Module perf_overlay 

Performance Overlay — real-time frame time, particle count, GPU utilisation, and per-kit cost breakdown for the editor viewport.

Metrics collected

• Frame time (ms): full round-trip from CPU submit to present.
• CPU time (ms): scene update + command recording only.
• GPU time (ms): measured via timer queries when available.
• FPS: rolling average over the last N frames.
• Particle count: live body + ambient + hair particles this frame.
• Draw calls: number of instanced draw calls issued.
• Kit cost (µs): per-kit CPU evaluation time measured with Instant::now() spans.
• Memory: approximate VRAM and system RAM usage.
• Post-FX passes active: count of enabled post-processing stages.

Display

PerfOverlay::render_text produces a multi-line ASCII string suitable for rendering as glyphs in the editor viewport corner. The display is configurable: compact (one-liner), normal (6 lines), or verbose (full breakdown with kit costs and a mini frame-time graph).

Structs

KitTimings

Per-kit CPU cost in microseconds for the last frame.

PerfOverlay

Full performance overlay state.

PerfThresholds

User-configurable warning thresholds for performance metrics.

RingBuffer

TimeSample

A single frame’s timing data.

Enums

Bottleneck

FrameStatus

PerfOverlayMode