Minimal perf marks (CPU vs submit split)

// Smallest demonstration of the renderer's CPU vs GPU-submit split.
// Marks are runtime-gated via setPerfMarksEnabled — they are
// available in any build.
import NiiVue from '@niivue/niivue'
import { setPerfMarksEnabled } from '../src/view/NVPerfMarks.ts'

const FRAMES = 100
const WARMUP = 20

const nv = new NiiVue({ isColorbarVisible: false })
await nv.attachToCanvas(gl1)
await nv.loadVolumes([{ url: '/volumes/mni152.nii.gz' }])

const median = (xs) => {
  const s = [...xs].sort((a, b) => a - b)
  return s.length ? s[Math.floor(s.length / 2)] : null
}
const fmt = (n) => (n == null ? '—' : `${n.toFixed(2)} ms`)

runBtn.onclick = async () => {
  runBtn.disabled = true
  statusEl.textContent = 'Measuring...'

  // The renderer emits three named `performance.measure` entries per
  // render() call: render-cpu, render-submit, render-frame. We only
  // need the first two — wall time we can take ourselves.
  const cpu = []
  const submit = []
  const observer = new PerformanceObserver((list) => {
    for (const e of list.getEntries()) {
      if (e.name === 'niivue:render-cpu') cpu.push(e.duration)
      else if (e.name === 'niivue:render-submit') submit.push(e.duration)
    }
  })
  observer.observe({ entryTypes: ['measure'] })

  setPerfMarksEnabled(true)
  for (let i = 0; i < WARMUP; i++) nv.view.render()
  // Drop warmup samples.
  observer.takeRecords()
  cpu.length = 0
  submit.length = 0

  const wall = new Float64Array(FRAMES)
  for (let i = 0; i < FRAMES; i++) {
    const t = performance.now()
    nv.view.render()
    wall[i] = performance.now() - t
  }
  // Let the observer drain any pending entries.
  await new Promise((r) => setTimeout(r, 0))
  setPerfMarksEnabled(false)
  observer.disconnect()

  const wallMed = median(wall)
  const fps = wallMed ? 1000 / wallMed : null
  out.textContent = [
    `frames: ${FRAMES}`,
    `wall   median: ${fmt(wallMed)}    (~${fps == null ? '—' : fps.toFixed(1)} fps)`,
    `cpu    median: ${fmt(median(cpu))}`,
    `submit median: ${fmt(median(submit))}`,
  ].join('\n')
  statusEl.textContent = 'Done.'
  runBtn.disabled = false
}