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42 #include "qquickparticleaffector_p.h"
44 #include <private/qqmlglobal_p.h>
48 \qmlclass Affector QQuickParticleAffector
49 \inqmlmodule QtQuick.Particles 2
50 \brief Applies alterations to the attributes of logical particles at any
51 point in their lifetime
52 \ingroup qtquick-particles
54 The base Affector does not alter any attributes, but can be used to emit a signal
55 when a particle meets certain conditions.
57 If an affector has a defined size, then it will only affect particles within its size and position on screen.
59 Affectors have different performance characteristics to the other particle system elements. In particular,
60 they have some simplifications to try to maintain a simulation at real-time or faster. When running a system
61 with Affectors, irregular frame timings that grow too large ( > one second per frame) will cause the Affectors
62 to try and cut corners with a faster but less accurate simulation. If the system has multiple affectors the order
63 in which they are applied is not guaranteed, and when simulating larger time shifts they will simulate the whole
64 shift each, which can lead to different results compared to smaller time shifts.
66 Accurate simulation for large numbers of particles (hundreds) with multiple affectors may be possible on some hardware,
67 but on less capable hardware you should expect small irregularties in the simulation as simulates with worse granularity.
70 \qmlproperty ParticleSystem QtQuick.Particles2::Affector::system
71 This is the system which will be affected by the element.
72 If the Affector is a direct child of a ParticleSystem, it will automatically be associated with it.
75 \qmlproperty list<string> QtQuick.Particles2::Affector::groups
76 Which logical particle groups will be affected.
78 If empty, it will affect all particles.
81 \qmlproperty list<string> QtQuick.Particles2::Affector::whenCollidingWith
82 If any logical particle groups are specified here, then the affector
83 will only be triggered if the particle being examined intersects with
84 a particle of one of these groups.
86 This is different from the groups property. The groups property selects which
87 particles might be examined, and if they meet other criteria (including being
88 within the bounds of the Affector, modified by shape) then they will be tested
89 again to see if they intersect with a particles from one of the particle groups
92 By default, no groups are specified.
95 \qmlproperty bool QtQuick.Particles2::Affector::enabled
96 If enabled is set to false, this affector will not affect any particles.
98 Usually this is used to conditionally turn an affector on or off.
100 Default value is true.
103 \qmlproperty bool QtQuick.Particles2::Affector::once
104 If once is set to true, this affector will only affect each particle
105 once in their lifetimes. If the affector normally simulates a continuous
106 effect over time, then it will simulate the effect of one second of time
107 the one instant it affects the particle.
109 Default value is false.
112 \qmlproperty Shape QtQuick.Particles2::Affector::shape
113 If a size has been defined, the shape property can be used to affect a
114 non-rectangular area.
117 \qmlsignal QtQuick.Particles2::Affector::onAffected(x, y)
119 This signal is emitted each time the affector actually affects a particle.
121 x,y are the coordinates of the affected particle, relative to the ParticleSystem.
126 \qmlsignal QtQuick.Particles2::Affector::affectParticle(particle particle, real dt)
128 This handler is called when particles are selected to be affected.
130 dt is the time since the last time it was affected. Use dt to normalize
131 trajectory manipulations to real time.
133 Note that JS is slower to execute, so it is not recommended to use this in
134 high-volume particle systems.
137 \qmlsignal QtQuick.Particles2::Affector::affected(real x, real y)
139 This handler is called when a particle is selected to be affected. It will
140 only be called if signal is set to true.
142 x,y is the particles current position.
144 QQuickParticleAffector::QQuickParticleAffector(QQuickItem *parent) :
145 QQuickItem(parent), m_needsReset(false), m_ignoresTime(false), m_onceOff(false), m_enabled(true)
146 , m_system(0), m_updateIntSet(false), m_shape(new QQuickParticleExtruder(this))
150 bool QQuickParticleAffector::isAffectedConnected()
152 IS_SIGNAL_CONNECTED(this, "affected(qreal,qreal)");
156 void QQuickParticleAffector::componentComplete()
158 if (!m_system && qobject_cast<QQuickParticleSystem*>(parentItem()))
159 setSystem(qobject_cast<QQuickParticleSystem*>(parentItem()));
160 QQuickItem::componentComplete();
163 bool QQuickParticleAffector::activeGroup(int g) {
164 if (m_updateIntSet){ //This can occur before group ids are properly assigned, but that resets the flag
166 foreach (const QString &p, m_groups)
167 m_groupIds << m_system->groupIds[p];
168 m_updateIntSet = false;
170 return m_groupIds.isEmpty() || m_groupIds.contains(g);
173 bool QQuickParticleAffector::shouldAffect(QQuickParticleData* d)
177 if (activeGroup(d->group)){
178 if ((m_onceOff && m_onceOffed.contains(qMakePair(d->group, d->index)))
181 //Need to have previous location for affected anyways
182 if (width() == 0 || height() == 0
183 || m_shape->contains(QRectF(m_offset.x(), m_offset.y(), width(), height()), QPointF(d->curX(), d->curY()))){
184 if (m_whenCollidingWith.isEmpty() || isColliding(d)){
193 void QQuickParticleAffector::postAffect(QQuickParticleData* d)
195 m_system->needsReset << d;
197 m_onceOffed << qMakePair(d->group, d->index);
198 if (isAffectedConnected())
199 emit affected(d->curX(), d->curY());
202 const qreal QQuickParticleAffector::simulationDelta = 0.020;
203 const qreal QQuickParticleAffector::simulationCutoff = 1.000;//If this goes above 1.0, then m_once behaviour needs special codepath
205 void QQuickParticleAffector::affectSystem(qreal dt)
209 //If not reimplemented, calls affectParticle per particle
210 //But only on particles in targeted system/area
211 updateOffsets();//### Needed if an ancestor is transformed.
214 foreach (QQuickParticleGroupData* gd, m_system->groupData) {
215 if (activeGroup(m_system->groupData.key(gd))) {
216 foreach (QQuickParticleData* d, gd->data) {
217 if (shouldAffect(d)) {
218 bool affected = false;
220 if (!m_ignoresTime && myDt < simulationCutoff) {
221 int realTime = m_system->timeInt;
222 m_system->timeInt -= myDt * 1000.0;
223 while (myDt > simulationDelta) {
224 m_system->timeInt += simulationDelta * 1000.0;
225 if (d->alive())//Only affect during the parts it was alive for
226 affected = affectParticle(d, simulationDelta) || affected;
227 myDt -= simulationDelta;
229 m_system->timeInt = realTime;
232 affected = affectParticle(d, myDt) || affected;
241 bool QQuickParticleAffector::affectParticle(QQuickParticleData *, qreal )
246 void QQuickParticleAffector::reset(QQuickParticleData* pd)
247 {//TODO: This, among other ones, should be restructured so they don't all need to remember to call the superclass
249 if (activeGroup(pd->group))
250 m_onceOffed.remove(qMakePair(pd->group, pd->index));
253 void QQuickParticleAffector::updateOffsets()
256 m_offset = m_system->mapFromItem(this, QPointF(0, 0));
259 bool QQuickParticleAffector::isColliding(QQuickParticleData *d)
261 qreal myCurX = d->curX();
262 qreal myCurY = d->curY();
263 qreal myCurSize = d->curSize()/2;
264 foreach (const QString &group, m_whenCollidingWith){
265 foreach (QQuickParticleData* other, m_system->groupData[m_system->groupIds[group]]->data){
266 if (!other->stillAlive())
268 qreal otherCurX = other->curX();
269 qreal otherCurY = other->curY();
270 qreal otherCurSize = other->curSize()/2;
271 if ((myCurX + myCurSize > otherCurX - otherCurSize
272 && myCurX - myCurSize < otherCurX + otherCurSize)
273 && (myCurY + myCurSize > otherCurY - otherCurSize
274 && myCurY - myCurSize < otherCurY + otherCurSize))