Fix affected signal and docs

Signal wasn't being called in its primary usecase, which was to interact
without altering the particles. Docs have been updated to clarify the
usecase as well.

This also updates the position properties of custom affector to more
accurately specify if they caused changes.

Change-Id: Ia411d9e81002443a56ed8bab9232f1aad49a4c5e
Reviewed-by: Yunqiao Yin <charles.yin@nokia.com>

1 files changed, 34 insertions, 12 deletions

diff --git a/src/particles/qquickcustomaffector.cpp b/src/particles/qquickcustomaffector.cpp
index 788e2446b4..72b1536c54 100644
--- a/src/particles/qquickcustomaffector.cpp
+++ b/src/particles/qquickcustomaffector.cpp
@@ -108,7 +108,12 @@ bool QQuickCustomAffector::isAffectConnected()
 
 void QQuickCustomAffector::affectSystem(qreal dt)
 {
-    if (!isAffectConnected()) {
+    //Acts a bit differently, just emits affected for everyone it might affect, when the only thing is connecting to affected(x,y)
+    bool justAffected = (m_acceleration == &m_nullVector
+        && m_speed == &m_nullVector
+        && m_position == &m_nullVector
+        && isAffectedConnected());
+    if (!isAffectConnected() && !justAffected) {
         QQuickParticleAffector::affectSystem(dt);
         return;
     }
@@ -126,6 +131,15 @@ void QQuickCustomAffector::affectSystem(qreal dt)
     if (toAffect.isEmpty())
         return;
 
+    if (justAffected) {
+        foreach (QQuickParticleData* d, toAffect) {//Not postAffect to avoid saying the particle changed
+            if (m_onceOff)
+                m_onceOffed << qMakePair(d->group, d->index);
+            emit affected(d->curX(), d->curY());
+        }
+        return;
+    }
+
     if (m_onceOff)
         dt = 1.0;
 
@@ -167,24 +181,30 @@ bool QQuickCustomAffector::affectParticle(QQuickParticleData *d, qreal dt)
 
     if (m_acceleration != &m_nullVector){
         QPointF pos = m_acceleration->sample(curPos);
+        QPointF curAcc = QPointF(d->curAX(), d->curAY());
         if (m_relative) {
             pos *= dt;
-            pos += QPointF(d->curAX(), d->curAY());
+            pos += curAcc;
+        }
+        if (pos != curAcc) {
+            d->setInstantaneousAX(pos.x());
+            d->setInstantaneousAY(pos.y());
+            changed = true;
         }
-        d->setInstantaneousAX(pos.x());
-        d->setInstantaneousAY(pos.y());
-        changed = true;
     }
 
     if (m_speed != &m_nullVector){
         QPointF pos = m_speed->sample(curPos);
+        QPointF curVel = QPointF(d->curVX(), d->curVY());
         if (m_relative) {
             pos *= dt;
-            pos += QPointF(d->curVX(), d->curVY());
+            pos += curVel;
+        }
+        if (pos != curVel) {
+            d->setInstantaneousVX(pos.x());
+            d->setInstantaneousVY(pos.y());
+            changed = true;
         }
-        d->setInstantaneousVX(pos.x());
-        d->setInstantaneousVY(pos.y());
-        changed = true;
     }
 
     if (m_position != &m_nullVector){
@@ -193,9 +213,11 @@ bool QQuickCustomAffector::affectParticle(QQuickParticleData *d, qreal dt)
             pos *= dt;
             pos += curPos;
         }
-        d->setInstantaneousX(pos.x());
-        d->setInstantaneousY(pos.y());
-        changed = true;
+        if (pos != curPos) {
+            d->setInstantaneousX(pos.x());
+            d->setInstantaneousY(pos.y());
+            changed = true;
+        }
     }
 
     return changed;