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fix(renderer): avoid pure white rain highlights #98

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Merged
patrickschaper merged 1 commit into from
Jun 10, 2026
Merged

fix(renderer): avoid pure white rain highlights #98

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8 changes: 6 additions & 2 deletions Sources/MatrixScreenSaver/NativeMatrixRenderer.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1293,12 +1293,16 @@ final class NativeMatrixRenderer {
}

if minimum + 1 < levels {
// The xterm cube quantizes each channel to 6 steps (0, 95, 135,
// 175, 215, 255). A 0.95 cap still rounds back up to 255, so the
// highlight must stay below 0.9 to avoid pure white.
let highlightCap = 0.89
for level in (minimum + 1)..<levels {
let remaining = Double(levels - 1 - level)
let denominator = Double(levels - 1 - minimum)
let r = 1.0 - (1.0 - Double(red) / edge) * (remaining / denominator)
let r = highlightCap - (highlightCap - Double(red) / edge) * (remaining / denominator)
let g = 1.0 - (1.0 - Double(green) / edge) * (remaining / denominator)
let b = 1.0 - (1.0 - Double(blue) / edge) * (remaining / denominator)
let b = highlightCap - (highlightCap - Double(blue) / edge) * (remaining / denominator)
indices.append(color2index(r, g, b, levels: levels))
}
}
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13 changes: 13 additions & 0 deletions Tests/MatrixScreenSaverTests/NativeMatrixRendererTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,19 @@ func nativeMatrixRendererTests() {
ok(NativeMatrixRenderer().seedOffset == 0,
"NativeMatrixRenderer: seedOffset defaults to 0")

let palette = NativeMatrixRenderer().levelColors
let hasNoPureWhite = !palette.contains { color in
color.red == 255 && color.green == 255 && color.blue == 255
}
ok(hasNoPureWhite,
"NativeMatrixRenderer: palette avoids pure white highlight")

let hasMaxGreenHighlight = palette.contains { color in
color.green == 255
}
ok(hasMaxGreenHighlight,
"NativeMatrixRenderer: palette keeps max-green highlight")

let r1: NativeMatrixRenderer = .init()
let r2: NativeMatrixRenderer = .init()
r1.seedOffset = 0
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