214 lines
7.3 KiB
C++
214 lines
7.3 KiB
C++
// This file is part of Eigen, a lightweight C++ template library
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// for linear algebra.
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//
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// Copyright (C) 2008 Benoit Jacob <jacob.benoit.1@gmail.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla
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// Public License v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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#include "mandelbrot.h"
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#include <iostream>
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#include<QtGui/QPainter>
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#include<QtGui/QImage>
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#include<QtGui/QMouseEvent>
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#include<QtCore/QTime>
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void MandelbrotWidget::resizeEvent(QResizeEvent *)
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{
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if(size < width() * height())
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{
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std::cout << "reallocate buffer" << std::endl;
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size = width() * height();
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if(buffer) delete[]buffer;
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buffer = new unsigned char[4*size];
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}
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}
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template<typename T> struct iters_before_test { enum { ret = 8 }; };
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template<> struct iters_before_test<double> { enum { ret = 16 }; };
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template<typename Real> void MandelbrotThread::render(int img_width, int img_height)
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{
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enum { packetSize = Eigen::internal::packet_traits<Real>::size }; // number of reals in a Packet
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typedef Eigen::Array<Real, packetSize, 1> Packet; // wrap a Packet as a vector
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enum { iters_before_test = iters_before_test<Real>::ret };
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max_iter = (max_iter / iters_before_test) * iters_before_test;
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const int alignedWidth = (img_width/packetSize)*packetSize;
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unsigned char *const buffer = widget->buffer;
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const double xradius = widget->xradius;
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const double yradius = xradius * img_height / img_width;
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const int threadcount = widget->threadcount;
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typedef Eigen::Array<Real, 2, 1> Vector2;
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Vector2 start(widget->center.x() - widget->xradius, widget->center.y() - yradius);
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Vector2 step(2*widget->xradius/img_width, 2*yradius/img_height);
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total_iter = 0;
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for(int y = id; y < img_height; y += threadcount)
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{
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int pix = y * img_width;
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// for each pixel, we're going to do the iteration z := z^2 + c where z and c are complex numbers,
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// starting with z = c = complex coord of the pixel. pzi and pzr denote the real and imaginary parts of z.
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// pci and pcr denote the real and imaginary parts of c.
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Packet pzi_start, pci_start;
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for(int i = 0; i < packetSize; i++) pzi_start[i] = pci_start[i] = start.y() + y * step.y();
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for(int x = 0; x < alignedWidth; x += packetSize, pix += packetSize)
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{
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Packet pcr, pci = pci_start, pzr, pzi = pzi_start, pzr_buf;
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for(int i = 0; i < packetSize; i++) pzr[i] = pcr[i] = start.x() + (x+i) * step.x();
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// do the iterations. Every iters_before_test iterations we check for divergence,
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// in which case we can stop iterating.
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int j = 0;
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typedef Eigen::Matrix<int, packetSize, 1> Packeti;
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Packeti pix_iter = Packeti::Zero(), // number of iteration per pixel in the packet
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pix_dont_diverge; // whether or not each pixel has already diverged
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do
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{
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for(int i = 0; i < iters_before_test/4; i++) // peel the inner loop by 4
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{
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# define ITERATE \
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pzr_buf = pzr; \
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pzr = pzr.square(); \
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pzr -= pzi.square(); \
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pzr += pcr; \
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pzi = (2*pzr_buf)*pzi; \
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pzi += pci;
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ITERATE ITERATE ITERATE ITERATE
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}
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pix_dont_diverge = ((pzr.square() + pzi.square())
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.eval() // temporary fix as what follows is not yet vectorized by Eigen
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<= Packet::Constant(4))
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// the 4 here is not a magic value, it's a math fact that if
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// the square modulus is >4 then divergence is inevitable.
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.template cast<int>();
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pix_iter += iters_before_test * pix_dont_diverge;
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j++;
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total_iter += iters_before_test * packetSize;
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}
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while(j < max_iter/iters_before_test && pix_dont_diverge.any()); // any() is not yet vectorized by Eigen
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// compute pixel colors
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for(int i = 0; i < packetSize; i++)
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{
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buffer[4*(pix+i)] = 255*pix_iter[i]/max_iter;
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buffer[4*(pix+i)+1] = 0;
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buffer[4*(pix+i)+2] = 0;
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}
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}
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// if the width is not a multiple of packetSize, fill the remainder in black
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for(int x = alignedWidth; x < img_width; x++, pix++)
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buffer[4*pix] = buffer[4*pix+1] = buffer[4*pix+2] = 0;
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}
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return;
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}
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void MandelbrotThread::run()
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{
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setTerminationEnabled(true);
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double resolution = widget->xradius*2/widget->width();
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max_iter = 128;
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if(resolution < 1e-4f) max_iter += 128 * ( - 4 - std::log10(resolution));
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int img_width = widget->width()/widget->draft;
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int img_height = widget->height()/widget->draft;
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single_precision = resolution > 1e-7f;
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if(single_precision)
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render<float>(img_width, img_height);
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else
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render<double>(img_width, img_height);
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}
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void MandelbrotWidget::paintEvent(QPaintEvent *)
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{
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static float max_speed = 0;
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long long total_iter = 0;
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QTime time;
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time.start();
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for(int th = 0; th < threadcount; th++)
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threads[th]->start(QThread::LowPriority);
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for(int th = 0; th < threadcount; th++)
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{
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threads[th]->wait();
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total_iter += threads[th]->total_iter;
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}
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int elapsed = time.elapsed();
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if(draft == 1)
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{
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float speed = elapsed ? float(total_iter)*1000/elapsed : 0;
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max_speed = std::max(max_speed, speed);
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std::cout << threadcount << " threads, "
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<< elapsed << " ms, "
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<< speed << " iters/s (max " << max_speed << ")" << std::endl;
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int packetSize = threads[0]->single_precision
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? int(Eigen::internal::packet_traits<float>::size)
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: int(Eigen::internal::packet_traits<double>::size);
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setWindowTitle(QString("resolution ")+QString::number(xradius*2/width(), 'e', 2)
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+QString(", %1 iterations per pixel, ").arg(threads[0]->max_iter)
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+(threads[0]->single_precision ? QString("single ") : QString("double "))
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+QString("precision, ")
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+(packetSize==1 ? QString("no vectorization")
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: QString("vectorized (%1 per packet)").arg(packetSize)));
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}
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QImage image(buffer, width()/draft, height()/draft, QImage::Format_RGB32);
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QPainter painter(this);
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painter.drawImage(QPoint(0, 0), image.scaled(width(), height()));
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if(draft>1)
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{
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draft /= 2;
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setWindowTitle(QString("recomputing at 1/%1 resolution...").arg(draft));
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update();
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}
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}
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void MandelbrotWidget::mousePressEvent(QMouseEvent *event)
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{
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if( event->buttons() & Qt::LeftButton )
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{
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lastpos = event->pos();
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double yradius = xradius * height() / width();
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center = Eigen::Vector2d(center.x() + (event->pos().x() - width()/2) * xradius * 2 / width(),
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center.y() + (event->pos().y() - height()/2) * yradius * 2 / height());
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draft = 16;
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for(int th = 0; th < threadcount; th++)
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threads[th]->terminate();
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update();
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}
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}
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void MandelbrotWidget::mouseMoveEvent(QMouseEvent *event)
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{
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QPoint delta = event->pos() - lastpos;
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lastpos = event->pos();
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if( event->buttons() & Qt::LeftButton )
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{
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double t = 1 + 5 * double(delta.y()) / height();
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if(t < 0.5) t = 0.5;
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if(t > 2) t = 2;
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xradius *= t;
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draft = 16;
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for(int th = 0; th < threadcount; th++)
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threads[th]->terminate();
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update();
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}
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}
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int main(int argc, char *argv[])
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{
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QApplication app(argc, argv);
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MandelbrotWidget w;
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w.show();
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return app.exec();
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}
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#include "mandelbrot.moc"
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