GPU Visualization Modes

Internals of the shader modes shared between main-window-visualization and spectrum-analyzer-window. See metal-gotchas for cross-cutting Metal pitfalls.

Fire Mode

Flame Styles: Inferno (orange/red), Aurora (green/cyan/purple), Electric (blue/white/purple), Ocean (deep blue/teal/white)

Fire Intensity:

• Mellow — gentle ambient flame, smooth transitions
• Intense — punchy beat-reactive flame, sharp spikes

Audio Reactivity:

• Bass (bands 0–15) — heat injection intensity
• Mids (bands 16–49) — flame sway and motion
• Treble (bands 50–74) — ember sparks

Technical: 128×96 simulation grid with per-column propagation. Two-pass separable Gaussian blur (11H + 11V = 22 samples/pixel vs 121 for a single-pass 11×11). 3 Metal passes:

1. compute propagate_fire (128×96 grid)
2. render flame_blur_h (horizontal blur, fire grid → r16Float intermediate texture at drawable size)
3. render flame_blur_v (vertical blur + color mapping → drawable)

The flameBlurTexture intermediate is lazily created/resized when drawable size changes (flameBlurLastDrawableSize). isPipelineAvailable(.flame) requires all three pipelines. 60 FPS.

Shader file: Visualization/FlameShaders.metal

JWST Mode

Deep space flythrough inspired by James Webb Space Telescope.

Visual Elements:

• 3D perspective star field with 5 depth layers and radial streaking
• JWST 6-axis diffraction flares with authentic spike pattern and chromatic fringing
• Rare, richly colored galaxies/nebula patches
• Giant flare events on major peaks (screen-filling, 5.5s decay)
• JWST color palette: 10-stop gradient (navy → indigo → violet → cream → white)
• Gossamer nebula wisps (transparent gas layers with vertical stretch)

Audio Reactivity:

• Music intensity drives flight speed
• Flare frequency tied to overall dB level
• Flare position aligned to frequency peaks
• Giant flare on strong bass peaks (6s cooldown)
• Stars twinkle with treble energy

Technical: Single render pass with procedural FBM noise, parametric JWST flare function, filmic tone mapping. 60 FPS.

Shader file: Visualization/CosmicShaders.metal

Lightning Mode

GPU lightning storm with fractal bolts mapped to spectrum peaks. 8 color schemes selectable via Left/Right arrows in the spectrum window.

Shader file: Visualization/ElectricityShaders.metal

Matrix Mode

Iconic falling digital rain from The Matrix.

Color Schemes:

• Classic — white head, bright green trail, dark green fade
• Amber — warm white head, amber/orange trail, dark brown fade
• Blue Pill — white head, cyan/electric blue trail, navy fade
• Bloodshot — pink-white head, crimson trail, dark maroon fade
• Neon — magenta-white head, hot magenta trail, purple fade

Intensity:

• Subtle — sparse rain, gentle glow, zen-like ambient
• Intense — dense rain, strong glow, punchy beat reactions

Visual Elements:

• 75 columns mapping to spectrum bands
• Procedural glyph patterns (katakana-inspired)
• Spectrum-driven column speed, brightness, trail length
• Phosphor glow + CRT scanlines
• Reflection pool at bottom 18%
• Beat pulse (bass hits flash white)
• Dramatic awakening (sweep-down on major peaks)

Technical: Single render pass with hash-based segment patterns, multi-stream rain simulation. Phosphor glow samples 8 neighbors (glowRange capped to 1 for both Subtle and Intense). 60 FPS.

Shader file: Visualization/MatrixShaders.metal

Snow Mode

Layered procedural snowfall with spectrum-shaped density, gusting drift, and soft atmospheric haze. Bass-driven wind gusts; flurry-to-blizzard intensity range.

Shader file: Visualization/SnowShaders.metal

EKG Mode

Oscilloscope-style electrocardiogram monitor — pure peak-driven, no BPM or tempo clock.

Visual Elements:

• Procedural P-QRS-T ECG waveform with smooth antialiasing
• Medical monitor grid with fine and major subdivisions
• Phosphor trace, glow, scan head, scanlines, vignette, analog monitor noise
• Each detected audio peak fires one QRS complex at the scan head; flat baseline between peaks
• Per-beat amplitude (the prominence of the detected peak) drives that specific QRS's height — quiet peaks read as small blips, loud peaks tower
• Persistent ping-pong trace texture preserves already-drawn history; only the scan-head region is redrawn
• Wide vertical clamp [0.020, 0.980] plus loudness range mix(0.08, 3.40, sqrt(amp)) gives oscilloscope-like headroom
• Selectable styles: Clinical, Cyan, Amber, Neon, Crimson, Ice

Audio Reactivity:

• Pure peak detector driven directly from .audioPCMDataUpdated. Does not use BPM, aubio tempo, or spectrum energy.
• Detection runs on raw RMS per PCM frame (NOT the perceptual level formula, which saturates at 1.0 on compressed audio and would pin the input flat)
• State machine: tracks rising peak and running valley between bumps. On a rising-to-falling transition, fires a beat with amplitude = (peak − valley) × 2.5 clamped to [0,1]
• Peak-prominence gate (> 0.004) replaces ratio-vs-envelope gating — works at any volume including brick-walled material where absolute peak is pinned at 1.0
• 50 ms refractory (~20 Hz max trigger rate); shared 8-slot ring buffer of (timestamp, amplitude) feeds the shader
• Shader sums QRS gaussians around stored beat timestamps; scan-head glow / noise modulation tracks the perceptual level for separate scan-head pulse feel
• EKG Style appears in the spectrum window context menu and the main-window Visuals menu when EKG is active

Technical: Two-pass Metal path:

1. update pass — scrolls/preserves the persistent trace texture and draws only the scan-head band
2. composite pass — renders the monitor grid, glow, and stored trace

EKGParams packs up to 8 beat timestamps (beatTimes[2] float4 array) and matching amplitudes (beatAmps[2]). Unused slots use sentinel -1000. Shared static ring buffer in SpectrumAnalyzerView (ekgBeatTimeRing / ekgBeatAmpRing) is written from the audio tap thread via ekgRecordBeat under ekgBeatRingLock. Embedded main-window EKG rendering quantizes persistent trace scroll to whole drawable pixels with a fractional carry accumulator, avoiding blur from repeatedly sampling the history texture at subpixel offsets in the 76×16 skin display. The standalone spectrum window keeps fractional scroll because its larger drawable does not show the same softness. 60 FPS.

Shader file: Visualization/EKGShaders.metal

Classic / Enhanced / Ultra (analyzer modes)

Cropped logarithmic source range starting at 48 Hz with low-bass tapers from ~42 Hz. See spectrum-analyzer-window for the analyzer curve details.

Shader file: Visualization/SpectrumShaders.metal