OctTree can check if a box collides with a box in the OctTree.

include/Engine/Core/OctTree.h

@@ -20,17 +20,21 @@ public:
     void ClearBoxes();
     //Returns true if the ray collides with something in the tree. Result is written to [data].
     bool RayCollides(const Ray& ray, Output& data) const;
+    //Returns true if the box collides with something in the tree. 
+    //On collision with a box, that box is written to [outBoxIntersected].
+    bool BoxCollides(const AABB& boxToTest, AABB& outBoxIntersected) const;
 
 private:
     OctTree* m_Children[8];
-    std::vector<AABB> m_ContainingBoxes;
     //TODO: Do derived class from AABB with a bool Tested, falsify at 
     //start of Collision test, set on check, don't check if set already. Solves duplicate boxes in tree.
+    //TODO: Boxes collide with themselves? Fix somehow, maybe float epsilon stuff.
+    std::vector<AABB> m_ContainingBoxes;
     AABB m_Box;
 
-    bool rayCollides(const Ray& ray, Output& data) const;
     inline bool hasChildren() const;
     int childIndexContainingPoint(const glm::vec3& point) const;
+    std::vector<int> childIndicesContainingBox(const AABB& box) const;
 };
 
 #endif

src/Engine/Core/OctTree.cpp

@@ -80,14 +80,25 @@ OctTree::~OctTree()
     }
 }
 
-bool OctTree::RayCollides(const Ray& ray, Output& data) const
+bool OctTree::BoxCollides(const AABB& boxToTest, AABB& outBoxIntersected) const
 {
-    data.CollideDistance = -1;
+    if (hasChildren()) {
-    return rayCollides(ray, data);
+        for (int i : childIndicesContainingBox(boxToTest)) {
+            if (m_Children[i]->BoxCollides(boxToTest, outBoxIntersected))
+                return true;
+        }
+    } else {
+        for (const auto& objBox : m_ContainingBoxes) {
+            if (Collision::AABBVsAABB(boxToTest, objBox)) {
+                outBoxIntersected = objBox;
+                return true;
+            }
+        }
+    }
+    return false;
 }
 
-//Currently all Nodes must have exactly 0 or 8 children, and objectdata should only exist in the last bottom nodes.
+bool OctTree::RayCollides(const Ray& ray, Output& data) const
-bool OctTree::rayCollides(const Ray& ray, Output& data) const
 {
     //If the node AABB is missed, everything it contains is missed.
     if (Collision::RayAABBIntr(ray, m_Box)) {
@@ -102,7 +113,7 @@ bool OctTree::rayCollides(const Ray& ray, Output& data) const
             std::sort(childInfos.begin(), childInfos.end(), isFirstLower);
             //Loop through the children, starting with the one closest to the ray origin. I.e the first to be hit.
             for (const ChildInfo& info : childInfos) {
-                if (m_Children[info.Index]->rayCollides(ray, data)) {
+                if (m_Children[info.Index]->RayCollides(ray, data)) {
                     return true;
                 }
             }
@@ -127,39 +138,8 @@ bool OctTree::rayCollides(const Ray& ray, Output& data) const
 void OctTree::AddBox(const AABB& box)
 {
     if (hasChildren()) {
-        int minInd = childIndexContainingPoint(box.MinCorner());
+        for (auto i : childIndicesContainingBox(box)) {
-        int maxInd = childIndexContainingPoint(box.MaxCorner());
+            m_Children[i]->AddBox(box);
-        //Because of the predictable ordering of the child indices, 
-        //the number of bits set when xor:ing the indices will determine the number of children containing the box.
-        std::bitset<3> bits(minInd ^ maxInd);
-        switch (bits.count()) {
-        case 0:                         //Box contained completely in one child.
-            m_Children[minInd]->AddBox(box);
-            break;
-        case 1:                         //Two children.
-            m_Children[minInd]->AddBox(box);
-            m_Children[maxInd]->AddBox(box);
-            break;
-        case 2:                         //Four children.
-            //Bit-hax to calculate the right 4 cildren containing the box.
-            //This works because of the childrens index determine what part of 
-            //the dimensions they are responsible for (which octant).
-            bits.flip();
-            //At this point the bits necessarily have exactly one bit set.
-            for (int c = 0; c < 8; ++c) {
-                //If the child index have the same bit set as the bits, add box to it.
-                if (bits.to_ulong() & c) {
-                    m_Children[c]->AddBox(box);
-                }
-            }
-            break;
-        case 3:                         //Eight children.
-            for (OctTree*& c : m_Children) {
-                c->AddBox(box);
-            }
-            break;
-        default:
-            break;
         }
     } else {
         m_ContainingBoxes.push_back(box);
@@ -196,6 +176,44 @@ int OctTree::childIndexContainingPoint(const glm::vec3& point) const
     return (1 << 2) * (point.x >= c.x) | (1 << 1) * (point.y >= c.y) | (point.z >= c.z);
 }
 
+std::vector<int> OctTree::childIndicesContainingBox(const AABB& box) const
+{
+    int minInd = childIndexContainingPoint(box.MinCorner());
+    int maxInd = childIndexContainingPoint(box.MaxCorner());
+    //Because of the predictable ordering of the child indices, 
+    //the number of bits set when xor:ing the indices will determine the number of children containing the box.
+    std::bitset<3> bits(minInd ^ maxInd);
+    switch (bits.count()) {
+        //Box contained completely in one child.
+    case 0:
+        return{ minInd };
+        //Two children.
+    case 1:
+        return{ minInd, maxInd };
+        //Four children.
+    case 2:
+    {
+        std::vector<int> ret;
+        //Bit-hax to calculate the right 4 cildren containing the box.
+        //This works because of the childrens index determine what part of 
+        //the dimensions they are responsible for (which octant).
+        bits.flip();
+        //At this point the bits necessarily have exactly one bit set.
+        for (int c = 0; c < 8; ++c) {
+            //If the child index have the same bit set as the bits, add box to it.
+            if (bits.to_ulong() & c) {
+                ret.push_back(c);
+            }
+        }
+        return ret;
+    }
+    case 3:                         //Eight children.
+        return{ 0,1,2,3,4,5,6,7 };
+    default:
+        return std::vector<int>();
+    }
+}
+
 inline bool OctTree::hasChildren() const
 {
     return m_Children[0] != nullptr;