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Synthwave sunset · minimax-m3
Create an animated synthwave sunset: a glowing gradient sun with scanlines setting over an infinite neon grid that scrolls toward the viewer, with a starfield and a reflected horizon.
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user
Create an animated synthwave sunset: a glowing gradient sun with scanlines setting over an infinite neon grid that scrolls toward the viewer, with a starfield and a reflected horizon.
assistant
thinking
The user wants me to create an animated synthwave sunset as a single-page web app in one HTML file. Let me plan this out:
1. **Glowing gradient sun with scanlines** - A circular sun on the horizon with a gradient (yellow/orange/pink/purple) and horizontal scanlines cutting through it
2. **Infinite neon grid scrolling toward viewer** - Classic synthwave perspective grid, magenta/cyan, scrolling toward camera
3. **Starfield** - Small twinkling stars in the sky
4. **Reflected horizon** - The sun reflects in the ground/grid area
I'll use Canvas 2D for this. Let me think about the approach:
- Use a single canvas
- Sky gradient background (deep purple to orange/pink)
- Stars drawn as small points, maybe with twinkle effect
- Sun: gradient circle with horizontal scanlines overlay
- Sun reflection: mirrored/inverted version fading down
- Grid: perspective grid lines using math (vanishing point), scrolling
- Mountains maybe? Could add distant mountains for depth
Let me code this up carefully:
```javascript
// Setup canvas
const canvas = document.getElementById('c');
const ctx = canvas.getContext('2d');
let W, H;
function resize() { W = canvas.width = innerWidth; H = canvas.height = innerHeight; }
addEventListener('resize', resize); resize();
// Stars
const stars = Array.from({length: 200}, () => ({
x: Math.random(),
y: Math.random() * 0.6, // only upper sky
r: Math.random() * 1.2 + 0.2,
tw: Math.random() * Math.PI * 2
}));
// Grid
let gridOffset = 0;
```
For the grid, I'll use perspective projection:
- Horizon line at, say, 55% of height
- Vanishing point at center of horizon
- Horizontal lines spaced exponentially (closer = bigger gap)
- Vertical lines converging to vanishing point
Let me think about the sun:
- Center around horizon level
- Multiple stops: white-yellow at top, then yellow, orange, pink, magenta at bottom
- Scanlines: thin horizontal dark bands across the sun
Let me also add some shooting stars occasionally for flair.
Here's my plan for the HTML structure:
- A single canvas filling viewport
- Maybe a subtle vignette
- Maybe some "scanline" overlay across whole screen for retro CRT feel
- Title text in synthwave font (using system fonts since no external)
Let me write this now. I'll be detailed and make it look really good.
Let me design the colors:
- Sky top: deep indigo/purple (#0a0033 or similar)
- Sky mid: purple/pink (#3a0d5e)
- Sky bottom (horizon): orange/pink (#ff6b3d)
- Sun: gradient yellow → orange → magenta → purple
- Grid: magenta/cyan neon (#ff00ff or #00ffff)
- Sun scanlines: dark bands
I'll add:
- Mountains silhouettes
- A palm tree silhouette or two on the sides
- Lens flare / glow effects
- Maybe a chrome text title
Actually let me keep it focused on the requested elements: glowing sun with scanlines, infinite neon grid, starfield, reflected horizon. I'll add subtle mountains for depth but not overdo it.
Let me write the code now:
```html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Synthwave Sunset</title>
<style>
* { margin: 0; padding: 0; box-sizing: border-box; }
html, body { width: 100%; height: 100%; overflow: hidden; background: #000; }
canvas { display: block; position: absolute; top: 0; left: 0; }
.vignette {
position: absolute;
inset: 0;
pointer-events: none;
background: radial-gradient(ellipse at center, transparent 40%, rgba(0,0,0,0.6) 100%);
}
.crt {
position: absolute;
inset: 0;
pointer-events: none;
background: repeating-linear-gradient(
0deg,
rgba(0,0,0,0.15) 0px,
rgba(0,0,0,0.15) 1px,
transparent 1px,
transparent 3px
);
mix-blend-mode: overlay;
}
.title {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
color: #fff;
font-family: 'Impact', 'Arial Black', sans-serif;
font-size: clamp(40px, 8vw, 120px);
letter-spacing: 0.1em;
text-shadow:
0 0 10px #ff00ff,
0 0 20px #ff00ff,
0 0 40px #00ffff,
0 0 80px #00ffff;
pointer-events: none;
opacity: 0.9;
}
</style>
</head>
<body>
<canvas id="c"></canvas>
<div class="crt"></div>
<div class="vignette"></div>
<h1 class="title">SYNTHWAVE</h1>
<script>
// ... canvas code
</script>
</body>
</html>
```
Wait, the user didn't ask for a title. Let me focus on the animation itself. I might add a subtle title since it's a synthwave piece, but it's optional. Actually, let me add it because it completes the synthwave aesthetic. But I'll keep it subtle.
Actually let me re-read: "Create an animated synthwave sunset: a glowing gradient sun with scanlines setting over an infinite neon grid that scrolls toward the viewer, with a starfield and a reflected horizon."
So the elements are:
1. Glowing gradient sun with scanlines
2. Infinite neon grid scrolling toward viewer
3. Starfield
4. Reflected horizon
No title mentioned. I'll skip the title or make it very subtle. Let me focus on the visuals.
Actually, the title is part of the synthwave aesthetic and adds to it. I'll include a small one. But not required. Let me focus on the core.
Let me think about implementation details:
**Sky gradient**: vertical gradient from deep purple (top) to orange/pink (horizon)
**Stars**: small white points scattered in upper portion, with random twinkle (sine wave modulating alpha)
**Sun**:
- Position: center horizontally, sitting on horizon (so center at horizon line)
- Radius: ~25% of screen height
- Fill: vertical gradient from white/bright yellow at top to deep magenta at bottom
- Scanlines: horizontal stripes that appear as the sun "sits" on the horizon - typically the bottom half has visible scanlines
**Horizon line**: where sun meets grid
**Sun reflection**:
- Mirrored below the horizon
- Fades out as it goes down
- Maybe slightly distorted / wavy
**Grid**:
- Vertical lines converge to vanishing point at center of horizon
- Horizontal lines get closer together as they go further back
- Scrolling animation: horizontal lines move toward viewer (downward in screen space)
- Color: bright neon (magenta or cyan, or both)
- Glow effect via shadow blur or additive blend
**Mountains** (optional): dark purple silhouettes between sun and horizon
Let me code this:
```javascript
const canvas = document.getElementById('c');
const ctx = canvas.getContext('2d');
let W, H, horizon;
function resize() {
W = canvas.width = innerWidth;
H = canvas.height = innerHeight;
horizon = H * 0.58;
}
addEventListener('resize', resize);
resize();
// Stars
const stars = [];
for (let i = 0; i < 250; i++) {
stars.push({
x: Math.random() * W,
y: Math.random() * horizon * 0.95,
r: Math.random() * 1.3 + 0.2,
baseAlpha: Math.random() * 0.6 + 0.2,
twSpeed: Math.random() * 0.02 + 0.005,
twPhase: Math.random() * Math.PI * 2,
color: Math.random() < 0.3 ? '#ffd9f5' : '#ffffff'
});
}
let gridOffset = 0;
function drawSky() {
const grad = ctx.createLinearGradient(0, 0, 0, horizon);
grad.addColorStop(0, '#0a0024');
grad.addColorStop(0.3, '#1a0644');
grad.addColorStop(0.6, '#3a0e5e');
grad.addColorStop(0.85, '#a82570');
grad.addColorStop(1, '#ff5d3a');
ctx.fillStyle = grad;
ctx.fillRect(0, 0, W, horizon);
}
function drawStars() {
for (const s of stars) {
const alpha = s.baseAlpha + Math.sin(s.twPhase) * 0.3;
ctx.fillStyle = s.color;
ctx.globalAlpha = Math.max(0, alpha);
ctx.beginPath();
ctx.arc(s.x, s.y, s.r, 0, Math.PI * 2);
ctx.fill();
}
ctx.globalAlpha = 1;
}
function drawSun() {
const cx = W / 2;
const cy = horizon;
const r = Math.min(W, H) * 0.22;
// Glow
const glowGrad = ctx.createRadialGradient(cx, cy, r * 0.5, cx, cy, r * 2);
glowGrad.addColorStop(0, 'rgba(255, 100, 200, 0.4)');
glowGrad.addColorStop(1, 'rgba(255, 100, 200, 0)');
ctx.fillStyle = glowGrad;
ctx.fillRect(0, 0, W, horizon);
// Sun body
const sunGrad = ctx.createLinearGradient(cx, cy - r, cx, cy + r);
sunGrad.addColorStop(0, '#fff5b0');
sunGrad.addColorStop(0.3, '#ffd24d');
sunGrad.addColorStop(0.55, '#ff7a3a');
sunGrad.addColorStop(0.85, '#ff2d8c');
sunGrad.addColorStop(1, '#a82470');
ctx.fillStyle = sunGrad;
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.fill();
// Scanlines (only on lower half of sun)
ctx.save();
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.clip();
const scanStart = cy;
const scanEnd = cy + r;
const gap = 4;
for (let y = scanStart; y < scanEnd; y += gap * 2) {
ctx.fillStyle = 'rgba(0, 0, 0, 0.55)';
ctx.fillRect(cx - r, y, r * 2, gap);
}
ctx.restore();
}
function drawReflection() {
// Mirror of sun fading down
const cx = W / 2;
const cy = horizon;
const r = Math.min(W, H) * 0.22;
ctx.save();
const refGrad = ctx.createLinearGradient(0, horizon, 0, H);
refGrad.addColorStop(0, 'rgba(20, 5, 35, 0.7)');
refGrad.addColorStop(0.3, 'rgba(40, 10, 60, 0.85)');
refGrad.addColorStop(1, 'rgba(5, 0, 15, 1)');
ctx.fillStyle = refGrad;
ctx.fillRect(0, horizon, W, H - horizon);
ctx.restore();
// Draw reflected sun (upside down, fading)
// ... (after grid)
}
function drawGrid() {
const cx = W / 2;
// Draw ground
// ...
// Vertical lines
ctx.strokeStyle = '#ff2bd6';
ctx.shadowColor = '#ff2bd6';
ctx.shadowBlur = 8;
ctx.lineWidth = 1.5;
const numVert = 30;
for (let i = -numVert; i <= numVert; i++) {
ctx.beginPath();
ctx.moveTo(cx + i * 80, horizon);
ctx.lineTo(cx + i * 80 * 8, H);
ctx.stroke();
}
// Horizontal lines (perspective)
const speed = 0.5;
gridOffset = (gridOffset + speed) % 50;
for (let i = 0; i < 20; i++) {
const t = (i + gridOffset / 50);
const y = horizon + Math.pow(t / 20, 2) * (H - horizon);
ctx.beginPath();
ctx.moveTo(0, y);
ctx.lineTo(W, y);
ctx.stroke();
}
}
```
Hmm, the grid math is tricky. Let me think more carefully.
For the grid:
- Vanishing point at (cx, horizon)
- Vertical lines: from vanishing point spreading outward to bottom edges
- Horizontal lines: parallel to horizon but spaced in perspective
For perspective horizontal lines spacing:
- y(t) = horizon + (H - horizon) * f(t)
- For uniform spacing along the ground, f should be nonlinear
- If we parameterize by depth, line at depth d appears at y = horizon + (H - horizon) * d / (d + something)
- Common: y = horizon + (H - horizon) * i / (i + k) for some k
Actually a simple approach: use exponential spacing.
- Let line i be at depth proportional to exp(i)
- y = horizon + (H - horizon) * depth / (depth + depthAtHorizon)
Or simpler: use i^2 spacing
- y = horizon + (H - horizon) * (i/N)^2
For scrolling, we want the lines to move toward viewer, meaning new lines emerge from horizon and move down. So we need to animate the offset such that lines get denser as they come toward us (or move down further).
Let me use a different parameterization:
- t goes from 0 (horizon) to 1 (bottom)
- y(t) = horizon + (H - horizon) * t
- For uniform spacing in the depth direction (which is what we want for "infinite grid scrolling"), we want t to be nonlinear in some depth function.
If we say depth z is proportional to 1/(1-t), then as t→1, z→∞. Lines at equal z spacing would have:
t = 1 - 1/(1 + z)
y = horizon + (H - horizon) * z / (1 + z)
Or:
t = z / (z + k) where k is some constant
Let me try:
- depth goes from 0 at horizon to ∞ at bottom
- y = horizon + (H - horizon) * depth / (depth + d0)
where d0 is depth at horizon (some constant that determines "look")
Actually let me think of it as: in 3D, with camera at height H, looking at horizon level. Lines on ground at distance d appear at vertical pixel position:
- The angle below horizon = atan(H/d) (or similar, depends on FOV)
- For wide FOV, use: y = horizon + (H - horizon) * (1 - 1/(1 + d/d0))
So lines at uniform spacing d appear non-uniformly in screen pixels (closer = more pixels between lines).
For animation: imagine d increases over time. Each line moves outward (down in screen space) and a new line emerges at horizon when d wraps.
```javascript
let z = 0;
const dz = 0.01;
const zMax = 1;
function drawGrid() {
z += dz * dt;
if (z > 1) z -= 1;
// Draw lines at z = z, z+1, z+2, ...
for (let i = 0; i < numLines; i++) {
const depth = z + i; // depth in units
const t = depth / (depth + d0);
const y = horizon + (H - horizon) * t;
// ...
}
}
```
This is getting complex. Let me try a simpler exponential approach:
```javascript
// Line positions: y = horizon + (H - horizon) * 2^i / scale
// For i from 0 to N, with offset animated
const lines = [];
let offset = 0;
function drawGrid() {
offset = (offset + 0.005) % 1;
ctx.strokeStyle = '#ff2bd6';
ctx.lineWidth = 1.5;
ctx.shadowColor = '#ff2bd6';
ctx.shadowBlur = 10;
for (let i = -1; i < 25; i++) {
let v = i + offset; // 0 to N
if (v < 0) continue;
const t = Math.pow(v / 20, 2.2);
const y = horizon + (H - horizon) * t;
if (y > H) break;
ctx.beginPath();
ctx.moveTo(0, y);
ctx.lineTo(W, y);
ctx.stroke();
}
}
```
Hmm, let me use a cleaner formula. Actually:
The clean way: use perspective with depth d and a constant K:
y = horizon + (H - horizon) * d / (d + K)
For animation, set d = (frame * speed + i * spacing) and wrap when d exceeds some max.
```javascript
function drawGrid() {
const K = 15; // controls how "deep" the perspective looks
const spacing = 1; // depth units between lines
const totalDepth = 100;
let d = (frame * 0.02) % spacing; // current offset
while (d < totalDepth) {
const y = horizon + (H - horizon) * d / (d + K);
if (y > H) break;
drawHLine(y);
d += spacing;
}
frame++;
}
```
This should work nicely. The lines will appear at the horizon and move toward the viewer, getting closer together as they approach.
For vertical lines (the converging ones):
```javascript
function drawVertLines() {
const numLines = 25;
const spread = W * 1.2;
for (let i = -numLines; i <= numLines; i++) {
const xAtBottom = W/2 + i * (W / 12);
ctx.beginPath();
ctx.moveTo(W/2, horizon);
ctx.lineTo(xAtBottom, H);
ctx.stroke();
}
}
```
That looks good.
Now for the sun reflection, I'll do:
1. Draw ground (dark gradient from horizon to bottom)
2. Draw grid
3. Then overlay reflected sun: gradient (mirror of sun's gradient) that fades to transparent
4. Add slight horizontal "shimmer" lines in reflection
Let me also add mountains for depth. Just dark silhouettes between the sun and horizon line.
Actually, let me reconsider. The "reflected horizon" might mean the horizon is reflected - i.e., the sun appears both above and below the horizon, mirrored. This is a classic synthwave element.
So below the horizon, we should see the inverted reflection of the sun fading down through the grid. Let me make sure to do that.
I'll draw:
1. Sky gradient (top to horizon)
2. Stars
3. Mountains (silhouettes)
4. Sun (above horizon, with scanlines on lower portion)
5. Sun glow extending below horizon (slight reflection start)
6. Ground gradient (horizon to bottom)
7. Reflected sun (mirrored, faded with shimmer)
8. Grid lines (over the reflection, since it's a grid)
Let me write the full code now:
```html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Synthwave Sunset</title>
<style>
* { margin: 0; padding: 0; box-sizing: border-box; }
html, body {
width: 100%; height: 100%;
overflow: hidden;
background: #000;
font-family: 'Courier New', monospace;
}
canvas {
display: block;
position: absolute;
top: 0; left: 0;
image-rendering: optimizeQuality;
}
.crt {
position: fixed;
inset: 0;
pointer-events: none;
z-index: 10;
background: repeating-linear-gradient(
0deg,
rgba(0,0,0,0) 0px,
rgba(0,0,0,0) 2px,
rgba(0,0,0,0.25) 3px,
rgba(0,0,0,0) 4px
);
mix-blend-mode: multiply;
}
.vignette {
position: fixed;
inset: 0;
pointer-events: none;
z-index: 11;
background: radial-gradient(ellipse at center, transparent 50%, rgba(0,0,0,0.7) 100%);
}
.hud {
position: fixed;
bottom: 20px;
left: 50%;
transform: translateX(-50%);
color: #ff77d4;
font-size: 11px;
letter-spacing: 0.3em;
text-transform: uppercase;
z-index: 12;
text-shadow: 0 0 8px #ff2bd6;
opacity: 0.7;
font-family: 'Courier New', monospace;
}
</style>
</head>
<body>
<canvas id="c"></canvas>
<div class="crt"></div>
<div class="vignette"></div>
<div class="hud">// S U N S E T M O D E // 1985 //</div>
<script>
(() => {
const canvas = document.getElementById('c');
const ctx = canvas.getContext('2d');
let W, H, horizon;
function resize() {
W = canvas.width = innerWidth * devicePixelRatio;
H = canvas.height = innerHeight * devicePixelRatio;
canvas.style.width = innerWidth + 'px';
canvas.style.height = innerHeight + 'px';
ctx.scale(devicePixelRatio, devicePixelRatio);
horizon = innerHeight * 0.6;
}
window.addEventListener('resize', () => {
// Reset transform
ctx.setTransform(1, 0, 0, 1, 0, 0);
resize();
});
resize();
const w = () => innerWidth;
const h = () => innerHeight;
const horizonY = () => innerHeight * 0.6;
// Stars
const stars = [];
for (let i = 0; i < 280; i++) {
stars.push({
x: Math.random(),
y: Math.random() * 0.55,
r: Math.random() * 1.4 + 0.2,
baseAlpha: Math.random() * 0.5 + 0.4,
twSpeed: Math.random() * 0.04 + 0.01,
twPhase: Math.random() * Math.PI * 2,
color: Math.random() < 0.25 ? ['#ffd9f5','#ffe7a8','#bcefff'][Math.floor(Math.random()*3)] : '#ffffff'
});
}
// Mountains
const mountains = [];
const numMountains = 12;
for (let i = 0; i < numMountains; i++) {
mountains.push({
x: (i / numMountains) * 1.2 - 0.1,
h: Math.random() * 0.05 + 0.02,
w: Math.random() * 0.08 + 0.04
});
}
// Shooting stars
const shootingStars = [];
function spawnShootingStar() {
shootingStars.push({
x: Math.random() * w(),
y: Math.random() * horizonY() * 0.5,
vx: -3 - Math.random() * 4,
vy: 1 + Math.random() * 2,
life: 0,
maxLife: 60 + Math.random() * 40
});
}
setInterval(spawnShootingStar, 3500);
let lastTime = performance.now();
let gridZ = 0;
function drawSky() {
const grad = ctx.createLinearGradient(0, 0, 0, horizonY());
grad.addColorStop(0, '#06002a');
grad.addColorStop(0.25, '#180850');
grad.addColorStop(0.5, '#3c0d6c');
grad.addColorStop(0.75, '#8e1f74');
grad.addColorStop(0.95, '#e34a4a');
grad.addColorStop(1, '#ff8a3c');
ctx.fillStyle = grad;
ctx.fillRect(0, 0, w(), horizonY());
}
function drawStars(t) {
for (const s of stars) {
const tw = Math.sin(t * s.twSpeed + s.twPhase);
const alpha = s.baseAlpha + tw * 0.3;
ctx.fillStyle = s.color;
ctx.globalAlpha = Math.max(0.1, alpha);
ctx.beginPath();
ctx.arc(s.x * w(), s.y * horizonY(), s.r, 0, Math.PI * 2);
ctx.fill();
}
ctx.globalAlpha = 1;
}
function drawShootingStars() {
for (let i = shootingStars.length - 1; i >= 0; i--) {
const ss = shootingStars[i];
ss.life++;
ss.x += ss.vx;
ss.y += ss.vy;
const a = 1 - ss.life / ss.maxLife;
if (a <= 0) { shootingStars.splice(i, 1); continue; }
const grd = ctx.createLinearGradient(ss.x, ss.y, ss.x - ss.vx * 20, ss.y - ss.vy * 20);
grd.addColorStop(0, `rgba(255,255,255,${a})`);
grd.addColorStop(1, 'rgba(255,255,255,0)');
ctx.strokeStyle = grd;
ctx.lineWidth = 1.5;
ctx.beginPath();
ctx.moveTo(ss.x, ss.y);
ctx.lineTo(ss.x - ss.vx * 20, ss.y - ss.vy * 20);
ctx.stroke();
}
}
function drawMountains() {
ctx.fillStyle = '#0a0420';
for (const m of mountains) {
const baseY = horizonY();
const peakX = (m.x + 0.5) * w();
const peakY = baseY - m.h * h();
const w2 = m.w * w();
ctx.beginPath();
ctx.moveTo(peakX - w2, baseY);
ctx.lineTo(peakX, peakY);
ctx.lineTo(peakX + w2 * 0.6, baseY);
ctx.closePath();
ctx.fill();
}
}
function drawSun(t) {
const cx = w() / 2;
const cy = horizonY();
const r = Math.min(w(), h()) * 0.22;
// Outer glow
const glowR = r * 2.5;
const glow = ctx.createRadialGradient(cx, cy, r * 0.8, cx, cy, glowR);
glow.addColorStop(0, 'rgba(255, 80, 180, 0.45)');
glow.addColorStop(0.5, 'rgba(255, 50, 140, 0.15)');
glow.addColorStop(1, 'rgba(255, 50, 140, 0)');
ctx.fillStyle = glow;
ctx.fillRect(cx - glowR, cy - glowR, glowR * 2, glowR * 2);
// Sun body
const sg = ctx.createLinearGradient(cx, cy - r, cx, cy + r);
sg.addColorStop(0, '#fffbe0');
sg.addColorStop(0.2, '#ffe070');
sg.addColorStop(0.45, '#ffaa3a');
sg.addColorStop(0.7, '#ff4a8a');
sg.addColorStop(1, '#a01a8a');
ctx.fillStyle = sg;
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.fill();
// Scanlines on lower half
ctx.save();
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.clip();
const lineHeight = 3;
const gap = 4;
for (let y = cy; y < cy + r; y += lineHeight + gap) {
ctx.fillStyle = 'rgba(10, 0, 25, 0.6)';
ctx.fillRect(cx - r, y, r * 2, lineHeight);
}
ctx.restore();
}
function drawGround() {
const grad = ctx.createLinearGradient(0, horizonY(), 0, h());
grad.addColorStop(0, '#2a0540');
grad.addColorStop(0.3, '#150225');
grad.addColorStop(1, '#04000d');
ctx.fillStyle = grad;
ctx.fillRect(0, horizonY(), w(), h() - horizonY());
}
function drawSunReflection() {
// Mirrored gradient that fades down
const cx = w() / 2;
const cy = horizonY();
const r = Math.min(w(), h()) * 0.22;
// Reflection band on ground
const refY = horizonY();
const refHeight = h() * 0.45;
// Vertical fading mask
const fadeGrad = ctx.createLinearGradient(0, refY, 0, refY + refHeight);
fadeGrad.addColorStop(0, 'rgba(10, 0, 25, 0.55)');
fadeGrad.addColorStop(0.5, 'rgba(10, 0, 25, 0.85)');
fadeGrad.addColorStop(1, 'rgba(10, 0, 25, 1)');
// The reflection of sun (mirrored gradient)
const sg = ctx.createLinearGradient(cx, cy, cx, cy + refHeight);
sg.addColorStop(0, '#a01a8a');
sg.addColorStop(0.15, '#ff4a8a');
sg.addColorStop(0.35, '#ffaa3a');
sg.addColorStop(0.6, '#ffe070');
sg.addColorStop(1, '#fffbe0');
// Apply mask via global composite or careful rect
// Actually let's clip to sun-width column
ctx.save();
// Horizontal mask: only within sun's width
const hMask = ctx.createLinearGradient(cx - r, 0, cx + r, 0);
hMask.addColorStop(0, 'rgba(0,0,0,0)');
hMask.addColorStop(0.3, 'rgba(0,0,0,1)');
hMask.addColorStop(0.7, 'rgba(0,0,0,1)');
hMask.addColorStop(1, 'rgba(0,0,0,0)');
// Use globalCompositeOperation for vertical fade? No, simpler: use a clip + gradient with alpha
// Approach: draw a rect with the mirror gradient, then mask via a separate clip
ctx.beginPath();
ctx.rect(cx - r, cy, r * 2, refHeight);
ctx.clip();
// Apply horizontal taper
ctx.fillStyle = sg;
ctx.fillRect(cx - r, cy, r * 2, refHeight);
ctx.restore();
// Now apply horizontal taper via second pass with mask
ctx.save();
ctx.beginPath();
ctx.rect(cx - r * 1.3, cy, r * 2.6, refHeight);
ctx.clip();
// Vertical fade overlay (using 'destination-in' to remove)
ctx.globalCompositeOperation = 'destination-in';
const fade2 = ctx.createLinearGradient(0, cy, 0, cy + refHeight);
fade2.addColorStop(0, 'rgba(0,0,0,1)');
fade2.addColorStop(0.4, 'rgba(0,0,0,0.6)');
fade2.addColorStop(1, 'rgba(0,0,0,0)');
ctx.fillStyle = fade2;
ctx.fillRect(cx - r * 1.3, cy, r * 2.6, refHeight);
// Horizontal taper via mask
ctx.globalCompositeOperation = 'source-atop';
ctx.beginPath();
ctx.rect(cx - r * 1.3, cy, r * 2.6, refHeight);
ctx.clip();
const hMask2 = ctx.createLinearGradient(cx - r, 0, cx + r, 0);
hMask2.addColorStop(0, 'rgba(0,0,0,0)');
hMask2.addColorStop(0.2, 'rgba(0,0,0,0.5)');
hMask2.addColorStop(0.5, 'rgba(0,0,0,1)');
hMask2.addColorStop(0.8, 'rgba(0,0,0,0.5)');
hMask2.addColorStop(1, 'rgba(0,0,0,0)');
ctx.fillStyle = hMask2;
ctx.fillRect(cx - r, cy, r * 2, refHeight);
ctx.restore();
ctx.globalCompositeOperation = 'source-over';
}
function drawGrid(t) {
const cx = w() / 2;
const cy = horizonY();
const hh = h();
// Vertical lines (static)
ctx.strokeStyle = '#ff2bd6';
ctx.shadowColor = '#ff36c8';
ctx.shadowBlur = 8;
ctx.lineWidth = 1.2;
const numVert = 24;
for (let i = -numVert; i <= numVert; i++) {
if (i === 0) continue;
const xAtBottom = cx + i * (w() / 14);
ctx.beginPath();
ctx.moveTo(cx, cy);
ctx.lineTo(xAtBottom, hh);
ctx.stroke();
}
// Horizontal lines (animated)
const K = 12;
const speed = 0.04;
gridZ += speed;
const spacing = 1;
let z = gridZ % spacing;
let count = 0;
while (count < 40) {
const denom = z + K;
const yPos = cy + (hh - cy) * z / denom;
if (yPos > hh) break;
// Fade in intensity based on z (farther = fainter)
const intensity = Math.min(1, z / 4);
const alpha = 0.3 + intensity * 0.7;
ctx.strokeStyle = `rgba(255, 60, 200, ${alpha})`;
ctx.shadowColor = '#ff36c8';
ctx.shadowBlur = 4 + intensity * 8;
ctx.lineWidth = 0.8 + intensity * 0.8;
ctx.beginPath();
ctx.moveTo(0, yPos);
ctx.lineTo(w(), yPos);
ctx.stroke();
z += spacing;
count++;
}
}
function draw(t) {
drawSky();
drawStars(t);
drawShootingStars();
drawMountains();
drawSun(t);
drawGround();
drawSunReflection();
drawGrid(t);
}
function loop(now) {
const dt = (now - lastTime) / 16.67; // normalized to 60fps
lastTime = now;
ctx.setTransform(1, 0, 0, 1, 0, 0);
ctx.clearRect(0, 0, w(), h());
draw(now / 1000);
requestAnimationFrame(loop);
}
requestAnimationFrame(loop);
})();
</script>
</body>
</html>
```
Wait, I have a bug. I called resize() and applied devicePixelRatio scaling, but then I'm using innerWidth/innerHeight in the drawing functions. Let me restructure this.
Let me simplify: just use canvas at viewport size with CSS, no DPR scaling (or do it properly).
Actually let me do DPR scaling properly:
```javascript
let DPR = window.devicePixelRatio || 1;
let W, H; // logical pixels
function resize() {
W = window.innerWidth;
H = window.innerHeight;
canvas.width = W * DPR;
canvas.height = H * DPR;
canvas.style.width = W + 'px';
canvas.style.height = H + 'px';
ctx.setTransform(DPR, 0, 0, DPR, 0, 0);
}
```
Then I can use W, H for logical coordinates. And in animation loop I should reset transform if needed. Actually since I only set transform once on resize, I should be fine.
But wait, when the canvas dimensions change, I need to reset transform. Let me handle that:
```javascript
function resize() {
DPR = window.devicePixelRatio || 1;
W = window.innerWidth;
H = window.innerHeight;
canvas.width = W * DPR;
canvas.height = H * DPR;
canvas.style.width = W + 'px';
canvas.style.height = H + 'px';
// Reset transform to identity first
ctx.setTransform(1, 0, 0, 1, 0, 0);
// Then apply DPR scaling
ctx.scale(DPR, DPR);
}
```
And in the loop, don't reset transform between frames.
Let me rewrite more carefully. I'll use a simpler approach: use devicePixelRatio only if it's reasonable, otherwise 1.
Actually for simplicity and to avoid edge cases, let me skip DPR scaling and just use CSS size as canvas size. The result is a bit less crisp on high-DPI displays but it's simpler. Actually wait, that would make it pixelated on retina. Let me do DPR properly.
Hmm, let me also think about the grid scrolling. I want a continuous, smooth motion. The math I wrote should work:
```
y = cy + (H - cy) * z / (z + K)
```
Where K is a constant. Larger K = more "depth" feeling (lines stay near horizon longer). Smaller K = lines move down quickly.
Let me check with K=12:
- z=0: y=cy (at horizon)
- z=12: y=cy + (H-cy)*0.5
- z=infinity: y=cy + (H-cy) = H
So lines at depth z=12 are halfway down. Good.
For animation:
- gridZ increases by speed per frame
- Current line is at depth = gridZ % spacing
- This means: a new line emerges at horizon when gridZ wraps, and existing lines move forward
Wait, but lines should appear to come FROM horizon and go TO viewer. So as gridZ increases, the "current offset" increases, meaning the line that's at depth=gridZ%spacing moves from small z to larger z, which moves its y position from horizon down to bottom. Good.
But when it wraps, a line "teleports" back to horizon. That's fine because it's right at the horizon (invisible).
Let me also consider: the grid should be over the reflection (so reflection is partially obscured by grid lines, like real reflection in water).
Order of drawing:
1. Sky
2. Stars
3. Mountains
4. Sun
5. Ground
6. Reflection (sun's mirror)
7. Grid (over reflection)
Hmm, or maybe grid should be UNDER reflection but ABOVE ground gradient. Let me think...
Actually in synthwave aesthetic, the reflection is the grid itself reflecting, kind of. Let me draw the reflection first, then the grid on top (which adds the horizontal lines over the reflection).
Let me also think about adding a "neon glow" effect. Using shadowBlur helps but it's slow. Let me use it sparingly.
One more thought: the mountains should be silhouetted in the sun's glow area, creating a dark cutout against the bright sun. Let me make sure they overlap.
Now let me also think about colors more carefully:
- Sun: yellow → orange → magenta → purple gradient
- Grid: neon pink/magenta (or cyan)
- Sky: purple to orange
- Stars: white/pale
Let me write the final HTML. I'll be careful with the code and make it look great.
Actually, I realize I should add some more visual polish:
- The sun should have a stronger glow
- Maybe add some pulsing effect
- The scanlines should be more crisp
- Maybe add a tiny palm tree or two on the sides
Actually let me keep it focused. The user asked for specific elements, so I'll deliver those well without too much extra.
Let me also think about animation timing:
- Grid scroll: ~1 unit of depth per second or so, for a steady feeling
- Star twinkle: slow random
- Maybe sun pulsing: very subtle
I'll set grid scroll speed to ~0.6 units per frame at 60fps. That gives a smooth continuous flow.
Let me write the final code now.
One thing: the mountains are at horizon level, but if they're "behind" the sun, they'd be silhouetted against it. In synthwave aesthetics, the mountains are usually silhouetted across the horizon line, sometimes in front of the sun. I'll put them in front of the sun for that classic look.
Actually wait, mountains on the horizon would be tiny silhouettes in real life (because they're far away). In synthwave, they're often drawn larger as decorative elements. I'll make them small silhouettes that the sun sits behind.
Let me also add: the very bottom of the sun touches the horizon line (it's "setting"). And the sun's reflection should appear right below.
OK, let me just write the damn code. Final version:
```html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Neon Sunset</title>
<style>
* { margin: 0; padding: 0; box-sizing: border-box; }
html, body {
width: 100%; height: 100%;
overflow: hidden;
background: #06002a;
color: #ff77d4;
font-family: 'Courier New', 'Consolas', monospace;
}
canvas {
display: block;
position: absolute;
top: 0; left: 0;
}
.scanlines {
position: fixed;
inset: 0;
pointer-events: none;
z-index: 5;
background: repeating-linear-gradient(
to bottom,
rgba(0, 0, 0, 0) 0px,
rgba(0, 0, 0, 0) 2px,
rgba(0, 0, 0, 0.18) 3px,
rgba(0, 0, 0, 0) 4px
);
mix-blend-mode: multiply;
}
.vignette {
position: fixed;
inset: 0;
pointer-events: none;
z-index: 6;
background:
radial-gradient(ellipse at center, transparent 35%, rgba(0,0,0,0.75) 100%);
}
.hud-top, .hud-bot {
position: fixed;
left: 0; right: 0;
text-align: center;
font-size: 10px;
letter-spacing: 0.45em;
z-index: 7;
text-shadow: 0 0 6px #ff2bd6, 0 0 12px rgba(255,43,214,0.6);
opacity: 0.75;
text-transform: uppercase;
}
.hud-top { top: 24px; }
.hud-bot { bottom: 24px; }
.hud-top span, .hud-bot span {
color: #67e3ff;
text-shadow: 0 0 6px #00d4ff;
}
</style>
</head>
<body>
<canvas id="c"></canvas>
<div class="scanlines"></div>
<div class="vignette"></div>
<div class="hud-top"><span>◢</span> S Y S T E M / N E O N S U N S E T <span>◣</span></div>
<div class="hud-bot">R E T R O W A V E / 1 9 8 5</div>
<script>
(() => {
'use strict';
const canvas = document.getElementById('c');
const ctx = canvas.getContext('2d', { alpha: false });
let DPR = Math.min(window.devicePixelRatio || 1, 2);
let W = 0, H = 0, horizon = 0;
function resize() {
W = window.innerWidth;
H = window.innerHeight;
DPR = Math.min(window.devicePixelRatio || 1, 2);
horizon = H * 0.6;
canvas.width = Math.floor(W * DPR);
canvas.height = Math.floor(H * DPR);
canvas.style.width = W + 'px';
canvas.style.height = H + 'px';
ctx.setTransform(DPR, 0, 0, DPR, 0, 0);
}
window.addEventListener('resize', resize);
resize();
// Generate stars
const stars = [];
const STAR_COUNT = 240;
for (let i = 0; i < STAR_COUNT; i++) {
const tints = ['#ffffff', '#ffffff', '#ffe7c2', '#cce8ff', '#ffd9f5'];
stars.push({
x: Math.random(),
y: Math.random() * 0.58,
r: Math.pow(Math.random(), 3) * 1.6 + 0.2,
a: Math.random() * 0.4 + 0.5,
tw: Math.random() * 0.05 + 0.015,
ph: Math.random() * Math.PI * 2,
c: tints[Math.floor(Math.random() * tints.length)]
});
}
// Distant mountain silhouettes
const mts = [];
for (let i = 0; i < 14; i++) {
mts.push({
x: Math.random(),
h: 0.015 + Math.random() * 0.035,
w: 0.04 + Math.random() * 0.08
});
}
mts.sort((a, b) => a.h - b.h); // smaller in front
// Shooting stars
const shootingStars = [];
function spawnShoot() {
shootingStars.push({
x: Math.random() * W * 0.8 + W * 0.1,
y: Math.random() * horizon * 0.4,
vx: -(4 + Math.random() * 5),
vy: 2 + Math.random() * 2.5,
life: 0,
max: 50 + Math.random() * 40
});
}
let nextShoot = 2000 + Math.random() * 3000;
// State
let gridZ = 0;
let lastT = performance.now();
let elapsed = 0;
function drawSky() {
const g = ctx.createLinearGradient(0, 0, 0, horizon);
g.addColorStop(0.00, '#04001f');
g.addColorStop(0.20, '#0e0540');
g.addColorStop(0.45, '#33086b');
g.addColorStop(0.70, '#791b6f');
g.addColorStop(0.90, '#d23a55');
g.addColorStop(1.00, '#ff8234');
ctx.fillStyle = g;
ctx.fillRect(0, 0, W, horizon);
}
function drawStars(t) {
for (const s of stars) {
const tw = Math.sin(t * s.tw + s.ph);
const a = Math.max(0.15, s.a + tw * 0.35);
ctx.globalAlpha = a;
ctx.fillStyle = s.c;
ctx.beginPath();
ctx.arc(s.x * W, s.y * horizon, s.r, 0, Math.PI * 2);
ctx.fill();
}
ctx.globalAlpha = 1;
}
function drawShooters(dt) {
for (let i = shootingStars.length - 1; i >= 0; i--) {
const s = shootingStars[i];
s.life += dt;
s.x += s.vx * dt;
s.y += s.vy * dt;
const prog = s.life / s.max;
if (prog >= 1 || s.x < -50 || s.y > horizon) {
shootingStars.splice(i, 1);
continue;
}
const a = (1 - prog) * 0.85;
const len = 80;
const tailX = s.x - s.vx * len / Math.hypot(s.vx, s.vy);
const tailY = s.y - s.vy * len / Math.hypot(s.vx, s.vy);
const g = ctx.createLinearGradient(s.x, s.y, tailX, tailY);
g.addColorStop(0, `rgba(255,255,255,${a})`);
g.addColorStop(0.5, `rgba(255,200,255,${a*0.4})`);
g.addColorStop(1, 'rgba(255,255,255,0)');
ctx.strokeStyle = g;
ctx.lineWidth = 1.4;
ctx.beginPath();
ctx.moveTo(s.x, s.y);
ctx.lineTo(tailX, tailY);
ctx.stroke();
}
}
function drawMountains() {
// Distant range
ctx.fillStyle = '#1a053a';
ctx.globalAlpha = 0.85;
for (const m of mts) {
const baseY = horizon;
const peakX = (m.x) * W;
const peakY = baseY - m.h * H;
const w2 = m.w * W;
ctx.beginPath();
ctx.moveTo(peakX - w2, baseY);
ctx.lineTo(peakX, peakY);
ctx.lineTo(peakX + w2 * 0.7, baseY);
ctx.closePath();
ctx.fill();
}
ctx.globalAlpha = 1;
}
function drawSun(t) {
const cx = W / 2;
const cy = horizon;
const baseR = Math.min(W, H) * 0.22;
const pulse = 1 + Math.sin(t * 0.8) * 0.012;
const r = baseR * pulse;
// Far glow
const farGlow = ctx.createRadialGradient(cx, cy, r * 0.5, cx, cy, r * 3.2);
farGlow.addColorStop(0, 'rgba(255, 90, 180, 0.35)');
farGlow.addColorStop(0.4, 'rgba(255, 60, 150, 0.12)');
farGlow.addColorStop(1, 'rgba(255, 60, 150, 0)');
ctx.fillStyle = farGlow;
ctx.fillRect(cx - r * 3.5, cy - r * 3.5, r * 7, r * 7);
// Inner glow
const nearGlow = ctx.createRadialGradient(cx, cy - r * 0.2, r * 0.3, cx, cy, r);
nearGlow.addColorStop(0, 'rgba(255, 240, 180, 0.6)');
nearGlow.addColorStop(1, 'rgba(255, 80, 150, 0)');
ctx.fillStyle = nearGlow;
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.fill();
// Sun body gradient
const g = ctx.createLinearGradient(cx, cy - r, cx, cy + r);
g.addColorStop(0.00, '#fff8d0');
g.addColorStop(0.18, '#ffe070');
g.addColorStop(0.42, '#ff9c3a');
g.addColorStop(0.68, '#ff3a7e');
g.addColorStop(1.00, '#7a1868');
ctx.fillStyle = g;
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.fill();
// Scanlines (lower portion only)
ctx.save();
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.clip();
const scanH = 3;
const scanGap = 5;
const startY = cy - r * 0.05;
const endY = cy + r;
const totalH = endY - startY;
const numLines = Math.floor(totalH / (scanH + scanGap));
// Variable spacing: tighter near top, wider near bottom for realism
for (let i = 0; i < numLines; i++) {
const t01 = i / Math.max(1, numLines - 1);
const y = startY + Math.pow(t01, 0.85) * totalH;
const thickness = scanH * (1 + t01 * 0.6);
const alpha = 0.45 + t01 * 0.3;
ctx.fillStyle = `rgba(8, 0, 22, ${alpha})`;
ctx.fillRect(cx - r, y, r * 2, thickness);
}
ctx.restore();
// Bright rim
ctx.strokeStyle = 'rgba(255, 240, 200, 0.5)';
ctx.lineWidth = 1.5;
ctx.beginPath();
ctx.arc(cx, cy, r - 0.5, 0, Math.PI * 2);
ctx.stroke();
}
function drawGround() {
const g = ctx.createLinearGradient(0, horizon, 0, H);
g.addColorStop(0, '#1a042e');
g.addColorStop(0.4, '#0a0114');
g.addColorStop(1, '#02000a');
ctx.fillStyle = g;
ctx.fillRect(0, horizon, W, H - horizon);
}
function drawReflection() {
const cx = W / 2;
const cy = horizon;
const r = Math.min(W, H) * 0.22;
const refH = H - horizon;
// Mirror gradient: same colors but inverted vertically, fading down
// The reflection uses the same palette as the sun
ctx.save();
ctx.beginPath();
ctx.rect(cx - r * 1.6, cy, r * 3.2, refH);
ctx.clip();
// Mirrored gradient: bright (sun's bottom) at top, fading down
// Sun's top is light yellow, bottom is purple. The reflection's TOP (just below horizon) shows the sun's BOTTOM (purple/pink).
// As we go down, reflection fades through orange to yellow (sun's top colors) and out.
// Wait, that's confusing. Let me think again.
//
// Actually the reflection is a flipped version of the sun. So if sun goes light→dark top to bottom,
// reflection goes light→dark bottom to top. The reflection just below horizon shows what was just above horizon (sun's bottom).
const g = ctx.createLinearGradient(cx, cy, cx, cy + refH);
g.addColorStop(0.00, '#7a1868');
g.addColorStop(0.15, '#ff3a7e');
g.addColorStop(0.35, '#ff9c3a');
g.addColorStop(0.55, '#ffe070');
g.addColorStop(0.80, 'rgba(255, 240, 180, 0.4)');
g.addColorStop(1.00, 'rgba(255, 240, 180, 0)');
ctx.fillStyle = g;
ctx.fillRect(cx - r * 1.6, cy, r * 3.2, refH);
ctx.restore();
// Horizontal shimmer lines (water-like effect)
ctx.save();
ctx.beginPath();
ctx.rect(cx - r * 1.6, cy, r * 3.2, refH);
ctx.clip();
const time = elapsed;
ctx.strokeStyle = 'rgba(255, 220, 180, 0.15)';
ctx.lineWidth = 1;
const shimmerCount = 22;
for (let i = 0; i < shimmerCount; i++) {
const tt = i / shimmerCount;
const y = cy + tt * refH * 0.95;
const offset = Math.sin(time * 1.5 + i * 0.7) * 4;
const widthFactor = 1 - tt * 0.5;
const xStart = cx - r * 1.6 * widthFactor + offset * 0.3;
const xEnd = cx + r * 1.6 * widthFactor + offset * 0.3;
ctx.beginPath();
ctx.moveTo(xStart, y);
ctx.lineTo(xEnd, y);
ctx.stroke();
}
ctx.restore();
}
function drawGrid() {
const cx = W / 2;
const cy = horizon;
const hh = H - cy;
// Vertical converging lines
ctx.shadowColor = 'rgba(255, 50, 200, 0.7)';
ctx.shadowBlur = 8;
ctx.strokeStyle = 'rgba(255, 70, 210, 0.95)';
ctx.lineWidth = 1.2;
const numV = 22;
const spread = W * 1.1;
for (let i = -numV; i <= numV; i++) {
if (i === 0) continue;
const xAtBottom = cx + i * (W / 14);
ctx.beginPath();
ctx.moveTo(cx, cy);
ctx.lineTo(xAtBottom, H);
ctx.stroke();
}
// Horizontal lines (animated)
ctx.shadowBlur = 0;
const K = 10;
const spacing = 1;
gridZ += 0.022;
let z = gridZ % spacing;
let i = 0;
while (i < 50) {
const denom = z + K;
const yPos = cy + hh * z / denom;
if (yPos > H) break;
const depth = Math.min(1, z / 6);
const alpha = 0.25 + depth * 0.75;
ctx.strokeStyle = `rgba(255, 80, 220, ${alpha})`;
ctx.shadowColor = `rgba(255, 50, 200, ${alpha * 0.8})`;
ctx.shadowBlur = 4 + depth * 8;
ctx.lineWidth = 0.7 + depth * 0.9;
ctx.beginPath();
ctx.moveTo(0, yPos);
ctx.lineTo(W, yPos);
ctx.stroke();
z += spacing;
i++;
}
}
function render(t) {
ctx.fillStyle = '#04001f';
ctx.fillRect(0, 0, W, H);
drawSky();
drawStars(t);
drawShooters(1);
drawMountains();
drawSun(t);
drawGround();
drawReflection();
drawGrid();
}
function loop(now) {
const dt = Math.min(2, (now - lastT) / 16.67);
lastT = now;
elapsed += dt / 60;
render(elapsed);
nextShoot -= (now - lastT + dt * 16.67); // hmm this is wrong
// Let me fix the shooting star timing
// ...
requestAnimationFrame(loop);
}
// Simpler approach: use elapsed time for spawning
// ...
})();
</script>
</body>
</html>
```
Hmm I have a bug in the shooting star timing. Let me fix that with a different approach using elapsed time:
```javascript
let nextShoot = 2 + Math.random() * 4;
let elapsedTotal = 0;
function loop(now) {
const dt = Math.min(2, (now - lastT) / 16.67);
lastT = now;
elapsedTotal += dt / 60;
elapsed += dt / 60;
nextShoot -= dt / 60;
if (nextShoot <= 0) {
spawnShoot();
nextShoot = 2 + Math.random() * 4;
}
drawShooters(dt);
// ... rest
requestAnimationFrame(loop);
}
```
Let me clean this up and write the final version. I'll write it all into the file now.
Actually, let me also reconsider some aspects:
1. The reflection - I want it to be a "reflected horizon" - I think the user means the horizon line is reflected (mirrored), so we see the sun's mirror image below the horizon. My approach is correct.
2. The grid scrolling - I'm doing it well with the z parameter and the perspective formula.
3. The stars - good with twinkle.
4. Sun scanlines - good with darker bands on the lower half.
5. The glow on the sun - good with radial gradients.
Let me also add: a chrome/text reflection at the very bottom, just for synthwave feel? No, focus on the core.
Let me also add: small "data" text or coordinates that update over time for that retro terminal feel. Or skip it.
I'll add subtle "data readouts" in the HUD. Actually I'll keep it minimal.
Let me also reconsider the grid line intensity. I want the lines near the horizon to be very faint (almost invisible) and the ones near the viewer to be bright. My formula does this correctly (alpha = 0.25 + depth * 0.75).
For vertical lines, they should also fade slightly with depth but in a different way. Actually they're static, so let me make them all bright but vary slightly.
Wait, the vertical lines converge at the vanishing point. So at the horizon they should all converge. As they go toward the viewer they spread out. Their brightness could be uniform or also fade with depth.
Hmm, for performance, let me not over-complicate. Just keep vertical lines bright and uniform.
One issue: shadowBlur is expensive. Using it on every horizontal line in the grid could be slow. Let me use it more sparingly, or use additive blending.
Let me use additive blending for the grid instead:
```javascript
ctx.globalCompositeOperation = 'lighter';
// ... draw grid with lighter colors
```
This will make the grid feel more neon and glowy.
Actually for synthwave, the classic look is bright neon lines. Additive blending (lighter) helps achieve that. Let me use it.
For the sun's reflection, I might want to use 'lighter' too for the bright parts.
OK let me finalize. Here's my plan:
- Sky: simple gradient
- Stars: simple dots with twinkle
- Sun: layered gradients + scanlines on lower half + glow
- Ground: gradient
- Reflection: mirrored gradient with shimmer
- Grid: perspective lines, animated, with neon glow
I'll use additive blending for the grid for that bright glowy effect.
Let me also make sure the page works on a fresh load with no console errors.
Final code time. Let me write the whole file:
```html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>SYNTHWAVE // SUNSET</title>
<style>
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html, body {
width: 100%; height: 100%;
overflow: hidden;
background: #04001a;
color: #ff7fda;
font-family: 'Courier New', 'Consolas', monospace;
}
body { position: relative; }
canvas#c {
display: block;
position: absolute;
inset: 0;
width: 100%;
height: 100%;
}
.overlay {
position: absolute;
inset: 0;
pointer-events: none;
}
.scanlines {
z-index: 5;
background-image: repeating-linear-gradient(
to bottom,
rgba(0,0,0,0) 0,
rgba(0,0,0,0) 2px,
rgba(0,0,0,0.22) 3px,
rgba(0,0,0,0) 4px
);
mix-blend-mode: multiply;
opacity: 0.85;
}
.vignette {
z-index: 6;
background:
radial-gradient(ellipse at center, transparent 45%, rgba(0,0,0,0.85) 100%);
}
.hud {
z-index: 7;
color: #ff7fda;
text-shadow: 0 0 4px #ff2bd6, 0 0 10px rgba(255,43,214,0.7);
letter-spacing: 0.4em;
font-size: 10px;
text-transform: uppercase;
opacity: 0.85;
}
.hud-top {
position: absolute;
top: 22px; left: 0; right: 0;
text-align: center;
}
.hud-bot {
position: absolute;
bottom: 22px; left: 0; right: 0;
text-align: center;
}
.hud .accent {
color: #67e3ff;
text-shadow: 0 0 4px #00d4ff, 0 0 10px rgba(0,212,255,0.6);
}
.corner {
position: absolute;
width: 60px; height: 60px;
border: 1px solid rgba(255,43,214,0.4);
z-index: 7;
}
.corner.tl { top: 14px; left: 14px; border-right: 0; border-bottom: 0; }
.corner.tr { top: 14px; right: 14px; border-left: 0; border-bottom: 0; }
.corner.bl { bottom: 14px; left: 14px; border-right: 0; border-top: 0; }
.corner.br { bottom: 14px; right: 14px; border-left: 0; border-top: 0; }
</style>
</head>
<body>
<canvas id="c"></canvas>
<div class="overlay scanlines"></div>
<div class="overlay vignette"></div>
<div class="corner tl"></div>
<div class="corner tr"></div>
<div class="corner bl"></div>
<div class="corner br"></div>
<div class="hud hud-top">◆ <span class="accent">N E O N</span> S U N S E T S Y S T E M ◆</div>
<div class="hud hud-bot">R E T R O W A V E / <span class="accent">1 9 8 5</span></div>
<script>
(() => {
'use strict';
const canvas = document.getElementById('c');
const ctx = canvas.getContext('2d', { alpha: false });
let DPR = 1, W = 0, H = 0, horizon = 0;
let groundH = 0;
function resize() {
DPR = Math.min(window.devicePixelRatio || 1, 2);
W = window.innerWidth;
H = window.innerHeight;
horizon = H * 0.6;
groundH = H - horizon;
canvas.width = Math.floor(W * DPR);
canvas.height = Math.floor(H * DPR);
canvas.style.width = W + 'px';
canvas.style.height = H + 'px';
ctx.setTransform(DPR, 0, 0, DPR, 0, 0);
}
window.addEventListener('resize', resize, { passive: true });
resize();
// ----- Stars -----
const stars = [];
const STAR_COUNT = 260;
const starColors = ['#ffffff', '#ffffff', '#ffe7c2', '#cce8ff', '#ffd9f5'];
for (let i = 0; i < STAR_COUNT; i++) {
stars.push({
x: Math.random(),
y: Math.random() * 0.58,
r: Math.pow(Math.random(), 2.5) * 1.5 + 0.2,
a: Math.random() * 0.4 + 0.5,
tw: 0.015 + Math.random() * 0.04,
ph: Math.random() * Math.PI * 2,
c: starColors[Math.floor(Math.random() * starColors.length)]
});
}
// ----- Mountains -----
const mts = [];
for (let i = 0; i < 18; i++) {
mts.push({
x: -0.05 + Math.random() * 1.1,
h: 0.012 + Math.random() * 0.04,
w: 0.035 + Math.random() * 0.07
});
}
mts.sort((a, b) => b.h - a.h);
// ----- Shooting stars -----
const shooters = [];
function spawnShooter() {
shooters.push({
x: W * (0.2 + Math.random() * 0.7),
y: Math.random() * horizon * 0.35,
vx: -(5 + Math.random() * 6),
vy: 2 + Math.random() * 2.5,
life: 0,
max: 60 + Math.random() * 40
});
}
let shootTimer = 2 + Math.random() * 3;
// ----- Animation state -----
let gridZ = 0;
let lastT = performance.now();
let tElapsed = 0;
// ===== Drawing functions =====
function drawSky() {
const g = ctx.createLinearGradient(0, 0, 0, horizon);
g.addColorStop(0.00, '#02001a');
g.addColorStop(0.18, '#0c0438');
g.addColorStop(0.40, '#2c0a64');
g.addColorStop(0.65, '#691e6f');
g.addColorStop(0.85, '#c93a55');
g.addColorStop(1.00, '#ff8234');
ctx.fillStyle = g;
ctx.fillRect(0, 0, W, horizon);
}
function drawStars(t) {
for (const s of stars) {
const tw = Math.sin(t * s.tw + s.ph);
const a = Math.max(0.15, s.a + tw * 0.35);
ctx.globalAlpha = a;
ctx.fillStyle = s.c;
ctx.beginPath();
ctx.arc(s.x * W, s.y * horizon, s.r, 0, Math.PI * 2);
ctx.fill();
}
ctx.globalAlpha = 1;
}
function drawShooters(dt) {
for (let i = shooters.length - 1; i >= 0; i--) {
const s = shooters[i];
s.life += dt;
s.x += s.vx * dt;
s.y += s.vy * dt;
const prog = s.life / s.max;
if (prog >= 1 || s.x < -60 || s.y > horizon) {
shooters.splice(i, 1);
continue;
}
const a = (1 - prog) * 0.9;
const speed = Math.hypot(s.vx, s.vy);
const tailX = s.x - s.vx * 25 / speed;
const tailY = s.y - s.vy * 25 / speed;
const g = ctx.createLinearGradient(s.x, s.y, tailX, tailY);
g.addColorStop(0, `rgba(255,255,255,${a})`);
g.addColorStop(0.6, `rgba(255,200,255,${a*0.5})`);
g.addColorStop(1, 'rgba(255,255,255,0)');
ctx.strokeStyle = g;
ctx.lineWidth = 1.4;
ctx.beginPath();
ctx.moveTo(s.x, s.y);
ctx.lineTo(tailX, tailY);
ctx.stroke();
}
}
function drawMountains() {
ctx.fillStyle = '#16052e';
ctx.globalAlpha = 0.88;
for (const m of mts) {
const baseY = horizon;
const peakX = m.x * W;
const peakY = baseY - m.h * H;
const w2 = m.w * W;
ctx.beginPath();
ctx.moveTo(peakX - w2, baseY);
ctx.lineTo(peakX, peakY);
ctx.lineTo(peakX + w2 * 0.7, baseY);
ctx.closePath();
ctx.fill();
}
ctx.globalAlpha = 1;
}
function drawSun(t) {
const cx = W / 2;
const cy = horizon;
const baseR = Math.min(W, H) * 0.22;
const pulse = 1 + Math.sin(t * 0.7) * 0.012;
const r = baseR * pulse;
// Wide outer glow
const big = ctx.createRadialGradient(cx, cy, r * 0.4, cx, cy, r * 3.5);
big.addColorStop(0, 'rgba(255, 90, 180, 0.32)');
big.addColorStop(0.35, 'rgba(255, 60, 140, 0.10)');
big.addColorStop(1, 'rgba(255, 60, 140, 0)');
ctx.fillStyle = big;
ctx.fillRect(cx - r * 3.6, cy - r * 3.6, r * 7.2, r * 7.2);
// Body gradient
const g = ctx.createLinearGradient(cx, cy - r, cx, cy + r);
g.addColorStop(0.00, '#fff8d0');
g.addColorStop(0.20, '#ffe070');
g.addColorStop(0.45, '#ff9c3a');
g.addColorStop(0.72, '#ff3a7e');
g.addColorStop(1.00, '#7a1868');
ctx.fillStyle = g;
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.fill();
// Scanlines on lower portion
ctx.save();
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.clip();
const startY = cy - r * 0.08;
const endY = cy + r;
const totalH = endY - startY;
const numLines = Math.floor(totalH / 7);
for (let i = 0; i < numLines; i++) {
const tt = i / numLines;
const y = startY + Math.pow(tt, 0.82) * totalH;
const thick = 2.2 + tt * 1.8;
const alpha = 0.5 + tt * 0.35;
ctx.fillStyle = `rgba(8, 0, 22, ${alpha})`;
ctx.fillRect(cx - r, y, r * 2, thick);
}
ctx.restore();
// Soft top highlight
const hi = ctx.createRadialGradient(cx, cy - r * 0.55, r * 0.15, cx, cy - r * 0.2, r * 0.7);
hi.addColorStop(0, 'rgba(255, 255, 230, 0.45)');
hi.addColorStop(1, 'rgba(255, 255, 230, 0)');
ctx.save();
ctx.beginPath();
ctx.arc(cx, cy, r, 0, Math.PI * 2);
ctx.clip();
ctx.fillStyle = hi;
ctx.fillRect(cx - r, cy - r, r * 2, r * 2);
ctx.restore();
}
function drawGround() {
const g = ctx.createLinearGradient(0, horizon, 0, H);
g.addColorStop(0, '#1c0536');
g.addColorStop(0.45, '#080112');
g.addColorStop(1, '#010005');
ctx.fillStyle = g;
ctx.fillRect(0, horizon, W, groundH);
}
function drawReflection(t) {
const cx = W / 2;
const cy = horizon;
const r = Math.min(W, H) * 0.22;
ctx.save();
ctx.beginPath();
ctx.rect(0, cy, W, groundH);
ctx.clip();
// Mirrored gradient column, wider than sun, fading down
const colW = r * 3.4;
const g = ctx.createLinearGradient(cx, cy, cx, H);
g.addColorStop(0.00, '#7a1868');
g.addColorStop(0.10, '#ff3a7e');
g.addColorStop(0.25, '#ff6a4a');
g.addColorStop(0.45, '#ff9c3a');
g.addColorStop(0.60, '#ffd06a');
g.addColorStop(0.80, 'rgba(255, 220, 160, 0.25)');
g.addColorStop(1.00, 'rgba(255, 220, 160, 0)');
ctx.fillStyle = g;
ctx.fillRect(cx - colW/2, cy, colW, groundH);
// Horizontal taper: stronger in middle
ctx.globalCompositeOperation = 'destination-in';
const taper = ctx.createLinearGradient(cx - colW/2, 0, cx + colW/2, 0);
taper.addColorStop(0, 'rgba(0,0,0,0)');
taper.addColorStop(0.25, 'rgba(0,0,0,0.3)');
taper.addColorStop(0.5, 'rgba(0,0,0,1)');
taper.addColorStop(0.75, 'rgba(0,0,0,0.3)');
taper.addColorStop(1, 'rgba(0,0,0,0)');
ctx.fillStyle = taper;
ctx.fillRect(cx - colW/2, cy, colW, groundH);
ctx.globalCompositeOperation = 'source-over';
ctx.restore();
// Shimmer lines on top of reflection
ctx.save();
ctx.beginPath();
ctx.rect(0, cy, W, groundH);
ctx.clip();
ctx.strokeStyle = 'rgba(255, 220, 180, 0.18)';
ctx.lineWidth = 1;
const shimmerCount = 30;
for (let i = 0; i < shimmerCount; i++) {
const tt = i / shimmerCount;
const y = cy + tt * groundH * 0.9;
const fade = 1 - tt;
const offset = Math.sin(t * 1.8 + i * 0.9) * 6;
const wf = 0.4 + fade * 0.5;
const xStart = cx - r * 1.6 * wf + offset * 0.4;
const xEnd = cx + r * 1.6 * wf + offset * 0.4;
ctx.globalAlpha = 0.15 + fade * 0.25;
ctx.beginPath();
ctx.moveTo(xStart, y);
ctx.lineTo(xEnd, y);
ctx.stroke();
}
ctx.globalAlpha = 1;
ctx.restore();
}
function drawGrid() {
const cx = W / 2;
const cy = horizon;
const gh = groundH;
ctx.globalCompositeOperation = 'lighter';
// Vertical converging lines
ctx.strokeStyle = 'rgba(255, 70, 210, 0.85)';
ctx.lineWidth = 1.2;
ctx.shadowColor = 'rgba(255, 40, 200, 0.7)';
ctx.shadowBlur = 6;
const numV = 22;
for (let i = -numV; i <= numV; i++) {
if (i === 0) continue;
const xAtBottom = cx + i * (W / 14);
ctx.beginPath();
ctx.moveTo(cx, cy);
ctx.lineTo(xAtBottom, H);
ctx.stroke();
}
// Animated horizontal lines
const K = 10;
gridZ += 0.022;
let z = gridZ % 1;
let n = 0;
while (n < 60) {
const denom = z + K;
const yPos = cy + gh * z / denom;
if (yPos > H) break;
const depth = Math.min(1, z / 7);
const alpha = 0.2 + depth * 0.8;
ctx.strokeStyle = `rgba(255, 80, 220, ${alpha})`;
ctx.shadowColor = `rgba(255, 50, 200, ${alpha * 0.6})`;
ctx.shadowBlur = 3 + depth * 9;
ctx.lineWidth = 0.7 + depth * 1.0;
ctx.beginPath();
ctx.moveTo(0, yPos);
ctx.lineTo(W, yPos);
ctx.stroke();
z += 1;
n++;
}
ctx.shadowBlur = 0;
ctx.globalCompositeOperation = 'source-over';
}
// ===== Main loop =====
function frame(now) {
const dt = Math.min(3, (now - lastT) / 16.67);
lastT = now;
tElapsed += dt / 60;
// Shooting star timing
shootTimer -= dt / 60;
if (shootTimer <= 0) {
spawnShooter();
shootTimer = 2.5 + Math.random() * 4;
}
// Clear with base color (helps if any alpha leaks)
ctx.fillStyle = '#04001a';
ctx.fillRect(0, 0, W, H);
drawSky();
drawStars(tElapsed);
drawShooters(dt);
drawMountains();
drawSun(tElapsed);
drawGround();
drawReflection(tElapsed);
drawGrid();
requestAnimationFrame(frame);
}
requestAnimationFrame(frame);
})();
</script>
</body>
</html>
```
Wait, I should double-check a few things:
1. `ctx.globalCompositeOperation = 'lighter'` for the grid - this makes overlapping lines brighter. Good for neon glow.
2. The reflection uses `destination-in` to mask with horizontal taper. This should work.
3. The horizontal lines animation: when gridZ increments, the line at `z = gridZ % 1` starts at the horizon and moves outward. Good.
4. DPR scaling: I set transform on resize, then on each frame I clear with `ctx.fillRect`. The transform should remain set. Let me make sure I don't accidentally reset it.
5. The scanlines inside the sun: I clip to the circle, then fill rectangles. The rectangles are clipped to the circle, so only the part inside the circle gets drawn. Good.
Let me trace through one issue: when I set `ctx.fillStyle = 'rgba(8, 0, 22, 0.85)'` for scanlines, I want them to be dark/transparent so the dark band shows. The sun's color shows around them. Good.
Another consideration: the globalAlpha settings need to be reset. Let me make sure all paths that change globalAlpha reset it.
I think the code is good. Let me write it to the file now.
Oh wait, one thing: when I use `globalCompositeOperation = 'lighter'` for the grid, this adds to existing pixels. But the reflection is drawn before the grid. So the grid will lighten/add to the reflection in its area. That's the desired effect — grid lines glowing on top of reflection. Good.
But wait, the reflection was drawn with `globalCompositeOperation = 'destination-in'`, which I reset after. Then when I draw the grid with 'lighter', it'll blend additively with whatever's below (the reflection and ground gradient). Good.
Let me also check: the shimmer lines in reflection are drawn AFTER setting globalCompositeOperation back to source-over, but I set globalAlpha within. That should work since globalAlpha is independent of composite operation.
Hmm wait, I draw shimmer after restore, so composite is source-over by default. Good.
Let me also think about: should the grid lines BE the reflection? Or on top of the reflection?
In synthwave aesthetic, the grid is often seen as the ground stretching out, with the sun's reflection appearing on the ground (or as part of the grid). The grid lines should be visible OVER the reflection, because they're the structure of the ground, and the reflection is the color/shading on the ground.
So: draw reflection first (ground color + sun's mirror), then grid lines on top. That's what I'm doing. Good.
Let me also consider: the horizontal grid lines pass through the reflection area, and as they get closer to the viewer, they should be more saturated/bright. My alpha formula gives 0.2 to 1.0. That's OK but maybe the dim ones (far) should be even dimmer. Let me use `0.15 + depth * 0.85`. Or maybe even add a hint of pink.
Actually let me look at this more carefully. When z is small (near horizon), depth is small, alpha is low. As z increases (toward viewer), alpha increases. At z=7, depth=1, alpha=1.0. Good progression.
One more thing: the vertical grid lines should also fade with depth. In my current code they're uniform. Let me make them slightly more interesting. Actually no, since they're converging to a point, the perspective itself provides the visual depth. Keep them uniform.
OK let me write the file.
Actually one more concern: performance. With shadowBlur on every horizontal grid line, plus 260 stars, plus all the other stuff, performance might suffer on slower devices. Let me reduce shadowBlur usage:
- Stars: no shadow
- Sun glow: no shadow (just radial gradients)
- Sun rim: no shadow
- Grid horizontal lines: shadowBlur = small
- Grid vertical lines: shadowBlur = small
- Reflections: no shadow
This should be fine.
Also: the alpha-based fade on grid lines means we're creating new strings every frame. That's slow. Let me precompute or just accept it. Pre-computing color strings is also fine.
Actually creating strings is fine, modern engines optimize this. Let me not worry.
Alright, let me finalize and write the file. I'll also do a sanity check by running the code mentally:
1. Page loads, script runs.
2. Canvas is sized, DPR applied.
3. Stars, mountains, shooters arrays populated.
4. requestAnimationFrame starts the loop.
5. Each frame:
- Clear with base color
- Draw sky gradient (top half)
- Draw stars (with twinkle)
- Draw any shooting stars
- Draw mountains
- Draw sun with scanlines (top half, near horizon)
- Draw ground gradient (bottom half)
- Draw reflection of sun on ground (with shimmer)
- Draw grid (vertical + horizontal with animation)
6. CRT overlay and vignette are CSS layers on top of canvas.
The result should look like a synthwave sunset. Let me make sure the synthwave aesthetic is strong:
- ✓ Pink/magenta neon grid
- ✓ Sun with scanlines
- ✓ Gradient sky
- ✓ Stars
- ✓ Reflected sun
- ✓ Mountains for depth
- ✓ CSS scanlines overlay for retro CRT
- ✓ HUD text in corners (decorative)
- ✓ Shooting stars for animation interest
- ✓ Vignette for focus
Good. Let me write the file.
One last thing: I should make sure the canvas fills the viewport and doesn't have scrollbars. My CSS sets `overflow: hidden` on body and `position: absolute` on canvas with `inset: 0`. Good.
Final file time!
Wait, let me also think about whether to add some chrome metallic text on the horizon (a classic synthwave element). The user didn't ask for it, so I'll skip. The HUD with corner brackets and top/bottom text is enough decoration.
Actually, let me also add a small "loading" or transition effect... no, the user wants it animated and playing immediately. Skip.
Let me also verify the colors look good:
- Sky top: deep dark purple (#02001a)
- Sky bottom (horizon): orange-pink (#ff8234)
- Sun top: light yellow (#fff8d0)
- Sun middle: orange (#ff9c3a)
- Sun bottom: dark magenta (#7a1868)
- Grid: magenta/pink (#ff50d8 with glow)
- Mountains: dark purple (#16052e)
- Ground: dark purple to black
- Reflection: same colors as sun (mirrored)
These are classic synthwave colors. Good.
Final code coming up. Let me write it out cleanly.
Hmm, actually I want to also add a "neon glow" effect on the grid where lines near the horizon fade in more gradually. Right now my depth calculation gives:
- z=0: depth=0, alpha=0.2
- z=7: depth=1, alpha=1.0
So lines near horizon (small z) have alpha 0.2 (visible but dim), and lines near viewer have alpha 1.0 (fully bright). Good.
OK finalizing now.
Let me also think about one bug: I have `ctx.fillStyle = '#04001a'; ctx.fillRect(0, 0, W, H);` at the start of each frame to clear. But this overrides any existing content. Combined with `{ alpha: false }` on the canvas context, this should give me a clean canvas each frame. Good.
One issue: `ctx.getContext('2d', { alpha: false })` makes the canvas opaque, which is what I want. The clear color is then the canvas background. Good.
Alright, writing the file.
Actually one more thing - I realize I should double check the perspective math. Let me verify with a few examples:
- W=1920, H=1080, horizon = 648, groundH = 432
- For z=10, K=10: yPos = 648 + 432 * 10 / 20 = 648 + 216 = 864
- That's halfway down the ground area. Good.
- For z=0.5: yPos = 648 + 432 * 0.5 / 10.5 = 648 + 20.6 = 668.6
- Just below horizon, very close. Good.
- For z=20: yPos = 648 + 432 * 20 / 30 = 648 + 288 = 936
- 2/3 down. Good.
- For z=50: yPos = 648 + 432 * 50 / 60 = 648 + 360 = 1008
- Near bottom. Good.
Math checks out.
Animation: gridZ increases by 0.022 per frame at 60fps. After ~45 frames, gridZ = 1.0, so z (which is gridZ % 1) wraps. So a new line emerges at horizon about every 0.75 seconds. The horizontal lines move smoothly from horizon toward viewer.
That feels about right for a synthwave grid scroll. Maybe a touch faster would be better. Let me use 0.03 for slightly faster motion.
Actually, let me reconsider. The grid scroll speed should feel "infinite" — like the viewer is moving forward through space. Slower = more contemplative, faster = more energetic. 0.022 is fine. Maybe I'll use 0.025 as a middle ground.
OK, writing the file now. Truly final version.
Hmm, I realize there's a potential issue with how I'm sizing things. The CSS sets the canvas to 100% of body (which is 100vw x 100vh). The canvas's internal pixel dimensions are W*DPR x H*DPR. The transform maps logical to physical pixels.
When I draw with logical coordinates (using W, H which are innerWidth, innerHeight), it should map correctly to physical pixels via the DPR scaling. Good.
For star positions: I store `s.x` as a fraction (0-1) and multiply by W at draw time. Good.
For mountains: `m.x * W` gives pixel position. Good.
OK, writing now!
Oh wait, I have a subtle issue. When I call resize, I reset the canvas dimensions (canvas.width/height), which resets the context state including transforms. Then I call setTransform. Good.
But what about during the resize event? If the resize fires mid-frame... actually, resize events are usually batched and not super frequent. Let me not worry.
Final code coming up. Here it is:
Oh, also: I should consider what happens on very small screens. The sun radius is Math.min(W, H) * 0.22. On a phone (e.g., 375x667), min is 375, so r = 82.5px. That's reasonable.
On a wide screen (e.g., 2560x1440), min is 1440, so r = 316.8px. That's huge but OK.
On a portrait phone (375x812), min is 375, r = 82.5. OK.
Looks fine.
One more thing: let me also test the reflection logic. The reflection is drawn with `globalCompositeOperation = 'destination-in'` to apply a horizontal taper mask. This requires that the canvas was already drawn to (with the source pixels). Let me trace:
1. Save state, clip to ground rect.
2. Draw vertical gradient rectangle (full color from horizon to bottom, full width colW).
3. Apply horizontal taper via `destination-in` — this keeps only pixels where the taper has alpha > 0.
4. Reset composite to source-over.
5. Restore state.
The `destination-in` mode means: the new pixel keeps its alpha only where the destination (the new pixels being drawn, i.e., the taper gradient) has non-zero alpha. The destination is what we're drawing now (the taper), not what's already on canvas. Wait, let me check.
`destination-in`: "The new shape is drawn only where both the new shape and the destination canvas overlap. Everything else is made transparent."
So if I draw a horizontal gradient (the taper) with destination-in, the pixels that already exist on canvas (the reflection gradient) are kept only where the new shape (taper) has non-zero alpha. So the taper acts as a mask. Good, that's what I want.
Wait actually I think I had it backwards. Let me re-check:
From MDN: "destination-in: The new shape is drawn only where both the new shape and the destination canvas overlap. Everything else is made transparent."
So: "destination canvas" = existing canvas content (the vertical reflection gradient).
"new shape" = what I'm drawing (the horizontal taper).
Result: Only pixels where BOTH the existing content AND the new shape exist are kept. The new shape's color/alpha doesn't matter for visibility, only its alpha mask. Other pixels (where new shape doesn't exist) are made transparent.
So I draw the horizontal taper gradient over the existing reflection. The taper is RGBA where alpha varies from 0 to 1 horizontally. With destination-in, the existing reflection is kept only where the taper has non-zero alpha. This creates a horizontal taper mask.
OK my logic is correct. The taper gradient I defined has alpha 0 at edges, 1 in middle, which gives a smooth horizontal fade.
Alright, truly writing the file now.
Actually I realize one more thing: when using destination-in, the COLOR of the new shape doesn't matter for the result (only the alpha). So my gradient with `rgba(0,0,0,X)` works.
OK here we go:
I want to write the file. Let me first check the working directory.
Let me now write the full HTML file with all the careful considerations I've worked through.I'llcreate a synthwave sunset with all the requested elements. Let me first check the working directory and then build the file.
→ bash
{"command":"pwd && ls -la"}toolResult
/workspace total 4 drwxrwxrwx 2 node node 64 Jul 22 16:49 . drwxr-xr-x 1 root root 4096 Jul 22 16:49 ..
assistant
thinking
Empty workspace. Let me write the file now.Now
I'll write the complete synthwave sunset. I'll build it with Canvas 2D for crisp vector graphics, layering: gradient sky → twinkling stars → distant mountain silhouettes → the sun (gradient body + horizontal scanlines + outer glow) → ground gradient → the reflected sun (mirrored gradient with shimmering horizontal bands) → the neon perspective grid that scrolls toward the viewer with additive blending for that classic neon glow.
→ write
/workspace/index.html (13194 bytes)toolResult
Successfully wrote 13194 bytes to /workspace/index.html
assistant
thinking
File created. Let me verify it exists and has the right contents by checking the file size and a snippet.
Created the file. Let me verify it's intact and properly self-contained.
→ bash
{"command":"ls -la /workspace/index.html && echo \"---\" && head -5 /workspace/index.html && echo \"---\" && tail -5 /workspace/index.html &toolResult
-rw-r--r-- 1 node node 13198 Jul 22 16:55 /workspace/index.html --- <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> --- requestAnimationFrame(frame); })(); </script> </body> </html> --- External resource check: (none found - good)
assistant
thinking
File is self-contained, no external resources. Let me also quickly run a syntax check on the JS by extracting it and using node. Self
-contained with zero external resources. Let me do a quick syntax sanity check on the embedded JavaScript to make sure it parses cleanly.
→ bash
{"command":"node -e \"\nconst fs = require('fs');\nconst html = fs.readFileSync('index.html', 'utf8');\nconst m = html.match(/<script>([\\s\toolResult
JS parses OK (10549 chars) OK drawSky OK drawStars OK drawSun (with scanlines) OK drawReflection OK drawGrid OK starfield OK shooting stars OK grid scroll math
assistant
thinking
All sections present, JS parses cleanly. The file is complete and ready.
`index.html` is ready and self-contained (≈13 KB, no network requests). **What's in the scene** - **Gradient sky** — deep indigo at the top, transitioning through violet and rose into a hot orange band at the horizon - **Starfield** — 260 stars with per-star phase and speed for an organic twinkle, plus occasional shooting stars streaking diagonally - **Distant mountains** — soft purple silhouettes breaking the horizon for depth - **The sun** — a circular gradient (white‑yellow → orange → magenta → deep purple) with a wide radial halo, a soft top highlight, and horizontal **scanlines** that clip cleanly to the lower portion of the disc, getting thicker and denser toward the bottom - **Reflected horizon** — the sun mirrored onto the ground via a vertically‑inverted gradient column, tapered to the sides with a `destination‑in` mask, and overlaid with 34 shimmering horizontal bands that drift with `sin(t)` for a watery effect - **Infinite neon grid** — 22 magenta vertical lines converging on the vanishing point, plus perspective horizontal lines spaced by `y = horizon + gh · z/(z+K)` that scroll continuously toward the viewer (lines emerge from the horizon and accelerate as they approach, with alpha and shadow‑blur ramping from faint to fully neon) - **Retro finishing touches** — CRT scanline overlay, edge vignette, corner brackets, and small "RETROWAVE / 1985" HUD text, all in pure CSS Open `index.html` in any browser and the sunset plays immediately.
TAKE IT TO CODE
A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.
RUN
modelminimax-m3
vendorMiniMax
harnesspi-agent
generated2026-07-22
EVALUATION
★★★★★ 4/5 working
Static synthwave sunset scene with grid, sun, and starfield; no visible animation or reaction to input.
Vision grade · anthropic/claude-sonnet-5
MEASUREMENTS
Raw readings from the capture, not a verdict — the grade above is the only judgement. Percentages are how much of the screen changed; the measure under-reports sparse motion on a dark background.
idle motion3.6%
on click0.8%
on drag2.4%
on wheel3.4%
on enter + space1.6%
on arrow keys1.8%
on w/a/s/d0.7%
frame spread54.5 / 255
console errors0
js errors none
METRICS
runtime373.6s
tokens in31k
tokens out28k
cached81k
cost / run$0.0472