关于 Puerts 的性能问题

Puerts 在 UE 开发中提供了一定的便利性，可以用代码的方式写蓝图，但是官方是不推荐这么做的

原话如下

那么这个性能问题究竟有多大呢

这里先用 C++ 写一个测试代码

#include "TestWidget.h"

#include "Blueprint/WidgetBlueprintLibrary.h"
#include "Blueprint/WidgetLayoutLibrary.h"

int32 UTestWidget::NativePaint(const FPaintArgs& Args, const FGeometry& AllottedGeometry,
                               const FSlateRect& MyCullingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId,
                               const FWidgetStyle& InWidgetStyle, bool bParentEnabled) const
{
    FPaintContext Context(AllottedGeometry, MyCullingRect, OutDrawElements, LayerId, InWidgetStyle, bParentEnabled);

    FVector2D ViewportSize = UWidgetLayoutLibrary::GetViewportSize(const_cast<UTestWidget*>(this));

    FVector2D LeftTopPoint = FVector2D(ViewportSize.X * 0.2, ViewportSize.Y * 0.2);
    FVector2D RightTopPoint = FVector2D(ViewportSize.X * 0.8, ViewportSize.Y * 0.2);
    FVector2D LeftBottomPoint = FVector2D(ViewportSize.X * 0.2, ViewportSize.Y * 0.8);
    FVector2D RightBottomPoint = FVector2D(ViewportSize.X * 0.8, ViewportSize.Y * 0.8);

    UWidgetBlueprintLibrary::DrawLine(Context, LeftTopPoint, RightTopPoint);
    UWidgetBlueprintLibrary::DrawLine(Context, RightTopPoint, RightBottomPoint);
    UWidgetBlueprintLibrary::DrawLine(Context, RightBottomPoint, LeftBottomPoint);
    UWidgetBlueprintLibrary::DrawLine(Context, LeftBottomPoint, LeftTopPoint);

    return Super::NativePaint(Args, AllottedGeometry, MyCullingRect, OutDrawElements, LayerId, InWidgetStyle,
                              bParentEnabled);
}

然后用 Unreal Insight 看一下性能数据

只看 Paint 的数据，作为对照组

然后在 TypeScript 实现一样的代码

import { $Ref } from "puerts"
import * as UE from "ue"

class TS_TestWidget extends UE.PuertsWidget
{
    OnPaint(Context: $Ref<UE.PaintContext>): void 
    {
        let ViewportSize = UE.WidgetLayoutLibrary.GetViewportSize(this);

        let LeftTopPoint = new UE.Vector2D(ViewportSize.X * 0.2, ViewportSize.Y * 0.2);
        let RightTopPoint = new UE.Vector2D(ViewportSize.X * 0.8, ViewportSize.Y * 0.2);
        let LeftBottomPoint = new UE.Vector2D(ViewportSize.X * 0.2, ViewportSize.Y * 0.8);
        let RightBottomPoint = new UE.Vector2D(ViewportSize.X * 0.8, ViewportSize.Y * 0.8);

        UE.WidgetBlueprintLibrary.DrawLine(Context, LeftTopPoint, RightTopPoint);
        UE.WidgetBlueprintLibrary.DrawLine(Context, RightTopPoint, RightBottomPoint);
        UE.WidgetBlueprintLibrary.DrawLine(Context, RightBottomPoint, LeftBottomPoint);
        UE.WidgetBlueprintLibrary.DrawLine(Context, LeftBottomPoint, LeftTopPoint);
    }
}
export default TS_TestWidget

跟 C++ 对比，在最慢的时候可以可以达到几十倍的差距，假如有几十个这样的 Widget 同时运行（例如血条），那么肯定是会出现游戏顿卡或者游戏帧数低的情况

所以在 Puerts 中尽量不写每帧都会运行的逻辑，避免因为跨语言调用而造成的性能问题