技术好文：UEFoliage工具拓展

项目从4.24升级到4.26后 foliage的editor ui布局发生了很大的变化 顺带原项目中加的功能也要简单的移植下。

1.Fix:

UE的植被有个Invalid的标志，即Fix左边的这个小图标，这个是ue的自带功能选出所有的不合法的植被。

合法条件为: FoliageInstance的BaseComponent是否能在规定范围(射线检测)内找到，且误差在5cm内，且附着的BaseComponent与FoliageInstance是否在同一个level中(项目中新加)。

通俗的理解 所谓的不合法是指1.该植被没有附着的地面 2.地面与植被处于不同的level 3.离开地面过高 4.陷入地面过低。

1/2会影响关卡拆分移动重组导致植被的位置出错。3/4在表现上不美观。

不合法的植被是怎么来的。1美术同学的操作，比如为了美观移动某个植被到“空中”。2.拆关卡，静态合批拆合批的操作。

新加的Fix功能的目的即整体处理上面的4个问题。 具体代码与FoliageEdMode.cpp的SelectInvalidInstances相对应。分成2部分。

part1

step1 找到离需要修复的FoliageInstance最近的地面

step2 给FoliageInstance一个新的BaseId

step3 设置一个能够满足5cm误差的ZOffset来完成”对冲“

1 bool FEdModeFoliage::FixInstanceToGround(AInstancedFoliageActor InIFA, float AlignMaxAngle, FFoliageInfo& Mesh, int32 InstanceIdx)

2 {

3 UWorld InWorld = GetWorld();

4

5 FCollisionQueryParams QueryParams(SCENE_QUERY_STAT(FoliageGroundCheck), true);

6 QueryParams.bReturnFaceIndex = false;

7 FCollisionShape SphereShape;

8 SphereShape.SetSphere(0.f);

9 TArray Hits; Hits.Reserve(16);

10 FHitResult HitResult;

11

12 FFoliageInstance& Instance = Mesh.Instances【InstanceIdx】;

13

14 FVector InstanceTraceRange = Instance.GetInstanceWorldTransform().TransformVector(FVector(0.f, 0.f, FOLIAGE_INVALID_TEST_TRACE));

15 FVector Start = Instance.Location + InstanceTraceRange;

16 FVector End = Instance.Location - InstanceTraceRange;

17

18 InWorld->SweepMultiByObjectType(Hits, Start, End, FQuat::Identity, FCollisionObjectQueryParams(ECC_WorldStatic), SphereShape, QueryParams);

19

20 // Find nearest hit

21 float TempDistance = InstanceTraceRange.Size();

22 for (const FHitResult& Hit : Hits)

23 {

24 float HitDistance = (Hit.Location - Instance.Location).Size();

25 if (HitDistance [span style="color: rgba(0, 0, 0, 1)"> TempDistance)

26 {

27 TempDistance = HitDistance;

28 HitResult = Hit;

29 }

30 }

31

32 if (HitResult.bBlockingHit)

33 {

34 UPrimitiveComponent HitComponent = HitResult.Component.Get();

35

36 // Find BSP brush

37 UModelComponent ModelComponent = Cast(HitComponent);

38 if (ModelComponent)

39 {

40 ABrush BrushActor = ModelComponent->GetModel()->FindBrush(HitResult.Location);

41 if (BrushActor)

42 {

43 HitComponent = BrushActor->GetBrushComponent();

44 }

45 }

46

47 // Set new base

48 auto NewBaseId = InIFA->InstanceBaseCache.AddInstanceBaseId(Mesh.ShouldAttachToBaseComponent() ? HitComponent : nullptr);

49 Mesh.RemoveFromBaseHash(InstanceIdx);

50 Instance.BaseId = NewBaseId;

51 if (Instance.BaseId == FFoliageInstanceBaseCache::InvalidBaseId)

52 {

53 Instance.BaseComponent = nullptr;

54 }

55 Mesh.AddToBaseHash(InstanceIdx);

56

57 // Set new ZOffset

58 float InstanceZUpOffsetFixLimitThreshold = CVarOffGroundZUpOffsetThreshold.GetValueOnGameThread();

59 float InstanceZDownOffsetFixLimitThreshold = CVarOffGroundZDownOffsetThreshold.GetValueOnGameThread();

60 float InstanceOffGroundLocalThreshold = CVarOffGroundTreshold.GetValueOnGameThread();

61 float InstanceWorldTreshold = Instance.GetInstanceWorldTransform().TransformVector(FVector(0.f, 0.f, InstanceOffGroundLocalThreshold)).Size();

62 float InstanceWorldZUpOffsetFixLimitThreshold = Instance.GetInstanceWorldTransform().TransformVector(FVector(0.f, 0.f, InstanceZUpOffsetFixLimitThreshold)).Size();

63 float InstanceWorldZDownOffsetFixLimitThreshold = Instance.GetInstanceWorldTransform().TransformVector(FVector(0.f, 0.f, InstanceZDownOffsetFixLimitThreshold)).Size();

64

65 FVector InstanceWorldZOffset = Instance.GetInstanceWorldTransform().TransformVector(FVector(0.f, 0.f, Instance.ZOffset));

66 FVector OffsetToGround = Instance.Location - (HitResult.Location + InstanceWorldZOffset);

67 bool bIsUpOffset = OffsetToGround.Z > 0 ? true : false;

68 float DistanceToGround = OffsetToGround.Size();

69

70 if (OffsetToGround.Z >= 0)

71 {

72 if (DistanceToGround > InstanceWorldZUpOffsetFixLimitThreshold)

73 {

74 return false;

75 }

76 if ((DistanceToGround - InstanceWorldTreshold) > KINDA_SMALL_NUMBER)

77 {

78 check(InstanceWorldZUpOffsetFixLimitThreshold > KINDA_SMALL_NUMBER);

79 float ScaleRateLocalToWorld = InstanceZUpOffsetFixLimitThreshold / InstanceWorldZUpOffsetFixLimitThreshold;

80 Instance.ZOffset += DistanceToGround ScaleRateLocalToWorld;

81 }

82 }

83 else

84 {

85 if (DistanceToGround > InstanceWorldZDownOffsetFixLimitThreshold)

86 {

87 return false;

88 }

89 if ((DistanceToGround - InstanceWorldTreshold) > KINDA_SMALL_NUMBER)

90 {

91 check(InstanceWorldZDownOffsetFixLimitThreshold > KINDA_SMALL_NUMBER);

92 float ScaleRateLocalToWorld = InstanceZDownOffsetFixLimitThreshold / InstanceWorldZDownOffsetFixLimitThreshold;

93 Instance.ZOffset -= DistanceToGround ScaleRateLocalToWorld;

94 }

95 }

96 return true;

97 }

98 return false;

99 }

View Code

part2

step1 将植被移到合理的关卡中

1 void FEdModeFoliage::MoveSelectInstancesToCorrectLevel(UWorld InWorld)

2 {

3 GEditor->BeginTransaction(NSLOCTEXT("UnrealEd", "FoliageModeTransaction:MoveSelectInstancesToCorrectLevel", "Move Foliage To Correct Level"));

4 {

5

6 const int32 NumLevels = InWorld->GetNumLevels();

7 for (int32 LevelIdx = 0; LevelIdx < NumLevels; ++LevelIdx)

8 {

9 ULevel Level = InWorld->GetLevel(LevelIdx);

10 AInstancedFoliageActor IFA = AInstancedFoliageActor::GetInstancedFoliageActorForLevel(Level);

11 if (IFA)

12 {

13 bool bFoundSelection = false;

14

15 for (auto& MeshPair : IFA->FoliageInfos)

16 {

17 FFoliageInfo& FoliageInfo = MeshPair.Value;

18

19 if (FoliageInfo.SelectedIndices.Array().Num() > 0)

//代码参考：https://weibo.com/u/7930362378

20 {

21 // Mark actor once we found selection

22 if (!bFoundSelection)

23 {

24 IFA->Modify();

25 bFoundSelection = true;

26 }

27 int InstanceIndex = 0;

28 while (InstanceIndex [span style="color: rgba(0, 0, 0, 1)"> FoliageInfo.Instances.Num())

29 {

30 if (!FixInstanceToCorrectLevel(IFA, MeshPair.Key->AlignMaxAngle, FoliageInfo, InstanceIndex))

31 {

32 InstanceIndex++;

33 }

34 }

35 }

36 }

37 }

38 }

39 }

40 GEditor->EndTransaction();

41 }

View Code

1 bool FEdModeFoliage::FixInstanceToCorrectLevel(AInstancedFoliageActor InIFA, float AlignMaxAngle, FFoliageInfo& Mesh, int32 InstanceIdx)

2 {

3 UWorld InWorld = GetWorld();

4

5 FCollisionQueryParams QueryParams(SCENE_QUERY_STAT(FoliageGroundCheck), true);

6 QueryParams.bReturnFaceIndex = false;

7 FCollisionShape SphereShape;

8 SphereShape.SetSphere(0.f);

9 TArray Hits; Hits.Reserve(16);

10 FHitResult HitResult;

11

12 FFoliageInstance& Instance = Mesh.Instances【InstanceIdx】;

13

14 FVector InstanceTraceRange = Instance.GetInstanceWorldTransform().TransformVector(FVector(0.f, 0.f, FOLIAGE_INVALID_TEST_TRACE));

15 FVector Start = Instance.Location + InstanceTraceRange;

16 FVector End = Instance.Location - InstanceTraceRange;

17

18 InWorld->SweepMultiByObjectType(Hits, Start, End, FQuat::Identity, FCollisionObjectQueryParams(ECC_WorldStatic), SphereShape, QueryParams);

19

20 // Find nearest hit

21 float TempDistance = InstanceTraceRange.Size();

22 for (const FHitResult& Hit : Hits)

23 {

24 float HitDistance = (Hit.Location - Instance.Location).Size();

25 if (HitDistance [span style="color: rgba(0, 0, 0, 1)"> TempDistance)

26 {

27 TempDistance = HitDistance;

28 HitResult = Hit;

29 }

30 }

31

32 if (HitResult.bBlockingHit)

33 {

34 UPrimitiveComponent HitComponent = HitResult.Component.Get();

35

36 if (HitComponent->GetComponentLevel() != InIFA->GetLevel())

37 {

38 TSet InInstanceSet;

39 InInstanceSet.Emplace(InstanceIdx);

40 for (auto& Pair : InIFA->FoliageInfos)

41 {

42 if (&Pair.Value.Get() == &Mesh)

43 {

44 UFoliageType* FoliageType = Pair.Key;

45 InIFA->MoveInstancesToLevel(HitComponent->GetComponentLevel(), InInstanceSet, &Mesh, FoliageType);

46 return true;

47 }

48 }

49 }

50 <span style="color: rg