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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::affected(real x, real y)
119 This handler is called when a particle is selected to be affected. It will not be called
120 if a particle is considered by the Affector but not actually altered in any way.
122 In the special case where an Affector has no possible effect (e.g. Affector {}), affected
123 will be emitted for all particles being considered if you connect to it. This allows you to
124 execute arbitrary code in response to particles (see \l affectParticles if you want to execute
125 code which affects the particles themselves) . As this executes JS scritps per particle, it is
126 not recommended to use this signal with a high-volume particle system.
128 x,y is the particles current position.
130 QQuickParticleAffector::QQuickParticleAffector(QQuickItem *parent) :
131 QQuickItem(parent), m_needsReset(false), m_ignoresTime(false), m_onceOff(false), m_enabled(true)
132 , m_system(0), m_updateIntSet(false), m_shape(new QQuickParticleExtruder(this))
136 bool QQuickParticleAffector::isAffectedConnected()
138 IS_SIGNAL_CONNECTED(this, "affected(qreal,qreal)");
142 void QQuickParticleAffector::componentComplete()
144 if (!m_system && qobject_cast<QQuickParticleSystem*>(parentItem()))
145 setSystem(qobject_cast<QQuickParticleSystem*>(parentItem()));
146 QQuickItem::componentComplete();
149 bool QQuickParticleAffector::activeGroup(int g) {
150 if (m_updateIntSet){ //This can occur before group ids are properly assigned, but that resets the flag
152 foreach (const QString &p, m_groups)
153 m_groupIds << m_system->groupIds[p];
154 m_updateIntSet = false;
156 return m_groupIds.isEmpty() || m_groupIds.contains(g);
159 bool QQuickParticleAffector::shouldAffect(QQuickParticleData* d)
163 if (activeGroup(d->group)){
164 if ((m_onceOff && m_onceOffed.contains(qMakePair(d->group, d->index)))
167 //Need to have previous location for affected anyways
168 if (width() == 0 || height() == 0
169 || m_shape->contains(QRectF(m_offset.x(), m_offset.y(), width(), height()), QPointF(d->curX(), d->curY()))){
170 if (m_whenCollidingWith.isEmpty() || isColliding(d)){
179 void QQuickParticleAffector::postAffect(QQuickParticleData* d)
181 m_system->needsReset << d;
183 m_onceOffed << qMakePair(d->group, d->index);
184 if (isAffectedConnected())
185 emit affected(d->curX(), d->curY());
188 const qreal QQuickParticleAffector::simulationDelta = 0.020;
189 const qreal QQuickParticleAffector::simulationCutoff = 1.000;//If this goes above 1.0, then m_once behaviour needs special codepath
191 void QQuickParticleAffector::affectSystem(qreal dt)
195 //If not reimplemented, calls affectParticle per particle
196 //But only on particles in targeted system/area
197 updateOffsets();//### Needed if an ancestor is transformed.
200 foreach (QQuickParticleGroupData* gd, m_system->groupData) {
201 if (activeGroup(m_system->groupData.key(gd))) {
202 foreach (QQuickParticleData* d, gd->data) {
203 if (shouldAffect(d)) {
204 bool affected = false;
206 if (!m_ignoresTime && myDt < simulationCutoff) {
207 int realTime = m_system->timeInt;
208 m_system->timeInt -= myDt * 1000.0;
209 while (myDt > simulationDelta) {
210 m_system->timeInt += simulationDelta * 1000.0;
211 if (d->alive())//Only affect during the parts it was alive for
212 affected = affectParticle(d, simulationDelta) || affected;
213 myDt -= simulationDelta;
215 m_system->timeInt = realTime;
218 affected = affectParticle(d, myDt) || affected;
227 bool QQuickParticleAffector::affectParticle(QQuickParticleData *, qreal )
232 void QQuickParticleAffector::reset(QQuickParticleData* pd)
233 {//TODO: This, among other ones, should be restructured so they don't all need to remember to call the superclass
235 if (activeGroup(pd->group))
236 m_onceOffed.remove(qMakePair(pd->group, pd->index));
239 void QQuickParticleAffector::updateOffsets()
242 m_offset = m_system->mapFromItem(this, QPointF(0, 0));
245 bool QQuickParticleAffector::isColliding(QQuickParticleData *d)
247 qreal myCurX = d->curX();
248 qreal myCurY = d->curY();
249 qreal myCurSize = d->curSize()/2;
250 foreach (const QString &group, m_whenCollidingWith){
251 foreach (QQuickParticleData* other, m_system->groupData[m_system->groupIds[group]]->data){
252 if (!other->stillAlive())
254 qreal otherCurX = other->curX();
255 qreal otherCurY = other->curY();
256 qreal otherCurSize = other->curSize()/2;
257 if ((myCurX + myCurSize > otherCurX - otherCurSize
258 && myCurX - myCurSize < otherCurX + otherCurSize)
259 && (myCurY + myCurSize > otherCurY - otherCurSize
260 && myCurY - myCurSize < otherCurY + otherCurSize))