Files
OpenSpace/modules/multiresvolume/rendering/simpletfbrickselector.cpp
2020-02-14 19:37:06 +01:00

399 lines
15 KiB
C++

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#include <modules/multiresvolume/rendering/simpletfbrickselector.h>
#include <modules/multiresvolume/rendering/tsp.h>
#include <modules/multiresvolume/rendering/histogrammanager.h>
#include <openspace/rendering/transferfunction.h>
#include <ghoul/logging/logmanager.h>
#include <ghoul/misc/assert.h>
namespace {
constexpr const char* _loggerCat = "SimpleTfBrickSelector";
bool compareSplitPoints(const openspace::BrickSelection& a,
const openspace::BrickSelection& b)
{
return a.splitPoints < b.splitPoints;
}
} // namespace
namespace openspace {
SimpleTfBrickSelector::SimpleTfBrickSelector(TSP* tsp, HistogramManager* hm,
TransferFunction* tf, int memoryBudget,
int streamingBudget)
: _tsp(tsp)
, _histogramManager(hm)
, _transferFunction(tf)
, _memoryBudget(memoryBudget)
, _streamingBudget(streamingBudget)
{}
void SimpleTfBrickSelector::setMemoryBudget(int memoryBudget) {
_memoryBudget = memoryBudget;
}
void SimpleTfBrickSelector::setStreamingBudget(int streamingBudget) {
_streamingBudget = streamingBudget;
}
void SimpleTfBrickSelector::selectBricks(int timestep, std::vector<int>& bricks) {
const int numTimeSteps = _tsp->header().numTimesteps;
const int numBricksPerDim = _tsp->header().xNumBricks;
const unsigned int rootNode = 0;
BrickSelection::SplitType splitType;
const float rootSplitPoints = splitPoints(rootNode, splitType);
BrickSelection brickSelection = BrickSelection(
numBricksPerDim,
numTimeSteps,
splitType,
rootSplitPoints
);
std::vector<BrickSelection> priorityQueue;
std::vector<BrickSelection> leafSelections;
std::vector<BrickSelection> temporalSplitQueue;
std::vector<BrickSelection> deadEnds;
if (splitType != BrickSelection::SplitType::None) {
priorityQueue.push_back(brickSelection);
}
else {
leafSelections.push_back(brickSelection);
}
const int totalStreamingBudget = _streamingBudget * numTimeSteps;
int nBricksInMemory = 1;
int nStreamedBricks = 1;
while (nBricksInMemory <= _memoryBudget - 7 && priorityQueue.size() > 0) {
std::pop_heap(priorityQueue.begin(), priorityQueue.end(), compareSplitPoints);
BrickSelection bs = priorityQueue.back();
// TODO: handle edge case when we can only afford temporal splits or no split
// (only 1 spot left)
unsigned int brickIndex = bs.brickIndex;
priorityQueue.pop_back();
if (bs.splitType == BrickSelection::SplitType::Temporal) {
bool pickRightTimeChild = bs.timestepInRightChild(timestep);
// On average on the whole time period, splitting this spatial brick in two
// time steps would generate twice as much streaming. Current number of
// streams of this spatial brick is 2^nTemporalSplits over the whole time
// period.
int newStreams = static_cast<int>(std::pow(2, bs.nTemporalSplits));
// Refining this one more step would require the double amount of streams
if (nStreamedBricks + newStreams > totalStreamingBudget) {
// Reached dead end (streaming budget would be exceeded)
deadEnds.push_back(bs);
break;
}
nStreamedBricks += newStreams;
unsigned int childBrickIndex = pickRightTimeChild ?
_tsp->bstRight(brickIndex) :
_tsp->bstLeft(brickIndex);
BrickSelection::SplitType childSplitType;
float childSplitPoints = splitPoints(childBrickIndex, childSplitType);
BrickSelection childSelection = bs.splitTemporally(
pickRightTimeChild,
childBrickIndex,
childSplitType,
childSplitPoints
);
if (childSplitType != BrickSelection::SplitType::None) {
priorityQueue.push_back(childSelection);
std::push_heap(
priorityQueue.begin(),
priorityQueue.end(),
compareSplitPoints
);
}
else {
leafSelections.push_back(childSelection);
}
}
else if (bs.splitType == BrickSelection::SplitType::Spatial) {
nBricksInMemory += 7; // Remove one and add eight.
unsigned int firstChild = _tsp->firstOctreeChild(brickIndex);
// On average on the whole time period, splitting this spatial brick into
// eight spatial bricks would generate eight times as much streaming. Current
// number of streams of this spatial brick is 2^nTemporalStreams over the
// whole time period.
int newStreams = 7 * static_cast<int>(std::pow(2, bs.nTemporalSplits));
if (nStreamedBricks + newStreams > totalStreamingBudget) {
// Reached dead end (streaming budget would be exceeded)
// However, temporal split might be possible
if (bs.splitType != BrickSelection::SplitType::Temporal) {
bs.splitType = BrickSelection::SplitType::Temporal;
bs.splitPoints = temporalSplitPoints(bs.brickIndex);
}
if (bs.splitPoints > -1) {
temporalSplitQueue.push_back(bs);
}
else {
deadEnds.push_back(bs);
}
break;
}
nStreamedBricks += newStreams;
for (unsigned int i = 0; i < 8; i++) {
unsigned int childBrickIndex = firstChild + i;
BrickSelection::SplitType childSplitType;
float childSplitPoints = splitPoints(childBrickIndex, childSplitType);
BrickSelection childSelection = bs.splitSpatially(
i % 2,
(i / 2) % 2, // abock: this is always 0?
i / 4,
childBrickIndex,
childSplitType,
childSplitPoints
);
if (childSplitType != BrickSelection::SplitType::None) {
priorityQueue.push_back(childSelection);
std::push_heap(
priorityQueue.begin(),
priorityQueue.end(),
compareSplitPoints
);
}
else {
leafSelections.push_back(childSelection);
}
}
}
}
if (nStreamedBricks < totalStreamingBudget) {
while (priorityQueue.size() > 0) {
BrickSelection bs = priorityQueue.back();
if (bs.splitType != BrickSelection::SplitType::Temporal) {
bs.splitType = BrickSelection::SplitType::Temporal;
bs.splitPoints = temporalSplitPoints(bs.brickIndex);
}
priorityQueue.pop_back();
if (bs.splitPoints > -1) {
temporalSplitQueue.push_back(bs);
std::push_heap(
temporalSplitQueue.begin(),
temporalSplitQueue.end(),
compareSplitPoints
);
}
else {
deadEnds.push_back(bs);
}
}
// Keep splitting until it's not possible anymore
while (nStreamedBricks < totalStreamingBudget - 1 &&
temporalSplitQueue.size() > 0)
{
std::pop_heap(
temporalSplitQueue.begin(),
temporalSplitQueue.end(),
compareSplitPoints
);
BrickSelection bs = temporalSplitQueue.back();
temporalSplitQueue.pop_back();
unsigned int brickIndex = bs.brickIndex;
int newStreams = static_cast<int>(std::pow(2, bs.nTemporalSplits));
if (nStreamedBricks + newStreams > totalStreamingBudget) {
// The current best choice would make us exceed the streaming budget, try
// next instead.
deadEnds.push_back(bs);
continue;
}
nStreamedBricks += newStreams;
bool pickRightTimeChild = bs.timestepInRightChild(timestep);
unsigned int childBrickIndex = pickRightTimeChild ?
_tsp->bstRight(brickIndex) :
_tsp->bstLeft(brickIndex);
float childSplitPoints = temporalSplitPoints(childBrickIndex);
if (childSplitPoints > -1) {
BrickSelection childSelection = bs.splitTemporally(
pickRightTimeChild,
childBrickIndex,
BrickSelection::SplitType::Temporal,
childSplitPoints
);
temporalSplitQueue.push_back(childSelection);
std::push_heap(
temporalSplitQueue.begin(),
temporalSplitQueue.end(),
compareSplitPoints
);
}
else {
BrickSelection childSelection = bs.splitTemporally(
pickRightTimeChild,
childBrickIndex,
BrickSelection::SplitType::None, -1
);
deadEnds.push_back(childSelection);
}
}
}
else {
// Write selected inner nodes to brickSelection vector
for (const BrickSelection& bs : priorityQueue) {
writeSelection(bs, bricks);
}
}
// Write selected inner nodes to brickSelection vector
for (const BrickSelection& bs : temporalSplitQueue) {
writeSelection(bs, bricks);
}
for (const BrickSelection& bs : deadEnds) {
writeSelection(bs, bricks);
}
// Write selected leaf nodes to brickSelection vector
for (const BrickSelection& bs : leafSelections) {
writeSelection(bs, bricks);
}
}
float SimpleTfBrickSelector::spatialSplitPoints(unsigned int brickIndex) const {
if (_tsp->isOctreeLeaf(brickIndex)) {
return -1.f;
}
return _brickImportances[brickIndex] * 0.125f;
}
float SimpleTfBrickSelector::temporalSplitPoints(unsigned int brickIndex) const {
if (_tsp->isBstLeaf(brickIndex)) {
return -1.f;
}
return _brickImportances[brickIndex] * 0.5f;
}
float SimpleTfBrickSelector::splitPoints(unsigned int brickIndex,
BrickSelection::SplitType& splitType)
{
float temporalPoints = temporalSplitPoints(brickIndex);
float spatialPoints = spatialSplitPoints(brickIndex);
float splitPoints;
if (spatialPoints > 0 && spatialPoints > temporalPoints) {
splitPoints = spatialPoints;
splitType = BrickSelection::SplitType::Spatial;
}
else if (temporalPoints > 0) {
splitPoints = temporalPoints;
splitType = BrickSelection::SplitType::Temporal;
}
else {
splitPoints = -1;
splitType = BrickSelection::SplitType::None;
}
return splitPoints;
}
bool SimpleTfBrickSelector::calculateBrickImportances() {
if (!_transferFunction) {
return false;
}
size_t tfWidth = _transferFunction->width();
// By changing tfWidth to the correct type size_t, this check is no longer valid since
// size_t is unsigned ---abock
//if (tfWidth <= 0) return false;
/* std::vector<float> gradients(tfWidth - 1);
for (size_t offset = 0; offset < tfWidth - 1; offset++) {
glm::vec4 prevRgba = tf->sample(offset);
glm::vec4 nextRgba = tf->sample(offset + 1);
float colorDifference = glm::distance(prevRgba, nextRgba);
float alpha = (prevRgba.w + nextRgba.w) * 0.5;
gradients[offset] = colorDifference*alpha;
}*/
unsigned int nHistograms = _tsp->numTotalNodes();
_brickImportances = std::vector<float>(nHistograms);
for (unsigned int brickIndex = 0; brickIndex < nHistograms; brickIndex++) {
const Histogram* histogram = _histogramManager->histogram(brickIndex);
if (!histogram->isValid()) {
return false;
}
float dotProduct = 0;
for (size_t i = 0; i < _transferFunction->width(); i++) {
float x = static_cast<float>(i) / static_cast<float>(tfWidth);
float sample = histogram->interpolate(x);
ghoul_assert(sample >= 0, "@MISSING");
dotProduct += sample * _transferFunction->sample(i).w;
}
_brickImportances[brickIndex] = dotProduct;
}
LINFO("Updated brick importances");
return true;
}
int SimpleTfBrickSelector::linearCoords(int x, int y, int z) const {
const TSP::Header& header = _tsp->header();
return x + (header.xNumBricks * y) + (header.xNumBricks * header.yNumBricks * z);
}
void SimpleTfBrickSelector::writeSelection(BrickSelection brickSelection,
std::vector<int>& bricks)
{
BrickCover coveredBricks = brickSelection.cover;
for (int z = coveredBricks.lowZ; z < coveredBricks.highZ; z++) {
for (int y = coveredBricks.lowY; y < coveredBricks.highY; y++) {
for (int x = coveredBricks.lowX; x < coveredBricks.highX; x++) {
bricks[linearCoords(x, y, z)] = brickSelection.brickIndex;
}
}
}
}
} // namespace openspace