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参考文献：
https://wiki.unrealengine.com/Procedural_Mesh_Generation
https://answers.unrealengine.com/questions/100323/how-to-create-spawn-boxes-with-box-brush-in-c.html
https://forums.unrealengine.com/showthread.php?1552-Generate-Procedural-Mesh
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This is a very simple demonstration on how to generate procedural meshes and spawn them in game. It is not to be taken as an example of proper programming technique, but only as an indication to help you generate your own meshes.
You can get this up-to-date demo code in a working UE 4.7 project on GitHub. Please note that this no longer works in 4.8 because Epic added an official component with the same name (UProceduralMeshComponent) and similar functionality.
The following assumes you already have a project created. However, you will need to add RHI, RenderCore and ShaderCore modules in your build file.
PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "RHI", "RenderCore", "ShaderCore" });
The Unreal Engine 4 sources come with a CustomMeshComponent under Engine\Plugins\Runtime\CustomMeshComponent. I had trouble with using it as a plugin (link error), so I have reimplemented it. Essentially, copy the files to your project and rename them GeneratedMeshComponent (.h/.cpp). Replace all occurences of "Custom" to "Generated". You will need to add your project header to the cpp file. Otherwise, the code as I have use it is untouched.
Here they are as they appear in my test project:
// Copyright 1998-2014 Epic Games, Inc. All Rights Reserved.
#pragma once
#include "GeneratedMeshComponent.generated.h"
USTRUCT(BlueprintType)
struct FGeneratedMeshTriangle
{
GENERATED_USTRUCT_BODY()
UPROPERTY(EditAnywhere, Category=Triangle)
FVector Vertex0;
UPROPERTY(EditAnywhere, Category=Triangle)
FVector Vertex1;
UPROPERTY(EditAnywhere, Category=Triangle)
FVector Vertex2;
};
/** Component that allows you to specify custom triangle mesh geometry */
UCLASS(editinlinenew, meta=(BlueprintSpawnableComponent), ClassGroup=Rendering)
class UGeneratedMeshComponent : public UMeshComponent, public IInterface_CollisionDataProvider
{
GENERATED_UCLASS_BODY()
public:
/** Set the geometry to use on this triangle mesh */
UFUNCTION(BlueprintCallable, Category="Components|GeneratedMesh")
bool SetGeneratedMeshTriangles(const TArray<FGeneratedMeshTriangle>& Triangles);
/** Description of collision */
UPROPERTY(BlueprintReadOnly, Category="Collision")
class UBodySetup* ModelBodySetup;
// Begin UMeshComponent interface.
virtual int32 GetNumMaterials() const OVERRIDE;
// End UMeshComponent interface.
// Begin Interface_CollisionDataProvider Interface
virtual bool GetPhysicsTriMeshData(struct FTriMeshCollisionData* CollisionData, bool InUseAllTriData) OVERRIDE;
virtual bool ContainsPhysicsTriMeshData(bool InUseAllTriData) const OVERRIDE;
virtual bool WantsNegXTriMesh() OVERRIDE { return false; }
// End Interface_CollisionDataProvider Interface
// Begin UPrimitiveComponent interface.
virtual FPrimitiveSceneProxy* CreateSceneProxy() OVERRIDE;
virtual class UBodySetup* GetBodySetup() OVERRIDE;
// End UPrimitiveComponent interface.
void UpdateBodySetup();
void UpdateCollision();
private:
// Begin USceneComponent interface.
virtual FBoxSphereBounds CalcBounds(const FTransform & LocalToWorld) const OVERRIDE;
// Begin USceneComponent interface.
/** */
TArray<FGeneratedMeshTriangle> GeneratedMeshTris;
friend class FGeneratedMeshSceneProxy;
};
// Copyright 1998-2014 Epic Games, Inc. All Rights Reserved.
#include "MyProject5.h"
#include "DynamicMeshBuilder.h"
#include "GeneratedMeshComponent.h"
#include "Runtime/Launch/Resources/Version.h" // for ENGINE_xxx_VERSION
/** Vertex Buffer */
class FGeneratedMeshVertexBuffer : public FVertexBuffer
{
public:
TArray<FDynamicMeshVertex> Vertices;
virtual void InitRHI()
{
#if ENGINE_MAJOR_VERSION >= 4 && ENGINE_MINOR_VERSION >= 3
FRHIResourceCreateInfo CreateInfo;
VertexBufferRHI = RHICreateVertexBuffer(Vertices.Num() * sizeof(FDynamicMeshVertex),BUF_Static,CreateInfo);
#else
VertexBufferRHI = RHICreateVertexBuffer(Vertices.Num() * sizeof(FDynamicMeshVertex),NULL,BUF_Static);
#endif
// Copy the vertex data into the vertex buffer.
void* VertexBufferData = RHILockVertexBuffer(VertexBufferRHI,0,Vertices.Num() * sizeof(FDynamicMeshVertex), RLM_WriteOnly);
FMemory::Memcpy(VertexBufferData,Vertices.GetTypedData(),Vertices.Num() * sizeof(FDynamicMeshVertex));
RHIUnlockVertexBuffer(VertexBufferRHI);
}
};
/** Index Buffer */
class FGeneratedMeshIndexBuffer : public FIndexBuffer
{
public:
TArray<int32> Indices;
virtual void InitRHI()
{
#if ENGINE_MAJOR_VERSION >= 4 && ENGINE_MINOR_VERSION >= 3
FRHIResourceCreateInfo CreateInfo;
IndexBufferRHI = RHICreateIndexBuffer(sizeof(int32),Indices.Num() * sizeof(int32),BUF_Static,CreateInfo);
#else
IndexBufferRHI = RHICreateIndexBuffer(sizeof(int32),Indices.Num() * sizeof(int32),NULL,BUF_Static);
#endif
// Write the indices to the index buffer.
void* Buffer = RHILockIndexBuffer(IndexBufferRHI,0,Indices.Num() * sizeof(int32),RLM_WriteOnly);
FMemory::Memcpy(Buffer,Indices.GetTypedData(),Indices.Num() * sizeof(int32));
RHIUnlockIndexBuffer(IndexBufferRHI);
}
};
/** Vertex Factory */
class FGeneratedMeshVertexFactory : public FLocalVertexFactory
{
public:
FGeneratedMeshVertexFactory()
{}
/** Initialization */
void Init(const FGeneratedMeshVertexBuffer* VertexBuffer)
{
check(!IsInRenderingThread());
ENQUEUE_UNIQUE_RENDER_COMMAND_TWOPARAMETER(
InitGeneratedMeshVertexFactory,
FGeneratedMeshVertexFactory*,VertexFactory,this,
const FGeneratedMeshVertexBuffer*,VertexBuffer,VertexBuffer,
{
// Initialize the vertex factory‘s stream components.
DataType NewData;
NewData.PositionComponent = STRUCTMEMBER_VERTEXSTREAMCOMPONENT(VertexBuffer,FDynamicMeshVertex,Position,VET_Float3);
NewData.TextureCoordinates.Add(
FVertexStreamComponent(VertexBuffer,STRUCT_OFFSET(FDynamicMeshVertex,TextureCoordinate),sizeof(FDynamicMeshVertex),VET_Float2)
);
NewData.TangentBasisComponents[0] = STRUCTMEMBER_VERTEXSTREAMCOMPONENT(VertexBuffer,FDynamicMeshVertex,TangentX,VET_PackedNormal);
NewData.TangentBasisComponents[1] = STRUCTMEMBER_VERTEXSTREAMCOMPONENT(VertexBuffer,FDynamicMeshVertex,TangentZ,VET_PackedNormal);
NewData.ColorComponent = STRUCTMEMBER_VERTEXSTREAMCOMPONENT(VertexBuffer, FDynamicMeshVertex, Color, VET_Color);
VertexFactory