William Moberg
350 lines
11 KiB
C++
350 lines
11 KiB
C++
#ifndef Octree_h__
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#define Octree_h__
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#include <type_traits>
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#include <bitset>
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#include "../Common.h"
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#include "AABB.h"
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//Fwd declarations.
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class Ray;
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namespace OctSpace
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{
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struct Output;
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struct ContainedObject;
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struct Child;
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}
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//T needs to be AABB, or inherit from AABB.
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//T also needs to have a default constructor.
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template<typename T>
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class Octree
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{
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public:
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Octree() = delete;
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~Octree();
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//For the root Octree, [octreeBounds] should be a box containing the entire level.
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Octree(const AABB& octreeBounds, int subDivisions);
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//We cannot copy the Octree as of now, because of the recursive dynamic allocation.
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//Define these if the Octree suddenly needs to be copied, think of the children Child* ptrs.
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Octree(const Octree& other) = delete;
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Octree(const Octree&& other) = delete;
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Octree& operator= (const Octree& other) = delete;
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//Add a dynamic object (one that moves around) into the tree.
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void AddDynamicObject(const T& object);
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//Add a static object (that does not move) into the tree.
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void AddStaticObject(const T& object);
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//Get the objects that are in the same area as the input [box], the objects are put in [outObjects].
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//The type Box must be AABB, or inherit from AABB.
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template<typename Box>
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void ObjectsInSameRegion(const Box& box, std::vector<T>& outObjects);
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//Get the objects that are inside the frustum defined by the viewProjection matrix, the objects are put in outObjects.
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void ObjectsInFrustum(const glm::mat4x4& viewProj, std::vector<T>& outObjects);
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//Empty the tree of all objects, static and dynamic.
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void ClearObjects();
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//Empty the tree of all dynamic objects. Static objects remain in the tree.
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void ClearDynamicObjects();
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//Returns true if the ray collides with something in the tree. Result is written to [data].
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bool RayCollides(const Ray& ray, OctSpace::Output& data);
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//Returns true if the box collides with something in the tree.
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//On collision with a box, that box is written to [outBoxIntersected].
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//Note: More efficient than calling ObjectsInSameRegion from outside and testing there.
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bool BoxCollides(const AABB& boxToTest, AABB& outBoxIntersected);
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private:
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OctSpace::Child* m_Root;
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std::vector<OctSpace::ContainedObject> m_StaticObjects;
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std::vector<OctSpace::ContainedObject> m_DynamicObjects;
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void falsifyObjectChecks();
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};
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namespace OctSpace
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{
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struct Output
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{
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float CollideDistance;
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};
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//Contains points P in: dot(normal, P) + d = 0
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struct Plane
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{
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glm::vec3 normal;
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float distance;
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};
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//A frustum defined by 6 planes.
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struct Frustum
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{
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enum Output
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{
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Inside,
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Outside,
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Intersects
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};
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Plane planes[6];
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Output VsAABB(const AABB& box) const
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{
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const glm::vec3& maxCorner = box.MaxCorner();
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const glm::vec3& minCorner = box.MinCorner();
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bool completelyInside = true;
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for (const Plane& p : planes) {
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bool anyWasInside = false;
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bool anyWasOutside = false;
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//If points are on both sides of the plane, we can stop.
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for (int i = 0; i < 8 && (!anyWasInside || !anyWasOutside); ++i) {
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std::bitset<3> bits(i);
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glm::vec3 corner;
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corner.x = bits.test(0) ? maxCorner.x : minCorner.x;
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corner.y = bits.test(1) ? maxCorner.y : minCorner.y;
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corner.z = bits.test(2) ? maxCorner.z : minCorner.z;
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if (glm::dot(p.normal, corner) > p.distance) {
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anyWasInside = true;
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} else {
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anyWasOutside = true;
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}
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}
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if (!anyWasInside) {
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return Outside;
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}
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if (anyWasOutside) {
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completelyInside = false;
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}
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}
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return completelyInside ? Inside : Intersects;
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}
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};
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struct ContainedObject
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{
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ContainedObject()
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: Box(nullptr)
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, Checked(false)
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{}
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template<typename BoxlikeObject>
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ContainedObject(const BoxlikeObject& box)
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: Box(new BoxlikeObject(box))
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, Checked(false)
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{}
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std::unique_ptr<AABB> Box;
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bool Checked;
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};
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struct Child
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{
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~Child();
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Child(const AABB& octTreeBounds,
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int subDivisions,
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std::vector<ContainedObject>& staticObjects,
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std::vector<ContainedObject>& dynamicObjects);
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Child(const Child& other) = delete;
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Child(const Child&& other) = delete;
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Child& operator= (const Child& other) = delete;
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void AddDynamicObject(const AABB& box);
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void AddStaticObject(const AABB& box);
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template<typename T, typename Box>
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void ObjectsInSameRegion(const Box& box, std::vector<T>& outObjects) const;
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template<typename T>
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void ObjectsInFrustum(const Frustum& frustum, std::vector<T>& outObjects, bool takeAllDontTest) const;
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void ClearObjects();
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void ClearDynamicObjects();
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bool RayCollides(const Ray& ray, Output& data) const;
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bool BoxCollides(const AABB& boxToTest, AABB& outBoxIntersected) const;
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Child* m_Children[8];
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//Indices into the lists in Octree.
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std::vector<int> m_StaticObjIndices;
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std::vector<int> m_DynamicObjIndices;
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AABB m_Box;
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//Reference to the lists in Octree.
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std::vector<ContainedObject>& m_StaticObjectsRef;
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std::vector<ContainedObject>& m_DynamicObjectsRef;
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inline bool hasChildren() const { return m_Children[0] != nullptr; }
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int childIndexContainingPoint(const glm::vec3& point) const;
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std::vector<int> childIndicesContainingBox(const AABB& box) const;
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};
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}
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template<typename T>
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Octree<T>::Octree(const AABB& octTreeBounds, int subDivisions)
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: m_Root(new OctSpace::Child(octTreeBounds, subDivisions, m_StaticObjects, m_DynamicObjects))
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{
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static_assert(std::is_base_of<AABB, T>::value, "template argument type T in Octree must be a subclass of AABB.");
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}
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template<typename T>
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Octree<T>::~Octree()
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{
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delete m_Root;
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}
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template<typename T>
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void Octree<T>::AddDynamicObject(const T& object)
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{
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m_Root->AddDynamicObject(object);
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m_DynamicObjects.emplace_back(object);
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}
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template<typename T>
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void Octree<T>::AddStaticObject(const T& object)
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{
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m_Root->AddStaticObject(object);
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m_StaticObjects.emplace_back(object);
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}
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template<typename T>
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template<typename Box>
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void Octree<T>::ObjectsInSameRegion(const Box& box, std::vector<T>& outObjects)
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{
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static_assert(std::is_base_of<AABB, Box>::value, "template argument type Box in Octree<T>::ObjectsInSameRegion must be a subclass of AABB.");
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falsifyObjectChecks();
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m_Root->ObjectsInSameRegion(box, outObjects);
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}
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template<typename T>
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void Octree<T>::ObjectsInFrustum(const glm::mat4x4& viewProj, std::vector<T>& outObjects)
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{
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falsifyObjectChecks();
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OctSpace::Frustum frustum;
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for (int i = 0; i < 6; ++i) {
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int sign = 2 * (i % 2) - 1;
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int index = i / 2;
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OctSpace::Plane& plane = frustum.planes[i];
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plane.normal.x = viewProj[0].w + sign * viewProj[0][index];
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plane.normal.y = viewProj[1].w + sign * viewProj[1][index];
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plane.normal.z = viewProj[2].w + sign * viewProj[2][index];
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plane.distance = viewProj[3].w + sign * viewProj[3][index];
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float divByNormalLength = 1.0f / glm::length(plane.normal);
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plane.normal *= divByNormalLength;
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plane.distance *= divByNormalLength;
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}
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m_Root->ObjectsInFrustum(frustum, outObjects, false);
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}
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template<typename T>
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void Octree<T>::ClearObjects()
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{
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m_StaticObjects.clear();
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m_DynamicObjects.clear();
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m_Root->ClearObjects();
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}
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template<typename T>
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void Octree<T>::ClearDynamicObjects()
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{
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m_DynamicObjects.clear();
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m_Root->ClearDynamicObjects();
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}
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template<typename T>
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bool Octree<T>::RayCollides(const Ray& ray, OctSpace::Output& data)
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{
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falsifyObjectChecks();
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data.CollideDistance = -1;
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return m_Root->RayCollides(ray, data);
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}
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template<typename T>
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bool Octree<T>::BoxCollides(const AABB& boxToTest, AABB& outBoxIntersected)
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{
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falsifyObjectChecks();
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return m_Root->BoxCollides(boxToTest, outBoxIntersected);
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}
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template<typename T>
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void Octree<T>::falsifyObjectChecks()
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{
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for (auto& obj : m_StaticObjects) {
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obj.Checked = false;
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}
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for (auto& obj : m_DynamicObjects) {
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obj.Checked = false;
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}
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}
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template<typename T, typename Box>
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void OctSpace::Child::ObjectsInSameRegion(const Box& box, std::vector<T>& outObjects) const
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{
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if (hasChildren()) {
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for (auto i : childIndicesContainingBox(box)) {
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m_Children[i]->ObjectsInSameRegion(box, outObjects);
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}
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} else {
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size_t startIndex = outObjects.size();
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int numDuplicates = 0;
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outObjects.resize(outObjects.size() + m_StaticObjIndices.size() + m_DynamicObjIndices.size());
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for (size_t i = 0; i < m_StaticObjIndices.size(); ++i) {
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ContainedObject& obj = m_StaticObjectsRef[m_StaticObjIndices[i]];
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if (obj.Checked) {
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++numDuplicates;
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} else {
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obj.Checked = true;
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outObjects[startIndex + i - numDuplicates] = *static_cast<T*>(obj.Box.get());
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}
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}
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for (size_t i = 0; i < m_DynamicObjIndices.size(); ++i) {
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ContainedObject& obj = m_DynamicObjectsRef[m_DynamicObjIndices[i]];
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if (obj.Checked) {
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++numDuplicates;
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} else {
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obj.Checked = true;
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outObjects[startIndex + i - numDuplicates] = *static_cast<T*>(obj.Box.get());
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}
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}
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for (size_t i = 0; i < numDuplicates; ++i) {
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outObjects.pop_back();
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}
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}
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}
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template<typename T>
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void OctSpace::Child::ObjectsInFrustum(const Frustum& frustum, std::vector<T>& outObjects, bool takeAllDontTest) const
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{
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if (hasChildren()) {
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for (const Child* c : m_Children) {
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Frustum::Output out = Frustum::Inside;
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if (!takeAllDontTest) {
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out = frustum.VsAABB(c->m_Box);
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if (out == Frustum::Outside) {
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continue;
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}
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}
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c->ObjectsInFrustum(frustum, outObjects, out == Frustum::Inside);
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}
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} else {
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size_t startIndex = outObjects.size();
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int numDuplicates = 0;
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outObjects.resize(outObjects.size() + m_StaticObjIndices.size() + m_DynamicObjIndices.size());
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for (size_t i = 0; i < m_StaticObjIndices.size(); ++i) {
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ContainedObject& obj = m_StaticObjectsRef[m_StaticObjIndices[i]];
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if (obj.Checked || !frustum.VsAABB(obj.Box)) {
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++numDuplicates;
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} else {
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obj.Checked = true;
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outObjects[startIndex + i - numDuplicates] = *static_cast<T*>(obj.Box.get());
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}
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}
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for (size_t i = 0; i < m_DynamicObjIndices.size(); ++i) {
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ContainedObject& obj = m_DynamicObjectsRef[m_DynamicObjIndices[i]];
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if (obj.Checked || !frustum.VsAABB(obj.Box)) {
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++numDuplicates;
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} else {
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obj.Checked = true;
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outObjects[startIndex + i - numDuplicates] = *static_cast<T*>(obj.Box.get());
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}
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}
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for (size_t i = 0; i < numDuplicates; ++i) {
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outObjects.pop_back();
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}
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}
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}
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#endif |