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/** \file blender/freestyle/intern/view_map/SphericalGrid.cpp
 *  \ingroup freestyle
 *  \brief Class to define a cell grid surrounding the projected image of a scene
 *  \author Alexander Beels
 *  \date 2010-12-19
 */

#include <algorithm>
#include <stdexcept>

#include "SphericalGrid.h"

#include "BKE_global.h"

using namespace std;

namespace Freestyle {

// Helper Classes

// OccluderData
///////////////

// Cell
/////////

SphericalGrid::Cell::Cell() {}

SphericalGrid::Cell::~Cell() {}

void SphericalGrid::Cell::setDimensions(real x, real y, real sizeX, real sizeY)
{
	const real epsilon = 1.0e-06;
	boundary[0] = x - epsilon;
	boundary[1] = x + sizeX + epsilon;
	boundary[2] = y - epsilon;
	boundary[3] = y + sizeY + epsilon;
}

bool SphericalGrid::Cell::compareOccludersByShallowestPoint(const SphericalGrid::OccluderData *a,
                                                            const SphericalGrid::OccluderData *b)
{
	return a->shallowest < b->shallowest;
}

void SphericalGrid::Cell::indexPolygons()
{
	// Sort occluders by their shallowest points.
	sort(faces.begin(), faces.end(), compareOccludersByShallowestPoint);
}

// Iterator
//////////////////

SphericalGrid::Iterator::Iterator(SphericalGrid& grid, Vec3r& center, real /*epsilon*/)
: _target(SphericalGrid::Transform::sphericalProjection(center)), _foundOccludee(false)
{
	// Find target cell
	_cell = grid.findCell(_target);
#if SPHERICAL_GRID_LOGGING
		if (G.debug & G_DEBUG_FREESTYLE) {
			cout << "Searching for occluders of edge centered at " << _target << " in cell [" <<
			        _cell->boundary[0] << ", " << _cell->boundary[1] << ", " << _cell->boundary[2] <<
			        ", " << _cell->boundary[3] << "] (" << _cell->faces.size() << " occluders)" << endl;
		}
#endif

	// Set iterator
	_current = _cell->faces.begin();
}

SphericalGrid::Iterator::~Iterator() {}

// SphericalGrid
/////////////////

SphericalGrid::SphericalGrid(OccluderSource& source, GridDensityProvider& density, ViewMap *viewMap,
                             Vec3r& viewpoint, bool enableQI)
: _viewpoint(viewpoint), _enableQI(enableQI)
{
	if (G.debug & G_DEBUG_FREESTYLE) {
		cout << "Generate Cell structure" << endl;
	}
	// Generate Cell structure
	assignCells(source, density, viewMap);
	if (G.debug & G_DEBUG_FREESTYLE) {
		cout << "Distribute occluders" << endl;
	}
	// Fill Cells
	distributePolygons(source);
	if (G.debug & G_DEBUG_FREESTYLE) {
		cout << "Reorganize cells" << endl;
	}
	// Reorganize Cells
	reorganizeCells();
	if (G.debug & G_DEBUG_FREESTYLE) {
		cout << "Ready to use SphericalGrid" << endl;
	}
}

SphericalGrid::~SphericalGrid() {}

void SphericalGrid::assignCells(OccluderSource& /*source*/, GridDensityProvider& density, ViewMap *viewMap)
{
	_cellSize = density.cellSize();
	_cellsX = density.cellsX();
	_cellsY = density.cellsY();
	_cellOrigin[0] = density.cellOrigin(0);
	_cellOrigin[1] = density.cellOrigin(1);
	if (G.debug & G_DEBUG_FREESTYLE) {
		cout << "Using " << _cellsX << "x" << _cellsY << " cells of size " << _cellSize << " square." << endl;
		cout << "Cell origin: " << _cellOrigin[0] << ", " << _cellOrigin[1] << endl;
	}

	// Now allocate the cell table and fill it with default (empty) cells
	_cells.resize(_cellsX * _cellsY);
	for (cellContainer::iterator i = _cells.begin(), end = _cells.end(); i != end; ++i) {
		(*i) = NULL;
	}

	// Identify cells that will be used, and set the dimensions for each
	ViewMap::fedges_container& fedges = viewMap->FEdges();
	for (ViewMap::fedges_container::iterator f = fedges.begin(), fend = fedges.end(); f != fend; ++f) {
		if ((*f)->isInImage()) {
			Vec3r point = SphericalGrid::Transform::sphericalProjection((*f)->center3d());
			unsigned i, j;
			getCellCoordinates(point, i, j);
			if (_cells[i * _cellsY + j] == NULL) {
				// This is an uninitialized cell
				real x, y, width, height;

				x = _cellOrigin[0] + _cellSize * i;
				width = _cellSize;

				y = _cellOrigin[1] + _cellSize * j;
				height = _cellSize;

				// Initialize cell
				Cell *b = _cells[i * _cellsY + j] = new Cell();
				b->setDimensions(x, y, width, height);
			}
		}
	}
}

void SphericalGrid::distributePolygons(OccluderSource& source)
{
	unsigned long nFaces = 0;
	unsigned long nKeptFaces = 0;

	for (source.begin(); source.isValid(); source.next()) {
		OccluderData *occluder = NULL;

		try {
			if (insertOccluder(source, occluder)) {
				_faces.push_back(occluder);
				++nKeptFaces;
			}
		}
		catch (...) {
			// If an exception was thrown, _faces.push_back() cannot have succeeded. Occluder is not owned by anyone,
			// and must be deleted. If the exception was thrown before or during new OccluderData(), then
			// occluder is NULL, and this delete is harmless.
			delete occluder;
			throw;
		}
		++nFaces;
	}
	if (G.debug & G_DEBUG_FREESTYLE) {
		cout << "Distributed " << nFaces << " occluders.  Retained " << nKeptFaces << "." << endl;
	}
}

void SphericalGrid::reorganizeCells()
{
	// Sort the occluders by shallowest point
	for (vector<Cell*>::iterator i = _cells.begin(), end = _cells.end(); i != end; ++i) {
		if (*i != NULL) {
			(*i)->indexPolygons();
		}
	}
}

void SphericalGrid::getCellCoordinates(const Vec3r& point, unsigned& x, unsigned& y)
{
	x = min(_cellsX - 1, (unsigned) floor (max((double) 0.0f, point[0] - _cellOrigin[0]) / _cellSize));
	y = min(_cellsY - 1, (unsigned) floor (max((double) 0.0f, point[1] - _cellOrigin[1]) / _cellSize));
}

SphericalGrid::Cell *SphericalGrid::findCell(const Vec3r& point)
{
	unsigned x, y;
	getCellCoordinates(point, x, y);
	return _cells[x * _cellsY + y];
}

bool SphericalGrid::orthographicProjection() const
{
	return false;
}

const Vec3r& SphericalGrid::viewpoint() const
{
	return _viewpoint;
}

bool SphericalGrid::enableQI() const
{
	return _enableQI;
}

SphericalGrid::Transform::Transform () : GridHelpers::Transform() {}

Vec3r SphericalGrid::Transform::operator()(const Vec3r& point) const
{
	return sphericalProjection(point);
}

Vec3r SphericalGrid::Transform::sphericalProjection(const Vec3r& M)
{
	Vec3r newPoint;

	newPoint[0] = ::atan(M[0] / M[2]);
	newPoint[1] = ::atan(M[1] / M[2]);
	newPoint[2] = ::sqrt(M[0] * M[0] + M[1] * M[1] + M[2] * M[2]);

	return newPoint;
}

} /* namespace Freestyle */