SimulatorThread.cpp

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#include "SimulatorThread.h"
#include "ThyrixApplication.h"
#include "ThyrixMainFrame.h"
#include "World.h"

SimulatorThread::SimulatorThread(ThyrixMainFrame *iniFrame) :
   wxThread(wxTHREAD_JOINABLE),
   frame(iniFrame),
   timeFactor(1000),
   paused(false),
   expectedTime(0){        
   setTimeFactor(1);
   setFramesPerSecond(30);
}

SimulatorThread::~SimulatorThread(){
}

void SimulatorThread::step() {
      //this is called directly by the parent frame, following a command
    //needs mutex sincronization with the thread.
    world->advanceTime();
}

void SimulatorThread::setPause() {
    paused = true;
}

void SimulatorThread::setTimeFactor(float newFactor) {
    timeFactor = newFactor;
    paused = false;
    expectedTime = 0;
    simulationTimer.Start();
}

void SimulatorThread::setFramesPerSecond(int fps) {
    frameInterval = 1000 / fps;
}

void SimulatorThread::sleepIfAhead() {
   
    //sleep when more than 5ms ahead
    static const int kSleepThreshold = 5;

    unsigned expectedTimeMs = (unsigned)(expectedTime * 1000);
    unsigned realMs = (unsigned)simulationTimer.Time();
    int aheadMs = 0;
    if ( expectedTimeMs > realMs) {
        aheadMs = expectedTimeMs - realMs;
    }
    if (aheadMs > kSleepThreshold) {
        Sleep(aheadMs);
    }
    //to avoid timer overflow, reset it once in a while
    if (realMs > 100000) {
        setTimeFactor(timeFactor);
    }
}

void* SimulatorThread::Entry(){
   wxStopWatch displayTimer;
   simulationTimer.Start(); //starts the timing of the running time of the simulator
   while(!TestDestroy()){
      displayTimer.Start(); //starts the timing of the duration of a frame   
      frame->paint(); //draws the image
      if (paused) {
         Sleep(frameInterval);
      } else {

         //advance simulator time, in a loop, as long a refresh of the display is not needed
         do {
            
            //wait if the simulation should not advance yet
            sleepIfAhead();

            //advance simulator time
            world->advanceTime();
            
            //computes the real time at which the next simulator timestep should be executed,
            //given the desired acceleration factor between real time and simulator time
            expectedTime += world->getDt() / timeFactor;

         } while (displayTimer.Time() < frameInterval);

      }
   }
   return NULL;
}

void SimulatorThread::OnExit(){
}

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