Mandelbrot Example

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#include "renderthread.h" #include <QImage> #include <cmath> RenderThread::RenderThread(QObject *parent) : QThread(parent) { restart = false; abort = false; for (int i = 0; i < ColormapSize; ++i) colormap[i] = rgbFromWaveLength(380.0 + (i * 400.0 / ColormapSize)); } RenderThread::~RenderThread() { mutex.lock(); abort = true; condition.wakeOne(); mutex.unlock(); wait(); } void RenderThread::render(double centerX, double centerY, double scaleFactor, QSize resultSize) { QMutexLocker locker(&mutex); this->centerX = centerX; this->centerY = centerY; this->scaleFactor = scaleFactor; this->resultSize = resultSize; if (!isRunning()) { start(LowPriority); } else { restart = true; condition.wakeOne(); } } void RenderThread::run() { forever { mutex.lock(); QSize resultSize = this->resultSize; double scaleFactor = this->scaleFactor; double centerX = this->centerX; double centerY = this->centerY; mutex.unlock(); int halfWidth = resultSize.width() / 2; int halfHeight = resultSize.height() / 2; QImage image(resultSize, QImage::Format_RGB32); const int NumPasses = 8; int pass = 0; while (pass < NumPasses) { const int MaxIterations = (1 << (2 * pass + 6)) + 32; const int Limit = 4; bool allBlack = true; for (int y = -halfHeight; y < halfHeight; ++y) { if (restart) break; if (abort) return; uint *scanLine = reinterpret_cast<uint *>(image.scanLine(y + halfHeight)); double ay = centerY + (y * scaleFactor); for (int x = -halfWidth; x < halfWidth; ++x) { double ax = centerX + (x * scaleFactor); double a1 = ax; double b1 = ay; int numIterations = 0; do { ++numIterations; double a2 = (a1 * a1) - (b1 * b1) + ax; double b2 = (2 * a1 * b1) + ay; if ((a2 * a2) + (b2 * b2) > Limit) break; ++numIterations; a1 = (a2 * a2) - (b2 * b2) + ax; b1 = (2 * a2 * b2) + ay; if ((a1 * a1) + (b1 * b1) > Limit) break; } while (numIterations < MaxIterations); if (numIterations < MaxIterations) { *scanLine++ = colormap[numIterations % ColormapSize]; allBlack = false; } else { *scanLine++ = qRgb(0, 0, 0); } } } if (allBlack && pass == 0) { pass = 4; } else { if (!restart) emit renderedImage(image, scaleFactor); ++pass; } } mutex.lock(); if (!restart) condition.wait(&mutex); restart = false; mutex.unlock(); } } uint RenderThread::rgbFromWaveLength(double wave) { double r = 0.0; double g = 0.0; double b = 0.0; if (wave >= 380.0 && wave <= 440.0) { r = -1.0 * (wave - 440.0) / (440.0 - 380.0); b = 1.0; } else if (wave >= 440.0 && wave <= 490.0) { g = (wave - 440.0) / (490.0 - 440.0); b = 1.0; } else if (wave >= 490.0 && wave <= 510.0) { g = 1.0; b = -1.0 * (wave - 510.0) / (510.0 - 490.0); } else if (wave >= 510.0 && wave <= 580.0) { r = (wave - 510.0) / (580.0 - 510.0); g = 1.0; } else if (wave >= 580.0 && wave <= 645.0) { r = 1.0; g = -1.0 * (wave - 645.0) / (645.0 - 580.0); } else if (wave >= 645.0 && wave <= 780.0) { r = 1.0; } double s = 1.0; if (wave > 700.0) s = 0.3 + 0.7 * (780.0 - wave) / (780.0 - 700.0); else if (wave < 420.0) s = 0.3 + 0.7 * (wave - 380.0) / (420.0 - 380.0); r = std::pow(r * s, 0.8); g = std::pow(g * s, 0.8); b = std::pow(b * s, 0.8); return qRgb(int(r * 255), int(g * 255), int(b * 255)); }