GpuOverlay

Remarks

The panel exists so that a cost distribution is noticed rather than measured. Every number here has been available from AppGraphics.GpuFrame since the render graph started emitting a scope per pass, and Samples/13 already prints the same breakdown to its log — but a log line is read by somebody who already suspects something. Three fixes this repository shipped in one week (a 17× screen march, a page-marking pass at 11 % of the frame, a thickness shell that made a hit test meaningless) were each found by reading a breakdown after forming a suspicion. What a log cannot do is show the distribution move as the camera turns.

⚠ Which is why the rows are in the frame's own order and not in cost order. A panel that re-sorts every frame cannot be read while anything is moving: the eye tracks a row's position, and a table whose rows swap places is a table nobody can watch. Cost decides which passes get a row — the most expensive MaxRows of them — and the graph's declaration order decides where each one sits. FrameGraphOverlay makes the identical argument about its colours.

⚠ And why each bar carries a peak that decays rather than a bare instantaneous value. A GPU reading moves by more than ten percent between two frames of a still camera, so an unsmoothed number is unreadable and a smoothed one hides exactly the spike worth seeing. The bar is the smoothed cost and the tick is the worst this pass has been in the last PeakSeconds seconds — so a pass that costs three milliseconds once, while you walk past a wall, leaves a mark that is still there when you look down.

⚠ Two rows exist to stop the panel lying by omission. unattributed is the frame span minus the passes that fill it, which is non-zero when GPU work happens outside any pass the graph ran — a breakdown that does not describe the whole frame. dropped is Dropped, and a non-zero value means the timeline simply stops partway through the frame: the bars that are there look right and the expensive pass somebody opened this for is absent. Neither is a detail; a panel that hid either would make its own incompleteness authoritative.

Here rather than in Vixen.Engine for the reason the assembly exists: GpuFrame is Vixen.Graphics' and IDiagnosticOverlay is Vixen.Engine's, and neither may reference the other. This is the join.

Fields and properties (13)

• public const int MaxRows

  How many passes get a row before the rest are folded into one.

• public const float PeakSeconds

  How long a peak is held before it decays back toward the current cost.

• public string Name

  What the console and the toggles call it. Lower case, no spaces.

• public OverlayAnchor Anchor

  Which corner it is pinned to.

• public bool Enabled

  Whether it is drawn.

• public float Width

  How wide the panel is, in pixels.

• public GpuFrame Frame

  The last frame the GPU finished timing. The host sets this once a frame.

• public int Latency

  How many frames back Frame was recorded.

• public bool Available

  Whether a profiler is attached at all.

• public int Dropped

  How many scopes the frame being recorded could not fit. ⚠ Non-zero is a lie by omission.

• public int DrawnRows

  How many pass rows the last Draw put on screen.

• public float UnattributedFraction

  The share of the frame no pass accounted for, from zero to one.

• public IReadOnlyList<string> VisiblePasses

  Which passes have a row, top to bottom, as of the last Draw.

Methods (3)

• public double PeakOf(string? pass)

  The decaying peak cost of one pass, in milliseconds, or zero if it has no history.

• public void Reset()

  Forgets every smoothed cost and every peak.

• public void Draw(OverlaySurface surface, in GameTime time)

  Draws it.

Used by (2)

• AppGraphicsVixen.App.Hosting
• GpuOverlayTestsVixen.Engine.Renderer.Tests