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#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
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