octree

CMakeLists.txt

@@ -31,6 +31,7 @@ add_executable(Moer
  src/FunctionLayer/Acceleration/Acceleration.cpp
  src/FunctionLayer/Acceleration/EmbreeBVH.cpp
  src/FunctionLayer/Acceleration/Linear.cpp
+ src/FunctionLayer/Acceleration/Octree.cpp
 
  src/FunctionLayer/Integrator/NormalIntegrator.cpp
  src/FunctionLayer/Integrator/DirectIntegrator.cpp

src/FunctionLayer/Acceleration/AABB.cpp

@@ -30,7 +30,16 @@ void AABB::Expand(const Point3f &other) {
  pMax = maxP(pMax, other);
 }
 
-bool AABB::rayIntersect(const Ray &ray, float *tMin, float *tMax) const {
+bool AABB::Overlap(const AABB &other) const {
+ for (int dim = 0; dim < 3; ++dim) {
+ if (pMin[dim] > other.pMax[dim] || pMax[dim] < other.pMin[dim]) {
+ return false;
+ }
+ }
+ return true;
+}
+
+bool AABB::RayIntersect(const Ray &ray, float *tMin, float *tMax) const {
  float tNear = ray.tNear, tFar = ray.tFar;
  for (int i = 0; i < 3; ++i) {
  float invDir = 1.f / ray.direction[i];
@@ -49,4 +58,9 @@ bool AABB::rayIntersect(const Ray &ray, float *tMin, float *tMax) const {
  if (tMax)
  *tMax = tFar;
  return true;
+}
+
+Point3f AABB::Center() const {
+ return Point3f{(pMin[0] + pMax[0]) * .5f, (pMin[1] + pMax[1]) * .5f,
+ (pMin[2] + pMax[2]) * .5f};
 }

src/FunctionLayer/Acceleration/AABB.h

@@ -19,9 +19,13 @@ class AABB {
 
  void Expand(const Point3f &other);
 
- bool rayIntersect(const Ray &ray, float *tMin = nullptr,
+ bool Overlap(const AABB &other) const;
+
+ bool RayIntersect(const Ray &ray, float *tMin = nullptr,
  float *tMax = nullptr) const;
 
+ Point3f Center() const;
+
 public:
  Point3f pMin, pMax;
 };

src/FunctionLayer/Acceleration/Acceleration.cpp

@@ -1,17 +1,20 @@
 #include "Acceleration.h"
 #include "EmbreeBVH.h"
 #include "Linear.h"
-
+#include "Octree.h"
 // Default acceleration type is embree
 AccelerationType Acceleration::type = AccelerationType::Embree;
 
 std::map<std::string, AccelerationType> accelerationTypeMap = {
- {"embree", AccelerationType::Embree}, {"linear", AccelerationType::Linear}};
+ {"embree", AccelerationType::Embree},
+ {"linear", AccelerationType::Linear},
+ {"octree", AccelerationType::Octree}};
 
 std::map<AccelerationType, std::function<std::shared_ptr<Acceleration>()>>
  accelerationBuildMap = {
  {AccelerationType::Embree, std::make_shared<EmbreeBVH>},
- {AccelerationType::Linear, std::make_shared<LinearAcceleration>}};
+ {AccelerationType::Linear, std::make_shared<LinearAcceleration>},
+ {AccelerationType::Octree, std::make_shared<OctreeAcceleration>}};
 
 void Acceleration::setAccelerationType(std::string type) {
  if (accelerationTypeMap.count(type) == 0) {

src/FunctionLayer/Acceleration/Acceleration.h

@@ -5,7 +5,7 @@
 #include <optional>
 #include <vector>
 
-enum class AccelerationType { Embree, Linear };
+enum class AccelerationType { Embree, Linear, Octree };
 
 //* 所有空间加速结构的基类
 class Acceleration {
@@ -42,6 +42,8 @@ class Acceleration {
 public:
  static AccelerationType type;
 
+ AABB boundingBox;
+
 protected:
  std::vector<std::shared_ptr<Shape>> shapes; //* 场景中的所有几何体
 };

src/FunctionLayer/Acceleration/Octree.h

@@ -0,0 +1,39 @@
+#pragma once
+#include "Acceleration.h"
+
+// MAX_LEAF_SIZE表示叶节点中至多包含的shape的个数
+// 若构建时，某个节点的Shape个数多于MAX_LEAF_SIZE，那么就会对该节点继续划分
+
+#define MAX_LEAF_SIZE 64
+
+struct OctreeNode {
+ AABB boundingBox; // 该节点的包围盒
+
+ std::shared_ptr<OctreeNode> subNodes[8]; // 该节点的八个子节点
+
+ // primCount设为-1时表示该节点不是叶节点，primCount为正值时表示叶节点有多少个shape
+ int primCount = -1;
+
+ int primIdxBuffer[MAX_LEAF_SIZE];
+};
+
+//* 八叉树 Octree
+
+class OctreeAcceleration : public Acceleration {
+public:
+ OctreeAcceleration();
+
+ virtual ~OctreeAcceleration();
+
+ virtual void build() override;
+
+ virtual bool rayIntersect(Ray &ray, int *geomID, int *primID, float *u,
+ float *v) const override;
+
+protected:
+ std::shared_ptr<OctreeNode>
+ recursiveBuild(const AABB &aabb, const std::vector<int> &primIdxBuffer);
+
+protected:
+ std::shared_ptr<OctreeNode> root;
+};

src/FunctionLayer/Shape/Triangle.cpp

@@ -157,7 +157,7 @@ void TriangleMesh::fillIntersection(float distance, int primID, float u,
 }
 
 void TriangleMesh::initInternalAcceleration() {
- acceleration = std::make_shared<LinearAcceleration>();
+ acceleration = Acceleration::createAcceleration();
  int primCount = meshData->faceCount;
  for (int primID = 0; primID < primCount; ++primID) {
  int vtx0Idx = meshData->faceBuffer[primID][0].vertexIndex,
@@ -168,5 +168,7 @@ void TriangleMesh::initInternalAcceleration() {
  acceleration->attachShape(triangle);
  }
  acceleration->build();
+ // TriangleMesh的包围盒就是其内部加速结构的包围盒
+ boundingBox = acceleration->boundingBox;
 }
 REGISTER_CLASS(TriangleMesh, "triangle")