zwitschi
5dd53ac30b
The vehicle floated 3.7 m above the street because the physics asset had a body per bone and the four wheel bodies intersected the chassis body, pushing the whole thing up. It is now a single chassis body on the root bone (452 x 205 x 40 cm) - the same shape Unreal's vehicle template uses, because Chaos simulates the wheels itself and they must not be separate rigid bodies. Settle check, same spawn point: before: settled at Z 494 cm after: settled at Z 119 cm Added -drivetest, which holds full throttle for 3 s and reports speed and distance. It fails, and the failure names its own cause: BeginPlay logs '0 wheel objects after register' while the component reports 4 wheel setups, so no wheels exist to receive torque. Recorded in TODO.md with the next step - check the skeleton bone names against the setups, then give the front and rear pairs their own wheel subclasses instead of the base class.
72 lines
2.5 KiB
C++
72 lines
2.5 KiB
C++
#include "GigLineVehicleBuilder.h"
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#if WITH_EDITOR
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#include "AssetToolsModule.h"
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#include "Engine/SkeletalMesh.h"
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#include "PhysicsAssetUtils.h"
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#include "PhysicsEngine/PhysicsAsset.h"
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#include "PhysicsEngine/BodySetup.h"
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#include "PhysicsEngine/SkeletalBodySetup.h"
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#include "Engine/SkeletalMesh.h"
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#include "UObject/Package.h"
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#endif
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UPhysicsAsset* UGigLineVehicleBuilder::BuildPhysicsAsset(USkeletalMesh* Mesh,
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const FString& PackagePath,
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const FString& AssetName)
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{
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#if WITH_EDITOR
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if (!Mesh)
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{
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UE_LOG(LogTemp, Warning, TEXT("GigLine vehicle: no skeletal mesh given"));
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return nullptr;
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}
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const FString FullName = PackagePath / AssetName;
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UPackage* Package = CreatePackage(*FullName);
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if (!Package)
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{
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UE_LOG(LogTemp, Warning, TEXT("GigLine vehicle: could not create package %s"), *FullName);
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return nullptr;
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}
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UPhysicsAsset* PhysicsAsset = NewObject<UPhysicsAsset>(Package, *AssetName,
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RF_Public | RF_Standalone | RF_Transactional);
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// ONE body on the chassis bone, which is what Unreal's own vehicle template uses.
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// The first attempt let FPhysicsAssetUtils build a body per bone and the car settled
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// 3.7 m above the road: the four wheel bodies were intersecting the chassis body and
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// pushing the whole vehicle up. Chaos drives the wheels itself, so they must not be
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// separate rigid bodies here.
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const FBoxSphereBounds Bounds = Mesh->GetBounds();
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const FVector Extent = Bounds.BoxExtent;
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const FName ChassisBone(TEXT("root"));
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USkeletalBodySetup* Body = NewObject<USkeletalBodySetup>(PhysicsAsset, ChassisBone,
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RF_Public | RF_Transactional);
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Body->BoneName = ChassisBone;
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// A box slightly under the mesh bounds: a body that is exactly the bounds sits on the
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// ground plane and reads as floating because the mesh has wheels below the sills.
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FKBoxElem Box;
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Box.X = Extent.X * 1.9f;
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Box.Y = Extent.Y * 1.8f;
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Box.Z = Extent.Z * 0.55f;
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Box.Center = FVector(0.f, 0.f, -Extent.Z * 0.25f);
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Body->AggGeom.BoxElems.Add(Box);
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PhysicsAsset->SkeletalBodySetups.Add(Body);
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UE_LOG(LogTemp, Warning,
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TEXT("GigLine vehicle: chassis body %.0f x %.0f x %.0f cm on bone '%s'"),
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Box.X, Box.Y, Box.Z, *ChassisBone.ToString());
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PhysicsAsset->MarkPackageDirty();
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UE_LOG(LogTemp, Warning, TEXT("GigLine vehicle: physics asset %s with %d bodies"),
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*FullName, PhysicsAsset->SkeletalBodySetups.Num());
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return PhysicsAsset;
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#else
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UE_LOG(LogTemp, Warning,
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TEXT("GigLine vehicle: physics asset generation is editor-only"));
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return nullptr;
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#endif
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}
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