Replace hero with monochrome particle artwork

README.md

@@ -1,6 +1,6 @@
 # Aither
 
-![Aither — Living particle orbs for SwiftUI](Media/hero.jpg)
+![Aither — Living particle orbs for SwiftUI](Media/hero.png)
 
 Aither is a dependency-free package for expressive, continuously looping
 particle orbs. Its primary API is native SwiftUI, backed by an efficient

Scripts/render-hero.swift

@@ -0,0 +1,146 @@
+#!/usr/bin/env swift
+
+import AppKit
+
+struct Particle {
+    var x: CGFloat
+    var y: CGFloat
+    var z: CGFloat
+    var size: CGFloat
+    var opacity: CGFloat
+}
+
+private let canvasWidth = 3_200
+private let canvasHeight = 1_280
+private let outputURL = URL(fileURLWithPath: CommandLine.arguments.dropFirst().first ?? "Media/hero.png")
+
+guard let bitmap = NSBitmapImageRep(
+    bitmapDataPlanes: nil,
+    pixelsWide: canvasWidth,
+    pixelsHigh: canvasHeight,
+    bitsPerSample: 8,
+    samplesPerPixel: 2,
+    hasAlpha: true,
+    isPlanar: false,
+    colorSpaceName: .deviceWhite,
+    bytesPerRow: 0,
+    bitsPerPixel: 0
+) else {
+    fatalError("Unable to allocate hero bitmap")
+}
+
+NSGraphicsContext.saveGraphicsState()
+guard let graphicsContext = NSGraphicsContext(bitmapImageRep: bitmap) else {
+    fatalError("Unable to create graphics context")
+}
+NSGraphicsContext.current = graphicsContext
+
+let context = graphicsContext.cgContext
+let canvas = CGRect(x: 0, y: 0, width: canvasWidth, height: canvasHeight)
+context.setAllowsAntialiasing(true)
+context.setShouldAntialias(true)
+context.setFillColor(gray: 0, alpha: 1)
+context.fill(canvas)
+
+// A high-density, fixed-phase interpretation of Aither's Zetesis particle shell.
+// It uses the same latitude sampling, 3D rotation, depth sort and perspective
+// projection as AitherView, scaled for a lossless 3200 × 1280 README asset.
+let latitudeRows = 37
+let phase: CGFloat = 0.17
+let loop = phase * .pi * 2
+let scan = loop * 2
+var particles: [Particle] = []
+
+for row in 0..<latitudeRows {
+    let normalizedRow = CGFloat(row) / CGFloat(latitudeRows - 1)
+    let latitude = (normalizedRow - 0.5) * .pi
+    let ringRadius = cos(latitude)
+    let count = max(18, Int(112 * abs(ringRadius)))
+
+    for index in 0..<count {
+        let longitude = CGFloat(index) / CGFloat(count) * .pi * 2
+        let delta = abs(atan2(sin(longitude - scan), cos(longitude - scan)))
+        let highlight = max(0, 1 - delta / 0.42)
+        particles.append(Particle(
+            x: cos(longitude) * ringRadius,
+            y: sin(latitude),
+            z: sin(longitude) * ringRadius,
+            size: 0.58 + highlight * 0.54,
+            opacity: 0.34 + highlight * 0.66
+        ))
+    }
+}
+
+func rotated(_ point: Particle, x rx: CGFloat, y ry: CGFloat, z rz: CGFloat) -> Particle {
+    let x1 = point.x
+    let y1 = point.y * cos(rx) - point.z * sin(rx)
+    let z1 = point.y * sin(rx) + point.z * cos(rx)
+    let x2 = x1 * cos(ry) + z1 * sin(ry)
+    let y2 = y1
+    let z2 = -x1 * sin(ry) + z1 * cos(ry)
+    return Particle(
+        x: x2 * cos(rz) - y2 * sin(rz),
+        y: x2 * sin(rz) + y2 * cos(rz),
+        z: z2,
+        size: point.size,
+        opacity: point.opacity
+    )
+}
+
+let center = CGPoint(x: 2_680, y: 640)
+let radius: CGFloat = 1_085
+let baseDot: CGFloat = 5.2
+
+let rendered = particles
+    .map { rotated($0, x: -0.16, y: loop * 0.12, z: 0.018) }
+    .sorted { $0.z < $1.z }
+
+for particle in rendered {
+    let depth = max(0, min((particle.z + 1.15) / 2.3, 1))
+    let perspective = 1 / max(0.72, 1 - particle.z * 0.2)
+    let point = CGPoint(
+        x: center.x + particle.x * radius * perspective,
+        y: center.y + particle.y * radius * perspective
+    )
+    let dotRadius = baseDot * particle.size * (0.62 + depth * 0.58) * perspective
+    let alpha = max(0.08, min(particle.opacity * (0.12 + depth * 0.88), 1))
+
+    context.setFillColor(gray: 1, alpha: alpha)
+    context.fillEllipse(in: CGRect(
+        x: point.x - dotRadius,
+        y: point.y - dotRadius,
+        width: dotRadius * 2,
+        height: dotRadius * 2
+    ))
+}
+
+let title = "AITHER"
+let titleFont = NSFont.monospacedSystemFont(ofSize: 25, weight: .medium)
+let titleColor = NSColor(white: 1, alpha: 0.82)
+let tracking: CGFloat = 18
+var titleX: CGFloat = 116
+
+for character in title {
+    let glyph = String(character)
+    let attributes: [NSAttributedString.Key: Any] = [
+        .font: titleFont,
+        .foregroundColor: titleColor
+    ]
+    let size = glyph.size(withAttributes: attributes)
+    glyph.draw(at: CGPoint(x: titleX, y: 105), withAttributes: attributes)
+    titleX += size.width + tracking
+}
+
+graphicsContext.flushGraphics()
+NSGraphicsContext.restoreGraphicsState()
+
+guard let png = bitmap.representation(using: .png, properties: [:]) else {
+    fatalError("Unable to encode hero PNG")
+}
+
+try FileManager.default.createDirectory(
+    at: outputURL.deletingLastPathComponent(),
+    withIntermediateDirectories: true
+)
+try png.write(to: outputURL, options: .atomic)
+print(outputURL.path)