//--
void
UniformGrid::VAddObjects(const std::vector<ISpatialObject*>& refObjects)
{
// [rad] We need to determine the size of the grid (size of each cell)
int i32Hash;
float f32Diameter;
ISpatialObject* pObject;
// [rad] Iterate through all objects, and find the biggest diameter
std::vector<ISpatialObject*>::const_iterator iter_object;
for(iter_object = refObjects.begin(); iter_object != refObjects.end(); iter_object++)
{
pObject = (*iter_object);
f32Diameter = pObject->VGetRadius() * 2.0f;
if(f32Diameter > m_f32GridSize)
{
// [rad] Found a bigger object, update
m_f32GridSize = f32Diameter;
}
// [rad] We also locally store object pointers, so we could do a bulk update
m_vecObjects.push_back(pObject);
}
// [rad] We'll make it so that cell's is 'x' times as big as the largest object
m_f32GridSize *= s_f32ObjectCellRatio;
// [rad] For each object, determine the cell and insert
for(iter_object = refObjects.begin(); iter_object != refObjects.end(); iter_object++)
{
pObject = (*iter_object);
// [rad] Compute hash for this object - we use object's center to
// determine the proper cell, and then hash that value
i32Hash = ComputeHashValue(m_i32HashBuckets,
static_cast<int>(pObject->VGetPosition().x / m_f32GridSize),
static_cast<int>(pObject->VGetPosition().y / m_f32GridSize),
static_cast<int>(pObject->VGetPosition().z / m_f32GridSize));
// [rad] Insert at the end of this bucket
(m_vecHashBuckets[i32Hash])->InsertObject(pObject);
}
}
//--
void
KDTreeNode::Construct(ISpatialObject* pObjectList, int i32ObjectCount,
const Vector3& refVectorMin, const Vector3& refVectorMax)
{
// [rad] Store voxel info
m_vec3Max = refVectorMax;
m_vec3Min = refVectorMin;
// [rad] Split plane position is already stored
ISpatialObject* pIter = pObjectList;
ISpatialObject* pObjectTemp;
ISpatialObject* pObject;
// [rad] If there are no children, or there's less objects than bins,
// store everything in this node
if(!m_pChildLeft || !m_pChildRight || i32ObjectCount < s_i32BinCount)
{
// [rad] There's no splitpane and position is not important
m_f32SplitPosition = 0.0f;
//m_i32SplitPane = -1;
// [rad] Copy elements...
m_pObjects = pObjectList;
m_i32ObjectCount = i32ObjectCount;
m_i32ObjectTotal = i32ObjectCount;
// [rad] Iterate through all elements and set this node as a containing cell
pIter = m_pObjects;
while(pIter)
{
pIter->VSetCell(this);
pIter = pIter->VGetNext();
}
return;
}
// [rad] Compute sizes
float f32Span = m_vec3Max[m_i32SplitPane] - m_vec3Min[m_i32SplitPane];
float f32BucketSize = f32Span / static_cast<float>(s_i32BinCount);
float f32Offset = -m_vec3Min[m_i32SplitPane];
int i32BinIndex;
int i32Index;
// [rad] Clean prefix sums and previous values
for(i32Index = 0; i32Index < s_i32BinCount; i32Index++)
{
s_vecBins.at(i32Index).first = 0;
s_vecBins.at(i32Index).second = 0;
s_vecSums.at(i32Index).first = 0;
s_vecSums.at(i32Index).second = 0;
}
// [rad] Go linearly through the list and do binning
pIter = pObjectList;
Vector3 vec3Center;
float f32Radius;
while(pIter)
{
// [rad] Get center and radius of this object
vec3Center = pIter->VGetPosition();
f32Radius = pIter->VGetRadius();
// [rad] Increment proper bins
i32BinIndex = static_cast<int>(floorf((f32Offset + vec3Center[m_i32SplitPane] - f32Radius) * s_i32BinCount / f32Span));
s_vecBins[i32BinIndex].first++;
i32BinIndex = static_cast<int>(floorf((f32Offset + vec3Center[m_i32SplitPane] + f32Radius) * s_i32BinCount / f32Span));
s_vecBins[i32BinIndex].second++;
// [rad] iterate to next element in list
pIter = pIter->VGetNext();
}
// [rad] Compute prefix sums
int i32SumMin = 0;
int i32SumMax = 0;
for(i32Index = 0; i32Index < s_i32BinCount; i32Index++)
{
i32SumMin += s_vecBins.at(i32Index).first;
i32SumMax += s_vecBins.at(i32Index).second;
s_vecSums.at(i32Index).first = i32SumMin;
s_vecSums.at(i32Index).second = i32SumMax;
}
// [rad] Compute split candidate
int i32MinDiff = std::numeric_limits<int>::max();
int i32BinDiff;
int i32SplitPosition = 0;
for(i32Index = 0; i32Index < s_i32BinCount; i32Index++)
{
i32BinDiff = abs(s_vecSums.at(i32Index).first - s_vecSums.at(s_i32BinCount - i32Index - 1).second);
if(i32BinDiff < i32MinDiff)
{
// [rad] This is a good candidate
i32MinDiff = i32BinDiff;
i32SplitPosition = i32Index;
}
}
// [rad] Find real split position
//m_f32SplitPosition = ((i32SplitPosition * f32Span) / f32BucketSize) - f32Offset;
m_f32SplitPosition = m_vec3Min[m_i32SplitPane] + i32SplitPosition * f32BucketSize;
// [rad] Now go insert objects into child nodes
ISpatialObject* pObjectListLeft = NULL;
ISpatialObject* pObjectListRight = NULL;
int i32CountLeft = 0;
int i32CountRight = 0;
pIter = pObjectList;
while(pIter)
{
pObject = pIter->VGetNext();
// [rad] Get center and radius of this object
vec3Center = pIter->VGetPosition();
f32Radius = pIter->VGetRadius();
// [rad] Check where this object belongs
if(vec3Center[m_i32SplitPane] + f32Radius <= m_f32SplitPosition)
{
// [rad] Left child
pIter->VSetNext(pObjectListLeft);
pObjectListLeft = pIter;
i32CountLeft++;
}
else if(vec3Center[m_i32SplitPane] - f32Radius >= m_f32SplitPosition)
{
// [rad] Right child
pIter->VSetNext(pObjectListRight);
pObjectListRight = pIter;
i32CountRight++;
}
else
{
pIter->VSetCell(this);
pIter->VSetNext(m_pObjects);
m_pObjects = pIter;
m_i32ObjectCount++;
}
pIter = pObject;
}
// [rad] We'll keep track of how many objects we have in this node
// and in children
m_i32ObjectTotal += i32ObjectCount;
Vector3 vec3Min = refVectorMin;
vec3Min[m_i32SplitPane] = m_f32SplitPosition;
Vector3 vec3Max = refVectorMax;
vec3Max[m_i32SplitPane] = m_f32SplitPosition;
// [rad] Recurse into left child
m_pChildLeft->Construct(pObjectListLeft, i32CountLeft,
refVectorMin, vec3Max);
// [rad] Recurse into right child
m_pChildRight->Construct(pObjectListRight, i32CountRight,
vec3Min, refVectorMax);
}
//--
void
OctreeNode::AddObjects(ISpatialObject* pObjectList, int i32ObjectCount)
{
ISpatialObject* pIter;
ISpatialObject* pObject;
// [rad] Check if we can stop splitting
if(i32ObjectCount < s_i32MinSplitCount)
{
m_pObjects = pObjectList;
pIter = m_pObjects;
while(pIter)
{
pIter->VSetCell(this);
pIter = pIter->VGetNext();
}
m_i32ObjectCount = i32ObjectCount;
return;
}
int i32Index = 0;
ISpatialObject* apChildObjects[8];
int aiChildCounts[8];
for(i32Index = 0; i32Index < 8; i32Index++)
{
apChildObjects[i32Index] = NULL;
aiChildCounts[i32Index] = 0;
}
pIter = pObjectList;
while(pIter)
{
pObject = pIter->VGetNext();
int i32Position = 0;
int i32Straddle = 0;
float f32Radius = pIter->VGetRadius();
Vector3 vec3Center = pIter->VGetPosition();
for(i32Index = 0; i32Index < 3; i32Index++)
{
if(m_vec3Center[i32Index] < vec3Center[i32Index])
{
if(m_vec3Center[i32Index] > vec3Center[i32Index] - f32Radius)
{
// [rad] Straddle occurs
i32Straddle = 1;
break;
}
else
{
i32Position |= (1 << i32Index);
}
}
else
{
if(m_vec3Center[i32Index] < vec3Center[i32Index] + f32Radius)
{
// [rad] Straddle occurs
i32Straddle = 1;
break;
}
}
}
if(!i32Straddle && m_pChildren[i32Position])
{
// [rad] Contained in existing child node
//m_pChildren[i32Position]->AddObject(pObject);
pIter->VSetNext(apChildObjects[i32Position]);
apChildObjects[i32Position] = pIter;
aiChildCounts[i32Position]++;
}
else
{
// [rad] Store this node for fast back-link
pIter->VSetCell(this);
// [rad] Straddling or no child node available
pIter->VSetNext(m_pObjects);
m_pObjects = pIter;
m_i32ObjectCount++;
}
pIter = pObject;
}
// [rad] At this point
for(i32Index = 0; i32Index < 8; i32Index++)
{
// [rad] Delegate to children
if(m_pChildren[i32Index] && aiChildCounts[i32Index])
{
m_pChildren[i32Index]->AddObjects(apChildObjects[i32Index], aiChildCounts[i32Index]);
}
}
}
//--
void
UniformGrid::VUpdate()
{
int i32X1, i32X2;
int i32Y1, i32Y2;
int i32Z1, i32Z2;
int i32Hash;
float f32Delta;
UniformGridHashBucket* pBucket;
std::vector<ISpatialObject*>::iterator iter_object;
for(iter_object = m_vecObjects.begin(); iter_object != m_vecObjects.end(); iter_object++)
{
ISpatialObject* pObject = (*iter_object);
// [rad] Retrieve the bucket in which this object is stored
pBucket = static_cast<UniformGridHashBucket*>(pObject->VGetCell());
// [rad] Retrieve new object position
const Vector3& vec3Position = pObject->VGetPosition();
// [rad] Check if we need bucket update (compute hash)
i32Hash = ComputeHashValue(m_i32HashBuckets,
static_cast<int>(vec3Position.x / m_f32GridSize),
static_cast<int>(vec3Position.y / m_f32GridSize),
static_cast<int>(vec3Position.z / m_f32GridSize));
// [rad] Check if we need to switch buckets
if(m_vecHashBuckets[i32Hash] != pBucket)
{
// [rad] Remove from old bucket
pBucket->RemoveObject(pObject);
// [rad] Add to new (other) bucket
(m_vecHashBuckets[i32Hash])->InsertObject(pObject);
}
// [rad] Update frame
++m_i32FrameCount;
// [rad] Check collisions within the current bucket
pBucket->CheckCollisions(m_i32FrameCount, pObject);
// [rad] Now we need to check adjacent buckets:
// compute all cells which this object might overlap.
// Because initially we picked size for our cells big enough to
// encompass any object, we have to check at most 8 cells (3D).
f32Delta = pObject->VGetRadius() + m_f32GridSize / s_f32ObjectCellRatio + s_f32Epsilon;
i32X1 = static_cast<int>(floorf((vec3Position.x - f32Delta) / m_f32GridSize));
i32X2 = static_cast<int>(ceilf((vec3Position.x + f32Delta) / m_f32GridSize));
i32Y1 = static_cast<int>(floorf((vec3Position.y - f32Delta) / m_f32GridSize));
i32Y2 = static_cast<int>(ceilf((vec3Position.y + f32Delta) / m_f32GridSize));
i32Z1 = static_cast<int>(floorf((vec3Position.z - f32Delta) / m_f32GridSize));
i32Z2 = static_cast<int>(ceilf((vec3Position.z + f32Delta) / m_f32GridSize));
// [rad] Check all grid cells
for(int i32XIndex = i32X1; i32XIndex <= i32X2; i32XIndex++)
{
for(int i32YIndex = i32Y1; i32YIndex <= i32Y2; i32YIndex++)
{
for(int i32ZIndex = i32Z1; i32ZIndex <= i32Z2; i32ZIndex++)
{
i32Hash = ComputeHashValue(m_i32HashBuckets, i32XIndex, i32YIndex, i32ZIndex);
// [rad] Check if we have checked this bucket already
if(m_vecHashBuckets[i32Hash]->GetLastFrame() == m_i32FrameCount)
{
continue;
}
// [rad] Otherwise check collisions
(m_vecHashBuckets[i32Hash])->CheckCollisions(m_i32FrameCount, pObject);
}
}
}
}
}
