fix(gui): Pace whole-screen fade loop through the frame pacer

[bobtista]

Follow-up to #2840.

The whole-screen fade loop in GameLogic::tryStartNewGame paced itself with a hardcoded Sleep(33). This froze the frame pacer for the duration of the fade, so the frame-rate-decoupled transition step from #2056 (getBaseOverUpdateFpsRatio()) read a stale delta and advanced at a fixed, frame-rate-dependent rate.

This change replaces the delay with TheFramePacer->update(), which caps the framerate and measures real elapsed time. The fade now advances at a consistent rate, and the magic 33 ms delay is gone now that transition speed is variable.

Todo

• testing
• replicate to Generals

[greptile-apps]

Greptile Summary

Replaces the hardcoded Sleep(33) in the whole-screen fade loop inside tryStartNewGame with TheFramePacer->update(), making the fade advance at a consistent wall-clock rate regardless of frame rate.

• The change is applied symmetrically to both the Generals and Zero Hour (GeneralsMD) variants of GameLogic.cpp.
• TheFramePacer is constructed in GameMain() before the engine initializes and is guaranteed non-null for the entire engine lifetime, so no null-pointer risk exists here.

Confidence Score: 5/5

Safe to merge — two one-line identical fixes with no logic added or removed.

The change swaps a hardcoded OS sleep for the existing frame pacer in a tight transition loop. TheFramePacer is constructed unconditionally in GameMain() before the engine starts and lives for the entire game lifetime, so the call site is safe. The same pattern (TheFramePacer->update() in a tight loop) is already used in GameEngine.cpp. Both game variants are updated identically.

No files require special attention.

Important Files Changed

Filename	Overview
Generals/Code/GameEngine/Source/GameLogic/System/GameLogic.cpp	Single-line fix replacing Sleep(33) with TheFramePacer->update() in the FadeWholeScreen transition loop; the pacer is always initialized before this code runs.
GeneralsMD/Code/GameEngine/Source/GameLogic/System/GameLogic.cpp	Identical fix replicated to the Zero Hour variant; symmetric and consistent with the Generals change.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant GL as GameLogic::tryStartNewGame
    participant TH as TheTransitionHandler
    participant WM as TheWindowManager
    participant D as TheDisplay
    participant FP as TheFramePacer

    GL->>TH: setGroup("FadeWholeScreen")
    loop until isFinished()
        GL->>WM: update()
        alt not finished
            GL->>D: draw()
            GL->>GL: setFPMode()
            GL->>FP: update() [was Sleep(33)]
            Note over FP: Caps FPS + measures<br/>real elapsed time
        end
    end
    GL->>GL: deleteLoadScreen()

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant GL as GameLogic::tryStartNewGame
    participant TH as TheTransitionHandler
    participant WM as TheWindowManager
    participant D as TheDisplay
    participant FP as TheFramePacer

    GL->>TH: setGroup("FadeWholeScreen")
    loop until isFinished()
        GL->>WM: update()
        alt not finished
            GL->>D: draw()
            GL->>GL: setFPMode()
            GL->>FP: update() [was Sleep(33)]
            Note over FP: Caps FPS + measures<br/>real elapsed time
        end
    end
    GL->>GL: deleteLoadScreen()

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_{Reviews (2): Last reviewed commit: "fix(gui): Replicate fade-loop frame pace..." | Re-trigger Greptile}

[Caball009]

Does this work properly? If your fps is 30, this would still sleep for 33 msec, right? That doesn't make sense to me if the menu transition speed is say 15.

[xezon]

I tested this locally and it is waiting for completion of fade to black. I think frame pacing makes sense.

[Caball009]

I tested this locally and it is waiting for completion of fade to black. I think frame pacing makes sense.

Did you test with #2840 and e.g. a window transition speed of 15?

EDIT: I'd expect it to work like this:

X = 1000 / (1000 / (fps * window_speed))
sleep(X)

[xezon]

No I tested with defaults only.

[bobtista]

I tested with speed 1 and render fps 30 and 120, then again with speed 15 and render fps 30 and 120. The speed multiplier works and stays consistent across render speeds.

[bobtista]

I tested this locally and it is waiting for completion of fade to black. I think frame pacing makes sense.

Did you test with #2840 and e.g. a window transition speed of 15?

EDIT: I'd expect it to work like this:

X = 1000 / (1000 / (fps * window_speed))
sleep(X)

I think that sleep(X) formula assumes the old model, fixed 1 frame per iteration, vary the sleep to control speed. The fade now advances a fixed number of transition-frames per real second regardless of frame rate eg at 120 fps it steps ~4× as often but ~4× smaller, and the total wall-clock duration matches 30 fps (just smoother). Duration is frameLength / BaseFps seconds. With #2840 the speed multiplier scales that already-time-normalized step, so speed 15 is 15× faster at any frame rate (frameLength / (BaseFps * speed)), independent of the wait.