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| |
| #include "qquickpointattractor_p.h" |
| #include <cmath> |
| #include <QDebug> |
| QT_BEGIN_NAMESPACE |
| /*! |
| \qmltype Attractor |
| \instantiates QQuickAttractorAffector |
| \inqmlmodule QtQuick.Particles |
| \ingroup qtquick-particles |
| \inherits Affector |
| \brief For attracting particles towards a specific point. |
| |
| Note that the size and position of this element affects which particles it affects. |
| The size of the point attracted to is always 0x0, and the location of that point |
| is specified by the pointX and pointY properties. |
| |
| Note that Attractor has the standard Item x,y,width and height properties. |
| Like other affectors, these represent the affected area. They |
| do not represent the 0x0 point which is the target of the attraction. |
| */ |
| |
| |
| /*! |
| \qmlproperty real QtQuick.Particles::PointAttractor::pointX |
| |
| The x coordinate of the attracting point. This is relative |
| to the x coordinate of the Attractor. |
| */ |
| /*! |
| \qmlproperty real QtQuick.Particles::PointAttractor::pointY |
| |
| The y coordinate of the attracting point. This is relative |
| to the y coordinate of the Attractor. |
| */ |
| /*! |
| \qmlproperty real QtQuick.Particles::PointAttractor::strength |
| |
| The pull, in units per second, to be exerted on an item one pixel away. |
| |
| Depending on how the attraction is proportionalToDistance this may have to |
| be very high or very low to have a reasonable effect on particles at a |
| distance. |
| */ |
| /*! |
| \qmlproperty AffectableParameter QtQuick.Particles::Attractor::affectedParameter |
| |
| What attribute of particles is directly affected. |
| \list |
| \li Attractor.Position |
| \li Attractor.Velocity |
| \li Attractor.Acceleration |
| \endlist |
| */ |
| /*! |
| \qmlproperty Proportion QtQuick.Particles::Attractor::proportionalToDistance |
| |
| How the distance from the particle to the point affects the strength of the attraction. |
| |
| \list |
| \li Attractor.Constant |
| \li Attractor.Linear |
| \li Attractor.InverseLinear |
| \li Attractor.Quadratic |
| \li Attractor.InverseQuadratic |
| \endlist |
| */ |
| |
| |
| QQuickAttractorAffector::QQuickAttractorAffector(QQuickItem *parent) : |
| QQuickParticleAffector(parent), m_strength(0.0), m_x(0), m_y(0) |
| , m_physics(Velocity), m_proportionalToDistance(Linear) |
| { |
| } |
| |
| bool QQuickAttractorAffector::affectParticle(QQuickParticleData *d, qreal dt) |
| { |
| if (m_strength == 0.0) |
| return false; |
| qreal dx = m_x+m_offset.x() - d->curX(m_system); |
| qreal dy = m_y+m_offset.y() - d->curY(m_system); |
| qreal r = std::sqrt((dx*dx) + (dy*dy)); |
| qreal theta = std::atan2(dy,dx); |
| qreal ds = 0; |
| switch (m_proportionalToDistance){ |
| case InverseQuadratic: |
| ds = (m_strength / qMax<qreal>(1.,r*r)); |
| break; |
| case InverseLinear: |
| ds = (m_strength / qMax<qreal>(1.,r)); |
| break; |
| case Quadratic: |
| ds = (m_strength * qMax<qreal>(1.,r*r)); |
| break; |
| case Linear: |
| ds = (m_strength * qMax<qreal>(1.,r)); |
| break; |
| default: //also Constant |
| ds = m_strength; |
| } |
| ds *= dt; |
| dx = ds * std::cos(theta); |
| dy = ds * std::sin(theta); |
| qreal vx,vy; |
| switch (m_physics){ |
| case Position: |
| d->x = (d->x + dx); |
| d->y = (d->y + dy); |
| break; |
| case Acceleration: |
| d->setInstantaneousAX(d->ax + dx, m_system); |
| d->setInstantaneousAY(d->ay + dy, m_system); |
| break; |
| case Velocity: //also default |
| default: |
| vx = d->curVX(m_system); |
| vy = d->curVY(m_system); |
| d->setInstantaneousVX(vx + dx, m_system); |
| d->setInstantaneousVY(vy + dy, m_system); |
| } |
| |
| return true; |
| } |
| QT_END_NAMESPACE |
| |
| #include "moc_qquickpointattractor_p.cpp" |