Implementing the octree selection from frustum

libraries/octree/src/ViewFrustum.h

@@ -125,6 +125,9 @@ public:
     float calculateRenderAccuracy(const AABox& bounds, float octreeSizeScale = DEFAULT_OCTREE_SIZE_SCALE, 
                                   int boundaryLevelAdjust = 0) const;
 
+    enum PlaneIndex { TOP_PLANE = 0, BOTTOM_PLANE, LEFT_PLANE, RIGHT_PLANE, NEAR_PLANE, FAR_PLANE, NUM_PLANES };
+
+    const ::Plane* getPlanes() const { return _planes; }
 private:
     // Used for keyhole calculations
     ViewFrustum::location pointInKeyhole(const glm::vec3& point) const;
@@ -160,7 +163,7 @@ private:
     float _fieldOfView = DEFAULT_FIELD_OF_VIEW_DEGREES;
     glm::vec4 _corners[8];
     glm::vec3 _cornersWorld[8];
-    enum { TOP_PLANE = 0, BOTTOM_PLANE, LEFT_PLANE, RIGHT_PLANE, NEAR_PLANE, FAR_PLANE };
+ //   enum { TOP_PLANE = 0, BOTTOM_PLANE, LEFT_PLANE, RIGHT_PLANE, NEAR_PLANE, FAR_PLANE };
     ::Plane _planes[6]; // How will this be used?
 
     const char* debugPlaneName (int plane) const;

libraries/render/src/render/DrawSceneOctree.cpp

@@ -80,6 +80,11 @@ void DrawSceneOctree::run(const SceneContextPointer& sceneContext,
         return;
     }
 
+    // Try that:
+    render::ItemIDs items;
+    scene->getSpatialTree().select(items, *args->_viewFrustum);
+
+
     // Allright, something to render let's do it
     gpu::doInBatch(args->_context, [&](gpu::Batch& batch) {
         glm::mat4 projMat;

libraries/render/src/render/Octree.cpp

@@ -10,6 +10,8 @@
 //
 #include "Octree.h"
 
+#include <ViewFrustum.h>
+
 
 using namespace render;
 
@@ -68,7 +70,7 @@ Octree::Location Octree::Location::evalFromRange(const Coord3& minCoord, const C
 }
 
 Octree::Indices Octree::indexConcreteCellPath(const Locations& path) const {
-    Index currentIndex = ROOT;
+    Index currentIndex = ROOT_CELL;
     Indices cellPath(1, currentIndex);
 
     for (int l = 1; l < path.size(); l++) {
@@ -217,3 +219,114 @@ ItemSpatialTree::Index ItemSpatialTree::resetItem(Index oldCell, const Location&
     }
 }
 
+int ItemSpatialTree::select(ItemIDs& selection, const ViewFrustum& frustum) const {
+    auto worldPlanes = frustum.getPlanes();
+    Coord4f planes[6];
+    for (int i = 0; i < ViewFrustum::NUM_PLANES; i++) {
+        ::Plane octPlane;
+        octPlane.setNormalAndPoint(worldPlanes[i].getNormal(), evalCoordf(worldPlanes[i].getPoint(), ROOT_DEPTH));
+        planes[i] = Coord4f(octPlane.getNormal(), octPlane.getDCoefficient());
+    }
+    return Octree::select(selection, planes);
+}
+
+int Octree::select(ItemIDs& selection, const glm::vec4 frustum[6]) const {
+
+    Index cellID = ROOT_CELL;
+    selectTraverse(cellID, selection, frustum);
+    return selection.size();
+}
+
+int Octree::selectTraverse(Index cellID, ItemIDs& selection, const Coord4f frustum[6]) const {
+    int numItemsIn = selection.size();
+    auto cell = getConcreteCell(cellID);
+
+    auto intersection = Octree::Location::intersectCell(cell.getlocation(), frustum);
+    switch (intersection) {
+        case Octree::Location::Outside:
+            // cell is outside, stop traversing this branch
+            return 0;
+            break;
+        case Octree::Location::Inside: {
+            // traverse all the Cell Branch and collect items in the selection
+            selection.push_back(cellID);
+            break;
+        }
+        case Octree::Location::Intersect:
+        default: {
+            // Cell is partially in
+            selection.push_back(cellID);
+
+            // Collect the items of this cell
+
+            // then traverse further
+            for (int i = 0; i < NUM_OCTANTS; i++) {
+                Index subCellID = cell.child((Link)i);
+                if (subCellID != INVALID) {
+                    selectTraverse(subCellID, selection, frustum);
+                }
+            }
+        }
+    }
+
+    return selection.size() - numItemsIn;
+}
+
+
+Octree::Location::Intersection Octree::Location::intersectCell(const Location& cell, const Coord4f frustum[6]) {
+    const Coord3f CornerOffsets[8] = {
+        { 0.0, 0.0, 0.0 },
+        { 1.0, 0.0, 0.0 },
+        { 0.0, 1.0, 0.0 },
+        { 1.0, 1.0, 0.0 },
+        { 0.0, 0.0, 1.0 },
+        { 1.0, 0.0, 1.0 },
+        { 0.0, 1.0, 1.0 },
+        { 1.0, 1.0, 1.0 },
+    };
+
+    struct Tool {
+        static int normalToIndex(const Coord3f& n) {
+            int index = 0;
+            if (n.x >= 0.0) index |= 1;
+            if (n.y >= 0.0) index |= 2;
+            if (n.z >= 0.0) index |= 4;
+            return index;
+        }
+
+        static bool halfPlaneTest(const Coord4f& plane, const Coord3f& pos) {
+            return (glm::dot(plane, Coord4f(pos, 1.0f)) >= 0.0f);
+        }
+    };
+
+    Coord3f cellSize = Coord3f(Octree::getInvDepthDimension(cell.depth));
+    Coord3f cellPos = Coord3f(cell.pos) * cellSize;
+
+    bool partialFlag = false;
+    for (int p = 0; p < ViewFrustum::NUM_PLANES; p++) {
+        Coord4f plane = frustum[p];
+        Coord3f planeNormal(plane);
+
+        int index = Tool::normalToIndex(planeNormal);
+
+        auto negTestPoint = cellPos + cellSize * CornerOffsets[index];
+
+        if (!Tool::halfPlaneTest(plane, negTestPoint)) {
+            return Outside;
+        }
+
+        index = Tool::normalToIndex(-planeNormal);
+
+        auto posTestPoint = cellPos + cellSize * CornerOffsets[index];
+
+        if (!Tool::halfPlaneTest(plane, posTestPoint)) {
+            partialFlag = true;
+        }
+    }
+
+    if (partialFlag) {
+        return Intersect;
+    }
+
+    return Inside;
+}

libraries/render/src/render/Octree.h

@@ -85,6 +85,7 @@ namespace render {
 
         // Max depth is 15 => 32Km root down to 1m cells
         using Depth = int8_t;
+        static const Depth ROOT_DEPTH{ 0 };
         static const Depth MAX_DEPTH { 15 };
         static const double INV_DEPTH_DIM[Octree::MAX_DEPTH + 1];
 
@@ -95,6 +96,8 @@ namespace render {
         using Coord = int16_t;
         using Coord3 = glm::i16vec3;
         using Coord4 = glm::i16vec4;
+        using Coord3f = glm::vec3;
+        using Coord4f = glm::vec4;
 
         static Coord depthBitmask(Depth depth) { return Coord(1 << (MAX_DEPTH - depth)); }
 
@@ -122,7 +125,7 @@ namespace render {
 
             Coord3 pos{ 0 };
             uint8_t spare{ 0 };
-            Depth depth{ 0 };
+            Depth depth{ ROOT_DEPTH };
 
             bool operator== (const Location& right) const { return pos == right.pos && depth == right.depth; }
 
@@ -140,13 +143,22 @@ namespace render {
 
             // Eval the location best fitting the specified range
             static Location evalFromRange(const Coord3& minCoord, const Coord3& maxCoord, Depth rangeDepth = MAX_DEPTH);
+
+            // Eval the intersection test against a frustum
+            enum Intersection {
+                Outside = 0,
+                Intersect,
+                Inside,
+            };
+            static Intersection intersectCell(const Location& cell, const Coord4f frustum[6]);
+
         };
         using Locations = Location::vector;
 
         // Cell or Brick Indexing
         using Index = ItemCell; // int32_t
         static const Index INVALID = -1;
-        static const Index ROOT = 0;
+        static const Index ROOT_CELL = 0;
         using Indices = std::vector<Index>;
 
         // the cell description
@@ -230,6 +242,10 @@ namespace render {
             return _bricks[index];
         }
 
+        // Selection and traverse
+        int select(ItemIDs& selection, const Coord4f frustum[6]) const;
+        int selectTraverse(Index cellID, ItemIDs& selection, const Coord4f frustum[6]) const;
+
     protected:
         Index allocateCell(Index parent, const Location& location);
         Index allocateBrick();
@@ -252,6 +268,7 @@ namespace render {
         double _invSize{ 1.0 / _size };
         glm::vec3 _origin{ -16384.0f };
     public:
+        ItemSpatialTree() {}
 
         float getSize() const { return _size; }
         const glm::vec3& getOrigin() const { return _origin; }
@@ -270,7 +287,10 @@ namespace render {
             auto npos = (pos - getOrigin());
             return Coord3(npos * getInvCellWidth(depth));
         }
-
+        Coord3f evalCoordf(const glm::vec3& pos, Depth depth = Octree::MAX_DEPTH) const {
+            auto npos = (pos - getOrigin());
+            return Coord3f(npos * getInvCellWidth(depth));
+        }
 
         // Bound to Location
         AABox evalBound(const Location& loc) const {
@@ -289,7 +309,10 @@ namespace render {
 
         Index resetItem(Index oldCell, const Location& location, const ItemID& item);
 
-        ItemSpatialTree() {}
+        // Selection and traverse
+        int select(ItemIDs& selection, const ViewFrustum& frustum) const;
+
+
     };
 }