L-system tree · particle-1

Let me look at the directory first.

Design plan:

L-system grammar:
axiom: "X"
rules: X -> F[+X]F[-X]+X ; F -> FF
angle 22.5 degrees. Generation 1..5.

Interpret with turtle, draw progressively: build segment list with order/index; grow animation reveals segments over time based on a global progress. But to keep child branches attached to parents during sway, better approach: draw tree recursively from a structure with per-node depth, angle, length, apply sway rotation relative to parent, and animate "growth" via each segment's local growth fraction. Sway applies rotation at each node based on time and depth/height.

Implementation:
1. Parse L-system string into a tree structure: nodes with children lists. Turtle interpretation building a tree of branch segments: stack stores current tip index. Each F creates a segment from current position (in local turtle coordinates) to new position, with direction angle relative to parent's direction and length. Store as node {parent, angle (relative rotation), length, depth, order}.

Then draw recursively starting at base with cumulative absolute angle, adding wind sway: sway offset = windAmp * (depth factor) * sin(time + pathHeight...). Rotate relative angle plus sway delta. Use p5 drawing with translate/rotate recursion to accumulate.

Growth animation: each node has a "birth" time order proportional to its order (index in expanded traversal) or based on depth. Simpler: growth progress g (0..1) mapped to number of revealed segments; each segment reveals as scale fraction. Then tips grow. To have smooth, use per-node start = index/(total) with a slight transition; growth duration ~ 2.5s. Segment drawing: draw full length * clamp((g - start)/span). Since each node is drawn relative to parent using translate along its direction and rotate; using a partial length, child would need to attach at parent's tip — parent's grown length determines where children start. Simpler: hide children until parent fully grown (start times sequential by order ensures that since children come after parents in the traversal order). So draw node at translate(0, -length) after rotating; children are relative to the tip. If node's grown fraction < 1, just draw partial and skip children. Since child start >= parent start + span, parent full when child appears. Good.

Leaves at branch tips: small procedural leaf shapes drawn when depth >= some level and growth complete near tips.

Scaling: compute maximum radius/extent from expanded tree in local coords, then fit to canvas via scale factor. Or normalize total length. Compute bounding box by simulating turtle positions; then scale to fit canvas with margins. Also the tree should be computed per generation on regrow. Compute after generating structure, using max absolute x and min y.

Sway must not cause clipping: leave generous margins (~20%).

Wind: per-node sway rotation = amp * sin(t*speed + node.seed) where amp depends on "distance from trunk"/depth & relative height. Also bend trunk slightly at base. Use rotation added to each node: relative sway = baseSway*(0.15 + 0.85*normalizedDepth) maybe. Careful: sway summing along chain gives large movement for tips — good.

Also add smooth interpolation of sway amplitude on growth.

Drawing: use p5 with a canvas sized to window (responsive). Background gradient drawn with canvas or p5 background plus subtle stars/particles. Style: dark blue-green night with glow? Or light parchment. Let's do a slightly dark teal gradient background with soft glow, branch color warm brown with tapering stroke widths, leaves green-ish or autumn. Use p5 drawingContext for gradient background.

Controls UI in HTML overlay: generation slider/segmented 1-5 buttons, Regrow button, progress indicator. Custom CSS.

Seeded randomness: use a deterministic PRNG so the shapes vary per generation but stable. Seeds per node from index.

Grammar:
axiom: "F"
rules: "F" -> "F[+F]F[-F]F"? That's classic but produces a bush. Let's do:
axiom: "X"
X -> "F[+X][-X]FX"
F -> "FF"
angle 24°. For gen 1: X -> F[+X][-X]FX ; then expanding X again. Similar to a known plant.

Bounds: gen 5 expansion may get large — X->F[+X][-X]FX doubles X count, so 2^5 = 32 tips, F doubling each generation... total F count maybe around a few thousand. Fine. Let's estimate with code later.

Actually to be safe compute counts. Let's just build and print.

Let me write the code.

Structure building:

function expand(axiom, rules, gen) iterate replacing chars.
segments tree parse:
let root = {children: [], angle:0, len:0, depth:0, index:0, grown?}
turtle state: {node, angle, depth}. stack. For each char:
- 'F': create child of current node with angle = random jitter? Keep exact grammar but add small procedural jitter for organic look (deterministic per index). len depends on depth maybe: base * 0.8^? Using uniform length causes explosion; L-system F->FF doubles length each gen which gets unrealistic. Standard practice uses constant segment length, with gen increasing total size. We fit to canvas anyway, so fine. Use length 1 for all, and taper width based on depth/index.

Hmm but with F->FF, at gen5 the trunk may be 16-32 segments long, and same length at tips — normal L-system look. Fine.

- '+': angle += theta; '-': angle -= theta (and jitter small).
- '[': push {node, angle, depth}; ']': pop.
Each F creates a child node with relative angle = currentAngle - parentAbsAngle... Simpler: keep absolute angle in turtle; node stores absAngle and parentAbsAngle; when drawing recursion we need relative rotation. Store relAngle = absAngle - parentAbsAngle. Then drawing: push, rotate(relAngle + sway), translate(0,-len)... Let's define draw in screen coordinates: base at bottom, using y-up convention: rotate(0) means up (negative y). p5 rotate positive = clockwise in screen. Node abs angle 0 = up. Drawing: rotate(relAngle + swayOffset); translate(0, -drawnLen) — but children drawn after translate need to be positioned at tip; if drawnLen < len, children hidden anyway. Use line from (0,0) to (0,-drawnLen) then translate(0,-len) for the children frame? If children hidden during growth of parent, we can translate by -len once full. Actually since children are skipped unless fraction >= 1, we can just translate(0,-len) always after drawing the line; but the line drawn only to -drawnLen. Fine — children drawn only when full.

Actually simpler: draw line 0,-len and only render children when growth reveals node. But partial reveal is nicer. Do: if f < 1 -> line to -len*f, no children. else line to -len, render children.

Sway: add sway rotation per node, and it accumulates down path because each level rotates; that gives children staying attached. Sway magnitude increases with depth (deeper = flexible): swayAmp(depth) = base * (0.3 + depth*0.25) but cap. With 32 levels could be huge; instead base on normalized depth (depth/maxDepth). And wind phase depends on depth and index.

Also add global slight trunk rotation at base.

Let's compute growth: prepare segments list in traversal order with start fraction. Use cumulative length-based progress maybe: total "growth units" = count of nodes; each node gets start = i/N * (1 - tail) ... Let's just assign start = i/N and span = 0.15. Then node is fully grown when progress >= start+0.15. Children start at greater i so they appear when parent full? Not necessarily: parent index i, child i+1, so parent full at (i/N+0.15) and child starts at i+1/N = i/N + 0.025 < parent full in N>~7. Slight overlap causes children drawn floating at parent's full-length tip while parent's line is shorter (drawn len = len*f of parent, and translate uses full len!). Fix: children's start = max(own, parent start + span). Simplest: make growth based on depth-based completion: node's threshold = index/N but ensure parent's threshold + span <= child's start. Instead use a monotone mapping: render only if progress >= node.start + span (fully). Set node.start = index/N * (1 - span)... children drawn at translate(0,-len) of parent which is the full tip; parent line drawn only when fully revealed. So condition: parent must be fully revealed. So child should only draw after parent's start+span. Set child.start = max(traversalStart, parentStart + span) computed recursively during build (parent known). Then reveal f = clamp((progress - start)/span).

With that, progress total time = max start + span. Progress driven by elapsed/duration.

Wind after growth: sway amplitude ramp = smooth growth maybe always active but scaled by min(1, progress). Leaves appear when growth > 0.95 near tips with fade.

Leaves: at leaf nodes (no children) draw a leaf: ellipse/rotated shape with color; but grass? Use small leaf shapes drawn as bezier curves. Draw at tip with flutter.

Colors: branch color gradient from dark brown at trunk to lighter at tips; use lerpColor based on depth fraction. Background: vertical gradient dark #0b1a18 to #16202b, ground glow. Maybe add subtle radial glow behind tree, and little floating particles.

Let's fit: after building, compute bounding box of tips in local coords (angle 0 up, y negative). Compute minX, maxX, minY (most negative), plus branch length. Scale = min((W-2*margin)/(maxX-minX), (H - 2*margin)/(maxY - base?)) Actually tree extends from base upward: height = -minY. width = maxX-minX. scale = min(availW/width, availH/height). Base position at (cx - centerX*scale, baseY).

Sway increases width — margin 15% handles.

Also need max depth for sway normalization.

Canvas resize: recompute layout on windowResized, but keep tree structure. Compute base transform each draw from stored bounds.

For rendering crisp, use strokeWeight taper: weight = map(depthFraction, 0, 1, 8, 1) * scale-ish? In screen px, weights: trunk width 10 → 1.2 at tips. Use strokeWeight(Math.max(0.7, lerp(7,0.9, depth/maxDepth) * scaleFactor)) where scaleFactor relative to some reference. Simpler: since tree is scaled via transform, stroke would scale too if we set stroke before scale. Instead draw within push with the scale applied, and strokeWeight in local units, so weights scale along. Local branch length 1 → weight ~0.35 at trunk, 0.05 at tips. Good: strokeWeight(0.38 * (1 - 0.75*depth/maxDepth)). But line joins... fine.

Let me use local scale drawing: translate(baseX, baseY); scale(s). Then p5 line from 0,0 to 0,-len.

Also round caps: strokeCap(ROUND).

Particles: skip or minimal — fireflies drifting. Keep simple with deterministic sin positions.

UI: top-left panel with title "L-SYSTEM TREE", generation buttons 1..5, Regrow button, progress bar. Dark glass style. Also show rule text monospace: "X → F[+X][-X]FX,  F → FF,  θ = 24°".

Keyboard maybe: space regrow.

Now, code details for expand: bounds check length limit (e.g., max 100000 chars) to "bound grammar expansion". Gen max 5 so fine, still guard.

Let me estimate counts: X→F[+X][-X]FX: X count doubles; F: F count = 1 + 2? Each X produces 3 F's and 2 X's. Starting 1 X, after 5 gens X=32, F total? F_n = 3*F_{n-1}? Let's compute: F_{n} = F_{n-1}*2 (from F→FF) + 3*X_{n-1} + ... X_{n} = 2 X_{n-1}. X0=1,F0=0 → X1=2,F1=3; X2=4,F2=3*2+3*2=12; X3=8,F3=12*2+3*4=36; X4=16,F4=36*2+12=84; X5=32,F5=84*2+24=192. Total symbols ~ 5*32+192 = 352. Not huge. Maybe increase: use X→F[+X]F[-X]+X? That gives fewer. 352 segments at gen5 is reasonable but tree might look sparse-ish. Try X→F[+X][-X]FX with F→FF gives branching bush. Could use a richer rule: X → F[+X]F[-X]+X ; F → FF. Then F_n = 2F_{n-1} + 3 X_{n-1}: X1=1? X0=1 → X1=1, F1=2... that doesn't branch from initial X. Let's test gen1: "F[+X]F[-X]+X" gives main stem plus 2 branches. Gen2 expands those X's: adds branching further. That's a classic tree. X count stays 1 per branch... Actually each X gives one X in the main continuation, so X count constant = 1? No: X → F[+X]F[-X]+X produces 3 X's? Let's see: characters X appear 3 times: [+X], [-X], +X. Yes 3. So X_n = 3^n. Gen5 = 243 X, F count = 2 per X plus... F_n = 2X_{n-1}*... Total nodes ~ 2*(3^5) ≈ 500. Fine.

Compare visual: classic Fernandez tree. Let's use angle 25°.

I'll implement and screenshot.

Growth timing: node depth determines pacing? Use traversal index (DFS) which grows one branch fully before another — looks like the tree sprouting sequentially. Better: interleave by depth so all branches grow level by level? L-system traversal order DFS: it'll grow trunk to a tip, then next branch. Actually DFS from root: main trunk F's then branch... The visual would be a bit linear. Alternative: order nodes by depth (BFS) so whole tree grows outward in layers — looks more like a growing tree. But then parent full requirement: within BFS, parent depth < child depth, so parent start earlier. Assign start by BFS layer: layer = depth, duration layers. f per node = clamp((progress*(layers) - depth)/1,0,1)? With trunk at depth 1. Then all nodes at same depth appear simultaneously — nice level-by-level growth. Let's do that: total layers = maxDepth. progress p (0..1) → layerProgress = p*maxDepth; each node f = clamp(layerProgress - (depth-1), 0, 1). Parent (depth-1) full at layerProgress >= depth-1 and child starts exactly then. 

But branches appear with same length though varying F counts — fine.

Hmm with 30+ layers at gen5 this is fine; duration 3.2s.

Sway: apply when p>0.6 maybe; ramp amplitude with smoothstep((p-0.5)/0.4). Wind per node: swayAngle = amp * windStrength * (0.2 + 0.8*ndepth) * sin(time*1.1 + depth*0.45 + seed*2 + heightfactor). Use node phase = node.index*0.15 or based on position. Also secondary harmonic.

amp in radians: at deepest, e.g. 0.03 rad; each chain sums ~ yes tips move a lot. Trunk base amplitude 0.004.

Compute sway per node in drawing: relAngle + windSway(node). Where windSway = 0.02 * w *(0.1+nd) * sin(t*1.2 + ph) + 0.008*w*(...) * sin(t*2.3+ph*1.7). Multiply amplitude overall at depth normalized. Since accumulating down 30 levels each 0.02 rad gives total ~0.6 rad at tip which is too much. Use per-node amp ~ 0.02*(0.1+0.9*nd) but nodes at each depth are separate; sum over a chain of depth 30 with average ~0.012 → 0.36 rad = 20°, quite a lot but for tips maybe ok; leaves fluttering. But mid branches move too much. Reduce to 0.008 base: sum ~0.14 rad ≈ 8°. Good. Plus base trunk sway 0.01.

Let's write code now. Also handle p5 instance? Use global mode with setup/draw.

Canvas full window. Controls overlaid HTML.

Deterministic per-node jitter: use hash function from index: pseudo random from sin.

For leaves: draw at leaf nodes (children.length===0) always? In L-system tree some interior branches end with F tips. Leaf nodes = no children. Draw 2-3 leaflets with slight angle oscillation. Leaf size relative local units ~0.25? Branch length is 1 local unit; leaves maybe 0.5 length. Make leaf shape with bezier: beginShape CURVE.

Colors: leaf colors: spring green #8fd18a, #b7e08a, #6fbf73 with alpha. Branch: lerp from #6a4a32 (dark) to #a8815f. Background: depth gradient #071312 → #0d2321 with glow ellipse behind tree (#1b3b34). Maybe add moonlight.

Also add subtle vignette via radial gradient overlay drawn with canvas ctx.

Let's write the file.

Progress percentage display.

Generation change → regrow: rebuild structure with generation, reset growth start time.

Add Regrow button and buttons for gen. Regrow with same gen restarts growth.

Also add "wind" toggle? Not needed.

Let me write.

const cfg = {axiom:'X', rules:{X:'F[+X]F[-X]+X', F:'FF'}, angle:25};

Wait axiom X with rule X → F[+X]F[-X]+X: F→FF doubles segment. Gen 1 tree: trunk F, branch +X, F, branch -X, +X. Segments: only F's drawn; X not drawn. At gen1: "F[+X]F[-X]+X" → 2 F segments plus branch stubs of X (no segments). So gen 1 is thin. Better axiom 'X' but interpret X as drawn too? Common convention draws X as segment. Alternatively axiom 'F' and rules F → F[+F]F[-F]+F? That has no F doubling; gen5 gives 3^5 nodes ≈243 segments, each F one segment of same length, structure similar. Then branches all length equal — looks okay-ish.

Better: use axiom "F", rules: F -> FF[+F]F[-F]+F? Hmm.

Let's use: axiom 'X', rules: X → F[+X]F[-X]+X, F → FF, and interpret X as a segment too (draw X as branch with length 0.85?). Then gen1: X root draws a segment, etc. Actually standard practice draws both F and X as lines. That gives fuller tree. But then doubling F leads to long segments in middle. Hmm, F→FF makes trunk long lines, which is natural (thicker longer trunk). With taper by depth, and lengths equal per segment... the trunk at gen5 uses many F segments of length 1 while tips are length 1 too — visually balanced because taper handles thickness.

I'd rather have varying length: In local coordinates, treat each symbol segment length = 1 (both F and X). Since gen1 counts small, gen1 tree tiny structure (few segments) but scaled to fill canvas → chunky short tree? With 4 segments scaled to full canvas it'd look weird (huge blocks). Better to keep a fixed world scale per generation such that generation 1 is smaller? Requirement says whole tree visible at every generation — fit-to-canvas achieves that. Generation 1 will be a crude few-branch tree, acceptable and expected from L-systems (it visibly shows different branching structure). But scaling a 4-segment tree to fill the canvas makes massive thick branches. Could limit scale: scale = min(fitScale, someMaxScale) where max generally fit... Fit is needed for gen5. Hmm gen1 fit → big. Keep stroke width in absolute screen px rather than scaled local: compute branch thickness from depth but in screen px: weight = map(depthNorm,0,1, 9, 1.2) * (scale/fitScale5?) ... Simpler: compute weight in local units but relative to tree height rather than uniform: localWeight = 0.012 * treeHeightLocal? Let's do: base thickness in local units proportional to total height: trunk weight = treeHeightLocal * 0.012; tip = *0.0015. Since tree is scaled to fit, trunk onscreen ≈ heightPx*0.012 ≈ 10px. That's independent of gen. 

Lengths: use per-symbol length 1 for both.

Axiom 'X', gen1 gives "F[+X]F[-X]+X": draws 5 segments (2 F + 3 X) with 2 side branches. Fine for gen1. Gen5 ~ hundreds. Good.

Let me verify node count gen5: X_n=3^n=243, F_n = 2*X_{n-1} + 2*F_{n-1}? X→F[+X]F[-X]+X: 2 F's per X. F→FF: 2 F per F. F_n = 2F_{n-1} + 2X_{n-1} = 2F_{n-1}+2*3^{n-1}. F0=0. F1=2, F2=4+6=10, F3=20+18=38, F4=76+54=130, F5=260+162=422. X5=243. Total 665 nodes. Fine, ~665 line calls per frame plus leaves. OK.

Max bounding: could be very large in local units; compute exact bbox via turtle simulation (accumulate positions) — same as building nodes. Compute min/max of node tips.

Depth: could be up to ~? Each then F→FF adds 2, branches... maybe depth 40. Fine.

Let's write drawing recursion:

function drawNode(n, t, wind, p) {
  const f = constrain(layerProgress - (n.depth-1), 0, 1) // but ensure... 
  ...
}

Actually f per node same for all at depth — do f = clamp(gp - (n.depth-1),0,1) where gp = progress * maxDepth. If f<=0 skip. Also skip drawing children if f<1.

Rotation: push(); const nd = (n.depth-1)/max(1,maxDepth-1); const sw = wind * (0.35+0.65*nd) * (0.006*sin(t*1.15+n.phase+nd*2.0) + 0.003*sin(t*2.37+n.phase*1.6)); rotate(n.relAngle + sw);
Then stroke weight based on nd, line(0,0,0,-len*f). translate(0,-len). Render leaf if leaf and f==1 and progress near end? Leaves on tips: draw if node has no children and progress > 0.75 with fade. Leaves drawn at n=... inside node after translate(0,-len) maybe at tip (0,0) after translate. Draw leaves before children (none for leaf).

For non-leaf nodes, no leaves. But many tips are X ends — leaf nodes have no children. Good.

Also add small twigs? fine.

Wind handled with time from millis.

Colors: per depth lerp between trunk color and tip color, maybe also darken at bottom.

Glow: draw background gradient using ctx each frame (create once per resize via drawingContext.createLinearGradient each frame is okay but slowish; create in setup/resize and store). Simpler: draw with p5 background then a radial glow with fading ellipse loops? Use canvas gradient cached.

Let me do: in draw, if bgGrad null or W changed, create gradient. Then drawingContext.fillStyle = bgGrad; fillRect.

Also moon glow ellipse with p5.drawingContext radial gradient cached.

Fireflies: 40 particles drifting with sin, drawn as small glowing circles, time-based.

UI HTML:

<div id="ui">
 <h1>L-SYSTEM TREE</h1>
 <div class="rules">X → F[+X]F[-X]+X · F → FF · θ 25°</div>
 <div class="row" id="gens">buttons 1-5</div>
 <button id="regrow">Regrow</button>
 <div class="prog"><span id="bar"></span></div>
 <div class="hint">space = regrow</div>
</div>

Style with glassmorphism. Use system font stack.

Progress bar wider; fills during growth.

Now write code carefully.

Also generation restart: choose gen -> startGrowth(gen) sets state.gen, builds nodes, resets growthStart, maxDepth, bounds, scale computed in layout().

Layout: compute on draw each resize or after build: use windowWidth/Height.

Fit: tree local bbox: nodes tip coords recorded during build (x,y where y negative up). minX,maxX,maxY(top), base at 0,0. Width = maxX-minX (+ margin for leaves). Height = -minY.

s = min((W*0.86)/(width+2), (H*0.84)/(height+1)). Also cap? no.

baseX = W/2 - ((minX+maxX)/2)*s; baseY = H*0.94 (ground line).

Draw ground glow ellipse at baseY.

Sway width extra accounted by margin 0.86/0.84.

Now code.

Local weight: trunkW = heightLocal*0.012? leaves? Let's compute w = lerp(0.016, 0.0025, nd) * max(8, heightLocal*?) hmm. Simpler: local weight based on distance from base in local units: trunk weight = 0.012 * heightLocal, tip weight = 0.0015*heightLocal. Because heightLocal varies, onscreen trunk ≈ heightPx*0.012.

Actually onscreen trunk width = localWeight * s. s = fit height = 0.84H/heightLocal → onscreen = 0.012*heightLocal*0.84H/heightLocal = 0.01H ≈ 8px on 800. Good.

Leaves size local: 0.02*heightLocal? Onscreen 0.02*0.84H ≈ 13px. ok.

But careful: heightLocal varies wildly by generation. Using heightLocal-relative everything keeps consistent screen size. Good.

Implement.

Wind: after full growth, amplitude ramp should be full always (even during growth slight). wind = smoothstep growth maybe min(1, progress*1.2). Fine.

Write the file now.

Detailed code:

let cfg = {axiom:'X', rules:{'X':'F[+X]F[-X]+X','F':'FF'}, angle:25};
let gen = 4 default maybe 4 (nice). Requirement control 1..5. Default 4.

build(gen):
 const s = expand(...); guard length 20000.
 const nodes = []; const root = {children:[], relAngle:0, depth:0, len:0};
 stack = []; let cur = root; let ang = 0; let idx = 0;
 for ch:
   if '+' ang += rad; if '-' ang -= rad;
   if '[' push {cur, ang}; if ']' pop.
   if ch==='F'||ch==='X': create node {parentAngle: ang - baseAngleOfCur}. Need cur's absolute angle. Store absAngle on node. root.absAngle=0.
   node = {relAngle: ang - cur.absAngle, absAngle: ang, depth: cur.depth+1, index: idx++, children: [], parent: cur}; cur.children.push(node); cur = node; position update: pos.x += sin(ang), pos.y -= cos(ang). Store tip pos.
   Small jitter: ang += jitter? Jitter would change turtle angle permanently — apply deterministic jitter added to node relAngle only (visual) plus subsequent geometry? To keep bbox accurate, jitter relAngle slightly and also update ang accordingly so pos matches. Let's apply jitter to ang when creating node: jit = (hash(idx)-0.5)*angle*0.06; node angle uses ang (already including jitter). Then set ang to that. Fine.

Note: interpreting X as segment: yes.

Also to make it look organic, length varies with depth? All len 1. Taper via weight, plus maybe length scale by depth: len = 1 * (0.97^depth)? That shortens tips → more natural taper. But F→FF doubling at trunk... let's use len = Math.pow(0.93, depth) maybe tips tiny. With depth 40 → 0.055. Hmm scale differences. Let's do len = 1 - 0.012*depth min 0.35: depth 40 → 0.52. Slight taper. Good enough. Actually to compute bbox need to use len per node in pos update.

maxDepth computed.

After build compute bounds over tips and also base (0,0).

startGrowth: growthStart = millis(); state.progress = 0.

draw:
 clear bg, stars/fireflies, compute progress = min(1, (millis()-growthStart)/DURATION) with DURATION = 2600 + maxDepth*40? Use 3200 for gen5? level-based: layers grow at rate: total duration 3.2s constant.

 if p>=1, progress displayed 100%.

 ground glow.

 push translate(baseX, baseY) scale(s)
 drawNode(root's children...) — root has children array; iterate root.children with drawNode.

function drawNode(n) { const f = constrain(gp-(n.depth-1),0,1); if(f<=0) return;
 push(); const nd = clamp((n.depth-1)/(maxDepth-1),0,1);
 const ph = n.index*0.7 + n.depth*0.35;
 const sway = wind * (0.25+0.75*nd) * (0.007*Math.sin(t*1.1+ph) + 0.0035*Math.sin(t*2.3+ph*1.7+1.3));
 rotate(n.relAngle + sway);
 stroke(branchColor(nd)); strokeWeight(weightFor(nd)); line(0,0,0,-n.len*f);
 translate(0,-n.len);
 if (f>=1) { for children drawNode(c); if (n.children.length===0 && progress>0.55) drawLeaf(nd, ph); }
 pop();
}

Leaf at local (0,0) after translate. Leaf drawn with rotate based on sway flutter and shape.

Wait: drawing child lines while parent f<1? we only descend if f>=1. But parent's line drawn fully when f>=1, good.

However with layer-based growth, when f reaches 1 for depth d, next depth starts at gp = d. GP = progress * maxDepth. So progress needed for depth d full = d/maxDepth. Depth max completes at 1. Good.

leaf fade: leafAlpha = constrain((progress-0.5)/0.5,0,1)*255.

Root node depth 0 with len 0 — skip draw; just iterate children.

Leaf shape: draw as ellipse cluster rotated:

push(); translate(0,0); rotate(flutter); fill(leafColor); noStroke(); beginShape with bezier: use ellipse(0,-leafLen*0.4, leafW, leafLen) rotated? Simple: draw two ellipses angled ±0.5 rad about the branch direction. Let's do: rotate(-0.6 + flutter) then ellipse(leafSize*0.5, 0, leafSize, leafSize*0.45) etc. Actually orientation: branch direction is up (negative y). Leaves pointing outward:

for (k of [-1,1]) push(); rotate(k*0.7 + flutter*k); fill; ellipse(0, -leafSize*0.55, leafSize*0.55, leafSize*1.0); pop();

That places leaf elongated along local y.

Color variation deterministic by index.

Also a few flowers/berries? skip.

Fireflies: draw before tree with additive glow: fill(180,255,200,alpha) small circles + bigger faint.

Also add star/mote particles in bg maybe subtle.

Let's code the HTML/CSS/JS.

Be careful about stroke color per-depth: branchColor(nd): lerpColor(color(92,62,44), color(196,160,120), nd). Leaves gradient color.

Add subtle shadow/darkening near base.

Time budget 15 min — write now.

Also note p5 global functions: use windowWidth/windowHeight.

For canvas: createCanvas(windowWidth, windowHeight) in setup, pixelDensity(min(2, displayDensity())).

Resize: windowResized -> resizeCanvas; invalidate bgGrad.

UI update: progress bar width set each frame via el.style.width. Use requestAnimationFrame? p5 draw fine. Throttle text updates.

Buttons: gen buttons active state; click → setGen. Regrow → startGrowth(gen).

Also space key → regrow.

Let's write.

Also check "Sampling wind motion" verification: use browser motion tool maybe.

Write index.html.

Let's test in browser. Note p5 global mode requires setup/draw defined before loading? p5 in global mode waits for window load typically; functions defined after script tag in body should be fine (p5 checks on window ready). Let's inspect.

Growth at 3%. Let's screenshot after some time to see the grown tree.

The tree looks nice but somewhat sparse/asymmetric — branches lean right heavily and the tree occupies upper portion only with lots of empty space at left. Bounds fitting handles width, but because tree is asymmetric, center offset puts it right of panel. That's fine but there's a huge empty left; maybe position base at 55% of width. Also the tree shape is lopsided — asymmetric is natural. However several branches get cut? No, it fits.

Improvements:
- Base slightly right (cx = W*0.54) to leave room for panel? It's currently centered on bounding box, panel overlaps empty space. Fine.
- Trunk is thick and bare for a long stretch; leaves only near tips. That's ok, looks like a young tree.
- The tree seems to only occupy upper 2/3 with much vertical empty near bottom? Actually trunk from y=760 to y~390 — okay.

Maybe make tree fuller: default generation 5? Also could add more leaves and small twigs. Let's check gen 5 and gen 1, and growth animation and wind motion. Also check clipping at gen5 due to sway.

Let's test gen5 screenshot.

Gen5 looks a bit lopsided (right side heavy) but tree-like. Could improve symmetry by reducing jitter? The asymmetry comes from grammar asymmetry already. Actually X → F[+X]F[-X]+X is asymmetric by design. It looks fine.

But the canopy is dense and top-heavy. Slight issue: the trunk bare lower half. Acceptable.

I'd like to improve centering horizontally (bounding box includes leaves? No leaves extend beyond bounds used for fit). Bounds use tips only; leaves extend beyond by ~0.02*H; margin 0.84/0.82 handles.

Now check gen 1 and 3 quickly, plus wind motion. Let me check motion frames to verify sway and parent-child attachment.

Motion works — canopy sways visibly while trunk stays. Tree attaches fine.

Concern: tree is quite lopsided to right; unused left space. Also the tree's default 4 looked similar. It's okay but could be nicer with a more balanced grammar. Also the lower trunk is bare (no side branches until high up). Could use default gen 5 and maybe a second rule to add branching lower. The requirement doesn't demand aesthetics beyond reasonable.

Maybe improve centering: shift cx so tree is centered within available area right of panel? Panel at left 22..296 px; available area center = (296+W)/2 ≈ 748 for 1200. My tree's bounds center appears at x≈600 currently; bounding box fit ensures bbox centered at W/2 = 600 but visually the tree's mass is right-heavy because leaves at right. Move base to W*0.52? Actually the bounding box center is 600; the tree base is at x≈573. Slight shift right would balance visual mass. Not crucial.

One improvement worth doing: lower branches. Since the grammar adds branches at each X expansion, branches happen at deeper levels only, producing a tall bare trunk. Add a rule modification? E.g., axiom "X" rule X→F[+X]F[-X]FX and F→FF... that also branches similarly.

Could reduce bare trunk by applying length variation per depth more strongly? Not needed.

Let me test gen 1 and gen 3 briefly to verify restart and different structure, and check that hover/click of gen button works. Also check growth mid-way for parent-child connection with partial growth — take screenshot ~1.5s after regrow.

Growth starts at bottom (trunk). Good. Take screenshot mid-growth in ~1.5s.

Gen3 tree visible with distinct structure and leaves attached only at tips. Growth finished already (3400ms elapsed by screenshot). Fine.

Observations: The tree is right-leaning and there's dead space left. Also trunk bare for lower 45%. It's acceptable, but I could improve the balance by adjusting the grammar to be symmetric-ish: use X → F[+X]F[-X]FX? Hmm the leaning comes from the +X continuation bias. Alternative rule: X → F[+X][-X]FX (symmetric) with jitter still creates asymmetry but balanced. Let's test quickly whether it looks fuller/balanced. Also F → FF makes branch segments long.

Try grammar X → F[+X]F[-X]FX: X count doubles (2 per X), F count = 3 per X. Gen5: X5=32, F: F_n = 2F_{n-1} + 3*X_{n-1} = ... F0=0, X0=1: F1=3, X1=2; F2=6+6=12,X2=4; F3=24+12=36,X3=8; F4=72+24=96,X4=16; F5=192+48=240,X5=32. Total 272 nodes — less dense than current 665. Current is denser. Keep.

The lopsided look: because trunk continues with +X branches to the right mostly. It looks natural-ish. I'd rather center the visual mass better and reduce bare trunk. A simple improvement: make lower trunk a bit shorter by scaling length slightly increasing with depth? Actually the bare trunk comes from few X expansions at lower levels — inherent.

Alternatively use default gen 5 which is fuller. Change default to 5? Requirement says control 1-5; default any. Gen5 was fuller. But gen5 screenshot has right-side heavy mass and left top sparse. Fine.

Maybe shift base x so canopy centered: set cx = W/2 - bboxCenter*s + offset? bbox is centered at W/2 already, which leaves base left of center. Visual bulk to right. Shift base right by 6% W. Let's just use cx = W/2 - centerX*s + W*0.02? Small improvement, marginal. I'll leave.

One more important check: gen1 visibility and regrow via button. Also check no clipping for gen5 during max wind (screenshot showed margin ~50px top; sway displaces maybe 15px, fine).

Check gen1.

Gen1 works with distinct branching. Colors tip branches: leaves at tip only. But the top two tips lack a final segment? Gen1 renders 5 segments; branches look fine.

There's a slight issue: the branch thickness at gen1 is thin, because height local is small (tree short) so weights smaller relative to screen? Trunk measured 8px – okay.

Everything works. One improvement I want: the tree at gen4/5 leans right and is centered around x=600 but with empty left space behind panel; acceptable.

Optional polish: add a soft glow around leaves and branch tips? Not necessary.

Check console errors: none.

Also check Regrow button restarts (already saw gen changes restart). Space key works via keydown.

One thing: leaf alpha uses `base.setAlpha` on a color from lerpColor; fine.

Verify gen5 again after changes? No changes made. Final file is saved. Maybe improve visual balance slightly by shifting view center left? Actually the tree bbox center at 600, but the panel at left takes space. Could shift right to ~640. Let me leave it.

One potential correctness point: on window resize, layout uses current width/height, works.

Another: `state.nodes` unused except storage. Fine.

Potential issue on first load: p5 calls setup which calls startGrowth before fonts loaded etc. Fine.

I want to confirm growth animation shows progressive connection mid-way (screenshot earlier at 1% only trunk). Let me do a quick check at ~2s by clicking gen 5 and screenshotting in ~1.2s, to verify branches partially grown and attached.

Gen5 tree looks nice and fills canvas with margin. Leaves cluster at tips, tree reads as a tree. There's a bit of overlap with the UI panel? The canopy starts at x≈390, panel ends x≈293 — no overlap.

Growth restarts correctly. Wind motion verified earlier.

Possible improvement: tree's canopy leaves look like clumps — nice.

One concern: the screenshot at 1.5s showed 100% already because p5 draw stalls/hidden tab? The growth took 3400ms but screenshot after 1.5s showed 100%. Hmm — perhaps millis elapsed during the click interaction or browser frozen. Actually the prior click at Gen5 gave 1% then sleep 1.5 → 100%? That is odd. Maybe the harness captures screenshot after additional delay. Earlier gen3 sleep1.4 → 100% too. Not a functional issue, but growth duration appears short in wall clock. Timing tool may add delay. Progress bar visibly moved from 1% to 100%, so animation is running.

Let me verify actual growth duration by checking progress at a precise moment using inspect of DOM after a short delay via bash sleep 0.8 maybe. Could use browser type? Simpler: use evaluate? Only inspect returns DOM. Could inject nothing. It's likely timing of tool calls includes image generation delay (~2s). Fine.

Final assessment: Works. Maybe shorten duration slightly? 3.4s is fine.

One last thing: ensure default 4 on load and no external requests. Script only local p5. Good.

I'll make one small visual improvement: reduce jitter? No, keep.

Done. Report.