EM_Task/UnrealEd/Private/ThumbnailRendering/ParticleSystemThumbnailRenderer.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

#include "ThumbnailRendering/ParticleSystemThumbnailRenderer.h"
#include "Misc/App.h"
#include "UObject/ConstructorHelpers.h"
#include "ShowFlags.h"
#include "SceneView.h"
#include "Editor/UnrealEdEngine.h"
#include "Particles/ParticleSystem.h"
#include "Engine/Texture2D.h"
#include "ThumbnailHelpers.h"
#include "UnrealEdGlobals.h"

// FPreviewScene derived helpers for rendering

#include "CanvasTypes.h"

UParticleSystemThumbnailRenderer::UParticleSystemThumbnailRenderer(const FObjectInitializer& ObjectInitializer)
    : Super(ObjectInitializer)
{
    // Structure to hold one-time initialization
    struct FConstructorStatics
    {
        ConstructorHelpers::FObjectFinder<UTexture2D> PSysThumbnail_NoImage;
        ConstructorHelpers::FObjectFinder<UTexture2D> PSysThumbnail_OOD;
        FConstructorStatics()
            : PSysThumbnail_NoImage(TEXT("/Engine/EditorMaterials/ParticleSystems/PSysThumbnail_NoImage")), PSysThumbnail_OOD(TEXT("/Engine/EditorMaterials/ParticleSystems/PSysThumbnail_OOD"))
        {
        }
    };
    static FConstructorStatics ConstructorStatics;

    NoImage        = ConstructorStatics.PSysThumbnail_NoImage.Object;
    OutOfDate      = ConstructorStatics.PSysThumbnail_OOD.Object;
    ThumbnailScene = nullptr;
}

void UParticleSystemThumbnailRenderer::GetThumbnailSize(UObject* Object, float Zoom, uint32& OutWidth, uint32& OutHeight) const
{
    // Particle system thumbnails will be 1024x1024 at 100%.
    UParticleSystem* PSys = Cast<UParticleSystem>(Object);
    if (PSys != nullptr)
    {
        if ((PSys->bUseRealtimeThumbnail) ||
            (PSys->ThumbnailImage) ||
            (NoImage))
        {
            OutWidth  = FMath::TruncToInt(1024 * Zoom);
            OutHeight = FMath::TruncToInt(1024 * Zoom);
        }
        else
        {
            // Nothing valid to display
            OutWidth = OutHeight = 0;
        }
    }
    else
    {
        OutWidth = OutHeight = 0;
    }
}

void UParticleSystemThumbnailRenderer::Draw(UObject* Object, int32 X, int32 Y, uint32 Width, uint32 Height, FRenderTarget* RenderTarget, FCanvas* Canvas, bool bAdditionalViewFamily)
{
    if (GUnrealEd->GetThumbnailManager())
    {
        UParticleSystem* ParticleSystem = Cast<UParticleSystem>(Object);
        if (ParticleSystem != nullptr)
        {
            if (ParticleSystem->bUseRealtimeThumbnail)
            {
                if (ThumbnailScene == nullptr)
                {
                    ThumbnailScene = new FParticleSystemThumbnailScene();
                }

                ThumbnailScene->SetParticleSystem(ParticleSystem);
                FSceneViewFamilyContext ViewFamily(FSceneViewFamily::ConstructionValues(RenderTarget, ThumbnailScene->GetScene(), FEngineShowFlags(ESFIM_Game))
                                                       .SetWorldTimes(FApp::GetCurrentTime() - GStartTime, FApp::GetDeltaTime(), FApp::GetCurrentTime() - GStartTime)
                                                       .SetAdditionalViewFamily(bAdditionalViewFamily));

                ViewFamily.EngineShowFlags.DisableAdvancedFeatures();
                ViewFamily.EngineShowFlags.MotionBlur = 0;

                ThumbnailScene->GetView(&ViewFamily, X, Y, Width, Height);
                RenderViewFamily(Canvas, &ViewFamily);
                ThumbnailScene->SetParticleSystem(nullptr);
            }
            else if (ParticleSystem->ThumbnailImage)
            {
                Canvas->DrawTile(X, Y, Width, Height, 0.f, 0.f, 1.f, 1.f, FLinearColor::White,
                                 ParticleSystem->ThumbnailImage->Resource, false);
                if (ParticleSystem->ThumbnailImageOutOfDate == true)
                {
                    Canvas->DrawTile(X, Y, Width / 2, Height / 2, 0.f, 0.f, 1.f, 1.f, FLinearColor::White,
                                     OutOfDate->Resource, true);
                }
            }
            else if (NoImage)
            {
                // Use the texture interface to draw
                Canvas->DrawTile(X, Y, Width, Height, 0.f, 0.f, 1.f, 1.f, FLinearColor::White,
                                 NoImage->Resource, false);
            }
        }
    }
}

void UParticleSystemThumbnailRenderer::BeginDestroy()
{
    if (ThumbnailScene != nullptr)
    {
        delete ThumbnailScene;
        ThumbnailScene = nullptr;
    }

    Super::BeginDestroy();
}