame(52, 318, 790, 188, "DYNAMICS");
kx = 102;
setk(5, knob(1, kx, 400, 30, slider5, -80, 0, 0, -40, 0));
cink(); gfx_setfont(3); TC(kx, 446, "THRESHOLD"); gfx_setfont(4); kn_hot ? TC(kx, 468, fdb(slider5)); touch(1, "THRESHOLD", fdb(slider5));
kx += 98;
setk(6, knob(2, kx, 400, 30, slider6, 0, 80, 0, 60, 0));
cink(); gfx_setfont(3); TC(kx, 446, "RANGE"); gfx_setfont(4); kn_hot ? TC(kx, 468, fdb(-slider6)); touch(2, fnc ? "DUCK RANGE" : "RANGE", fdb(-slider6));
kx += 98;
setk(7, knob(3, kx, 400, 30, slider7, 1, 10, 1, 2, !mdl));
!mdl ? col(0.62, 0.66, 0.71) : cink(); gfx_setfont(3); TC(kx, 446, "RATIO");
sprintf(#rt, "1:%.1f", slider7); gfx_setfont(4); TC(kx, 468, mdl ? (kn_hot ? #rt : "") : "GATE");
touch(3, "RATIO (EXP)", #rt);
kx += 98;
setk(8, knob(4, kx, 400, 30, slider8, 0.01, 100, 1, 0.5, 0));
cink(); gfx_setfont(3); TC(kx, 446, "ATTACK"); gfx_setfont(4); kn_hot ? TC(kx, 468, fms(slider8)); touch(4, "ATTACK", fms(slider8));
kx += 98;
setk(9, knob(5, kx, 400, 30, slider9, 0, 2000, 2, 50, 0));
cink(); gfx_setfont(3); TC(kx, 446, "HOLD"); gfx_setfont(4); kn_hot ? TC(kx, 468, fms(slider9)); touch(5, "HOLD", fms(slider9));
kx += 98;
setk(10, knob(6, kx, 400, 30, slider10, 5, 4000, 1, 150, 0));
cink(); gfx_setfont(3); TC(kx, 446, "RELEASE"); gfx_setfont(4); kn_hot ? TC(kx, 468, fms(slider10)); touch(6, "RELEASE", fms(slider10));
kx += 98;
setk(11, knob(7, kx, 400, 30, slider11, 0, 20, 0, 4, 0));
cink(); gfx_setfont(3); TC(kx, 446, "HYSTERESIS"); sprintf(#hy, "%.1f dB", slider11); gfx_setfont(4); kn_hot ? TC(kx, 468, #hy); touch(7, "HYSTERESIS", #hy);
kx += 98;
setk(12, knob(8, kx, 400, 30, slider12, 0, 10, 0, 0, 0));
slider12 < 0.05 ? strcpy(#lk, "ZERO") : sprintf(#lk, "%.1f ms", slider12);
cink(); gfx_setfont(3); TC(kx, 446, "LOOKAHEAD"); gfx_setfont(4); kn_hot ? TC(kx, 468, #lk); touch(8, "LOOKAHEAD", #lk);

// ---- key section ----
frame(856, 318, 420, 188, "KEY");
btn(870, 334, 58, 30, "INT", !ext, 1) ? ( setk(13, 0); setmsg("KEY SOURCE", "INTERNAL"); );
btn(934, 334, 58, 30, "EXT", ext, 1) ? ( setk(13, 1); setmsg("KEY SOURCE", "EXT 3/4"); );
btn(1006, 334, 64, 30, "MIDI", midiOn, 0) ? ( setk(14, !midiOn); setmsg("MIDI TRIGGER", !midiOn ? "ON  CH1/2/3" : "OFF"); );
btn(1084, 334, 84, 30, "LISTEN", listen, 2) ? ( setk(21, !listen); setmsg("KEY LISTEN", !listen ? "ON" : "OFF"); );
kx = 904;
setk(17, knob(11, kx, 412, 23, slider17, 20, 5000, 1, 20, 0));
slider17 < 20.5 ? strcpy(#fa, "OFF") : strcpy(#fa, fhz(slider17));
cink(); gfx_setfont(3); TC(kx, 446, "HPF"); gfx_setfont(4); TC(kx, 468, slider17 < 20.5 || kn_hot ? #fa : ""); touch(11, "KEY HPF", #fa);
kx += 81;
setk(18, knob(12, kx, 412, 23, slider18, 100, 20000, 1, 20000, 0));
slider18 > 19999 ? strcpy(#fb, "OFF") : strcpy(#fb, fhz(slider18));
cink(); gfx_setfont(3); TC(kx, 446, "LPF"); gfx_setfont(4); TC(kx, 468, slider18 > 19999 || kn_hot ? #fb : ""); touch(12, "KEY LPF", #fb);
kx += 81;
setk(19, knob(13, kx, 412, 23, slider19, 100, 10000, 1, 1000, abs(slider20) < 0.05));
strcpy(#fc, fhz(slider19));
cink(); gfx_setfont(3); TC(kx, 446, "FOCUS"); gfx_setfont(4); kn_hot ? TC(kx, 468, #fc); touch(13, "KEY FOCUS", #fc);
kx += 81;
setk(20, knob(14, kx, 412, 23, slider20, -12, 12, 0, 0, 0));
cink(); gfx_setfont(3); TC(kx, 446, "F.GAIN"); gfx_setfont(4); kn_hot ? TC(kx, 468, fdb(slider20)); touch(14, "FOCUS GAIN", fdb(slider20));
kx += 81;
setk(16, knob(15, kx, 412, 23, slider16, 0, 100, 0, 100, smode == 0));
smode == 0 ? col(0.62, 0.66, 0.71) : cink(); gfx_setfont(3); TC(kx, 446, "LINK"); gfx_setfont(4); TC(kx, 468, smode == 0 ? "FULL" : kn_hot ? fpct(slider16) : "");
touch(15, "STEREO LINK", fpct(slider16));

// ---- master ----
frame(1290, 318, 162, 188, "MASTER");
setk(22, knob(21, 1331, 400, 25, slider22, 0, 100, 0, 100, 0));
cink(); gfx_setfont(3); TC(1331, 446, "MIX"); gfx_setfont(4); kn_hot ? TC(1331, 468, fpct(slider22)); touch(21, "MIX", fpct(slider22));
setk(23, knob(22, 1411, 400, 25, slider23, -24, 12, 0, 0, 0));
cink(); gfx_setfont(3); TC(1411, 446, "OUTPUT"); gfx_setfont(4); kn_hot ? TC(1411, 468, fdb(slider23)); touch(22, "OUTPUT", fdb(slider23));

screw(18, 20); screw(18, 500); screw(1482, 20); screw(1482, 500);

// ? pop-up: design credit and the manual
hlp ? (
  gfx_r = gfx_g = gfx_b = 0; gfx_a = 0.62; gfx_rect(0, 0, gfx_w, gfx_h); gfx_a = 1;
  col(0.11, 0.11, 0.13); R(520, 170, 460, 170);
  col(0.88, 0.38, 0.23); R(540, 214, 420, 1);
  gfx_setfont(3); col(0.95, 0.95, 0.93); TX(540, 188, "Design by JGWizrad.  © John Garden 2026");
  gfx_setfont(5); col(0.91, 0.70, 0.23); TX(540, 230, "https://www.gardenfx.uk/");
  col(0.85, 0.84, 0.82); TX(540, 256, "Manual - https://www.gardenfx.uk/manual/gfx-gate.pdf");
  col(0.52, 0.51, 0.49); TX(540, 300, "Click anywhere to close.");
);
pcap = mouse_cap;