48 lines
1.3 KiB
TypeScript
48 lines
1.3 KiB
TypeScript
export type FpsMetrics = {
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averageFps: number
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low1PctFps: number
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}
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export class FpsTracker {
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private frameDurations: number[] = []
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private firstRenderTime: number | undefined
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private lastRenderTime: number | undefined
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record(durationMs: number): void {
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const now = performance.now()
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if (this.firstRenderTime === undefined) {
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this.firstRenderTime = now
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}
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this.lastRenderTime = now
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this.frameDurations.push(durationMs)
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}
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getMetrics(): FpsMetrics | undefined {
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if (
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this.frameDurations.length === 0 ||
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this.firstRenderTime === undefined ||
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this.lastRenderTime === undefined
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) {
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return undefined
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}
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const totalTimeMs = this.lastRenderTime - this.firstRenderTime
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if (totalTimeMs <= 0) {
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return undefined
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}
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const totalFrames = this.frameDurations.length
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const averageFps = totalFrames / (totalTimeMs / 1000)
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const sorted = this.frameDurations.slice().sort((a, b) => b - a)
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const p99Index = Math.max(0, Math.ceil(sorted.length * 0.01) - 1)
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const p99FrameTimeMs = sorted[p99Index]!
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const low1PctFps = p99FrameTimeMs > 0 ? 1000 / p99FrameTimeMs : 0
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return {
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averageFps: Math.round(averageFps * 100) / 100,
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low1PctFps: Math.round(low1PctFps * 100) / 100,
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}
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}
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}
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