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+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the Declarative module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "turbulenceaffector.h"
+#include "particle.h"
+#include <cmath>
+#include <cstdlib>
+#include <QDebug>
+QT_BEGIN_NAMESPACE
+
+TurbulenceAffector::TurbulenceAffector(QSGItem *parent) :
+ ParticleAffector(parent),
+ m_strength(10), m_lastT(0), m_frequency(64), m_gridSize(10), m_field(0), m_inited(false)
+{
+ //TODO: Update grid on size change
+}
+
+TurbulenceAffector::~TurbulenceAffector()
+{
+ if (m_field) {
+ for(int i=0; i<m_gridSize; i++)
+ free(m_field[i]);
+ free(m_field);
+ }
+}
+
+static qreal magnitude(qreal x, qreal y)
+{
+ return sqrt(x*x + y*y);
+}
+
+void TurbulenceAffector::setSize(int arg)
+{
+ if (m_gridSize != arg) {
+ if(m_field){ //deallocate and then reallocate grid
+ for(int i=0; i<m_gridSize; i++)
+ free(m_field[i]);
+ free(m_field);
+ m_system = 0;
+ }
+ m_gridSize = arg;
+ emit sizeChanged(arg);
+ }
+}
+
+void TurbulenceAffector::ensureInit()
+{
+ if(m_inited)
+ return;
+ m_inited = true;
+ m_field = (QPointF**)malloc(m_gridSize * sizeof(QPointF*));
+ for(int i=0; i<m_gridSize; i++)
+ m_field[i] = (QPointF*)malloc(m_gridSize * sizeof(QPointF));
+ for(int i=0; i<m_gridSize; i++)
+ for(int j=0; j<m_gridSize; j++)
+ m_field[i][j] = QPointF();
+ m_spacing = QPointF(width()/m_gridSize, height()/m_gridSize);
+ m_magSum = magnitude(m_spacing.x(), m_spacing.y())*2;
+}
+
+void TurbulenceAffector::mapUpdate()
+{
+ QPoint pos(rand() % m_gridSize, rand() % m_gridSize);
+ QPointF vector(m_strength - (((qreal)rand() / RAND_MAX) * m_strength*2),
+ m_strength - (((qreal)rand() / RAND_MAX) * m_strength*2));
+ for(int i = 0; i < m_gridSize; i++){
+ for(int j = 0; j < m_gridSize; j++){
+ qreal dist = magnitude(i-pos.x(), j-pos.y());
+ m_field[i][j] += vector/(dist + 1);
+ if(magnitude(m_field[i][j].x(), m_field[i][j].y()) > m_strength){
+ //Speed limit
+ qreal theta = atan2(m_field[i][j].y(), m_field[i][j].x());
+ m_field[i][j].setX(m_strength * cos(theta));
+ m_field[i][j].setY(m_strength * sin(theta));
+ }
+ }
+ }
+}
+
+
+void TurbulenceAffector::affectSystem(qreal dt)
+{
+ if(!m_system || !m_active)
+ return;
+ ensureInit();
+ qreal period = 1.0/m_frequency;
+ qreal time = m_system->m_timeInt / 1000.0;
+ while( m_lastT < time ){
+ mapUpdate();
+ m_lastT += period;
+ }
+
+ foreach(ParticleData *d, m_system->m_data){
+ if(!d || !activeGroup(d->group))
+ return;
+ qreal fx = 0.0;
+ qreal fy = 0.0;
+ QPointF pos = QPointF(d->curX() - x(), d->curY() - y());//TODO: Offset
+ QPointF nodePos = QPointF(pos.x() / m_spacing.x(), pos.y() / m_spacing.y());
+ QSet<QPair<int, int> > nodes;
+ nodes << qMakePair((int)ceil(nodePos.x()), (int)ceil(nodePos.y()));
+ nodes << qMakePair((int)ceil(nodePos.x()), (int)floor(nodePos.y()));
+ nodes << qMakePair((int)floor(nodePos.x()), (int)ceil(nodePos.y()));
+ nodes << qMakePair((int)floor(nodePos.x()), (int)floor(nodePos.y()));
+ typedef QPair<int, int> intPair;
+ foreach(const intPair &p, nodes){
+ if(!QRect(0,0,m_gridSize-1,m_gridSize-1).contains(QPoint(p.first, p.second)))
+ continue;
+ qreal dist = magnitude(pos.x() - p.first*m_spacing.x(), pos.y() - p.second*m_spacing.y());//TODO: Mathematically valid
+ fx += m_field[p.first][p.second].x() * ((m_magSum - dist)/m_magSum);//Proportionally weight nodes
+ fy += m_field[p.first][p.second].y() * ((m_magSum - dist)/m_magSum);
+ }
+ if(fx || fy){
+ d->setInstantaneousSX(d->curSX()+ fx * dt);
+ d->setInstantaneousSY(d->curSY()+ fy * dt);
+ m_system->m_needsReset << d;
+ }
+ }
+}
+
+QT_END_NAMESPACE