Files
FlaxEngine/Source/Engine/Tools/ModelTool/MeshAccelerationStructure.h

135 lines
3.7 KiB
C++

// Copyright (c) Wojciech Figat. All rights reserved.
#pragma once
#if COMPILE_WITH_MODEL_TOOL
#include "Engine/Core/Math/Triangle.h"
#include "Engine/Core/Math/BoundingBox.h"
#include "Engine/Core/Types/DataContainer.h"
#include "Engine/Core/Collections/Array.h"
class Model;
class ModelData;
class GPUBuffer;
/// <summary>
/// Acceleration Structure utility for robust ray tracing mesh geometry with optimized data structure.
/// </summary>
class FLAXENGINE_API MeshAccelerationStructure
{
private:
struct Mesh
{
Model* Asset;
BytesContainer IndexBuffer, VertexBuffer;
int32 Indices, Vertices;
bool Use16BitIndexBuffer;
BoundingBox Bounds;
};
struct BVH
{
BoundingBox Bounds;
union
{
struct
{
uint32 IsLeaf : 1;
uint16 TriangleCount : 15;
uint16 MeshIndex : 16;
uint32 TriangleIndex;
} Leaf;
struct
{
uint32 IsLeaf : 1;
uint32 ChildrenCount : 31;
int32 ChildIndex;
} Node;
};
};
struct BVHBuild
{
int32 MaxLeafSize, MaxDepth;
int32 NodeDepth = 0;
int32 MaxNodeDepth = 0;
int32 MaxNodeTriangles = 0;
Array<byte> Scratch;
};
Array<Mesh, InlinedAllocation<16>> _meshes;
Array<BVH> _bvh;
void BuildBVH(int32 node, BVHBuild& build);
bool PointQueryBVH(int32 node, const Vector3& point, Real& hitDistance, Vector3& hitPoint, Triangle& hitTriangle) const;
bool RayCastBVH(int32 node, const Ray& ray, Real& hitDistance, Vector3& hitNormal, Triangle& hitTriangle) const;
public:
~MeshAccelerationStructure();
// Adds the model geometry for the build to the structure.
void Add(Model* model, int32 lodIndex);
// Adds the model geometry for the build to the structure.
void Add(const ModelData* modelData, int32 lodIndex, bool copy = false);
// Adds the triangles geometry for the build to the structure.
void Add(Float3* vb, int32 vertices, void* ib, int32 indices, bool use16BitIndex, bool copy = false);
// Merges all added meshes into a single mesh (to reduce number of BVH nodes). Required for GPU BVH build.
void MergeMeshes(bool force16BitIndexBuffer = false);
// Builds Bounding Volume Hierarchy (BVH) structure for accelerated geometry queries.
void BuildBVH(int32 maxLeafSize = 16, int32 maxDepth = 0);
// Queries the closest triangle.
bool PointQuery(const Vector3& point, Real& hitDistance, Vector3& hitPoint, Triangle& hitTriangle, Real maxDistance = MAX_Real) const;
// Ray traces the triangles.
bool RayCast(const Ray& ray, Real& hitDistance, Vector3& hitNormal, Triangle& hitTriangle, Real maxDistance = MAX_Real) const;
public:
struct GPU
{
GPUBuffer* BVHBuffer;
GPUBuffer* VertexBuffer;
GPUBuffer* IndexBuffer;
bool Valid;
GPU()
: BVHBuffer(nullptr)
, VertexBuffer(nullptr)
, IndexBuffer(nullptr)
{
}
GPU(GPU&& other) noexcept
: BVHBuffer(other.BVHBuffer)
, VertexBuffer(other.VertexBuffer)
, IndexBuffer(other.IndexBuffer)
{
other.BVHBuffer = nullptr;
other.VertexBuffer = nullptr;
other.IndexBuffer = nullptr;
}
GPU& operator=(GPU other)
{
Swap(*this, other);
return *this;
}
~GPU();
operator bool() const;
};
// Converts the acceleration structure data to GPU format for raytracing inside a shader.
GPU ToGPU();
};
#endif