qquickturbulence.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qquickturbulence_p.h"
#include "qquickparticlepainter_p.h"//TODO: Why was this needed again?
#include <cmath>
#include <cstdlib>
#include <QDebug>
#include <QQmlFile>
QT_BEGIN_NAMESPACE
 
QQuickTurbulenceAffector::QQuickTurbulenceAffector(QQuickItem *parent) :
    QQuickParticleAffector(parent),
    m_strength(10), m_gridSize(0), m_field(nullptr), m_vectorField(nullptr), m_inited(false)
{
}
 
void QQuickTurbulenceAffector::geometryChange(const QRectF &, const QRectF &)
{
    initializeGrid();
}
 
QQuickTurbulenceAffector::~QQuickTurbulenceAffector()
{
    if (m_field) {
        for (int i=0; i<m_gridSize; i++)
            free(m_field[i]);
        free(m_field);
    }
    if (m_vectorField) {
        for (int i=0; i<m_gridSize; i++)
            free(m_vectorField[i]);
        free(m_vectorField);
    }
}
 
void QQuickTurbulenceAffector::initializeGrid()
{
    if (!m_inited)
        return;
 
    int arg = qMax(width(), height());
    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);
        }
        if (m_vectorField) {
            for (int i=0; i<m_gridSize; i++)
                free(m_vectorField[i]);
            free(m_vectorField);
        }
        m_gridSize = arg;
    }
 
    m_field = (qreal**)malloc(m_gridSize * sizeof(qreal*));
    for (int i=0; i<m_gridSize; i++)
        m_field[i] = (qreal*)malloc(m_gridSize * sizeof(qreal));
    m_vectorField = (QPointF**)malloc(m_gridSize * sizeof(QPointF*));
    for (int i=0; i<m_gridSize; i++)
        m_vectorField[i] = (QPointF*)malloc(m_gridSize * sizeof(QPointF));
 
    QImage image;
    if (!m_noiseSource.isEmpty())
        image = QImage(QQmlFile::urlToLocalFileOrQrc(m_noiseSource)).scaled(QSize(m_gridSize, m_gridSize));
    if (image.isNull())
        image = QImage(QStringLiteral(":particleresources/noise.png")).scaled(QSize(m_gridSize, m_gridSize));
 
    for (int i=0; i<m_gridSize; i++)
        for (int j=0; j<m_gridSize; j++)
            m_field[i][j] = qGray(image.pixel(QPoint(i,j)));
    for (int i=0; i<m_gridSize; i++){
        for (int j=0; j<m_gridSize; j++){
            m_vectorField[i][j].setX(boundsRespectingField(i-1,j) - boundsRespectingField(i,j));
            m_vectorField[i][j].setY(boundsRespectingField(i,j) - boundsRespectingField(i,j-1));
        }
    }
}
 
qreal QQuickTurbulenceAffector::boundsRespectingField(int x, int y)
{
    if (x < 0)
        x = 0;
    if (x >= m_gridSize)
        x = m_gridSize - 1;
    if (y < 0)
        y = 0;
    if (y >= m_gridSize)
        y = m_gridSize - 1;
    return m_field[x][y];
}
 
void QQuickTurbulenceAffector::ensureInit()
{
    if (m_inited)
        return;
    m_inited = true;
    initializeGrid();
}
 
void QQuickTurbulenceAffector::affectSystem(qreal dt)
{
    if (!m_system || !m_enabled)
        return;
    ensureInit();
    if (!m_gridSize)
        return;
 
    updateOffsets();//### Needed if an ancestor is transformed.
 
    QRect boundsRect(0,0,m_gridSize,m_gridSize);
    for (QQuickParticleGroupData *gd : m_system->groupData) {
        if (!activeGroup(gd->index))
            continue;
        foreach (QQuickParticleData *d, gd->data){
            if (!shouldAffect(d))
                continue;
            QPoint pos = (QPointF(d->curX(m_system), d->curY(m_system)) - m_offset).toPoint();
            if (!boundsRect.contains(pos,true))//Need to redo bounds checking due to quantization.
                continue;
            qreal fx = 0.0;
            qreal fy = 0.0;
            fx += m_vectorField[pos.x()][pos.y()].x() * m_strength;
            fy += m_vectorField[pos.x()][pos.y()].y() * m_strength;
            if (fx || fy){
                d->setInstantaneousVX(d->curVX(m_system)+ fx * dt, m_system);
                d->setInstantaneousVY(d->curVY(m_system)+ fy * dt, m_system);
                postAffect(d);
            }
        }
    }
}
 
QT_END_NAMESPACE
 
#include "moc_qquickturbulence_p.cpp"