diff --git a/src/osgParticle/FluidProgram.cpp b/src/osgParticle/FluidProgram.cpp index b3767f7ca..5465360ab 100644 --- a/src/osgParticle/FluidProgram.cpp +++ b/src/osgParticle/FluidProgram.cpp @@ -32,16 +32,25 @@ void osgParticle::FluidProgram::execute(double dt) float Volume = Area*radius*four_over_three; // compute force due to gravity + boyancy of displacing the fluid that the particle is emersed in. - osg::Vec3 force = _acceleration * (particle->getMass() - _density*Volume); - + osg::Vec3 accel_gravity = _acceleration * ((particle->getMass() - _density*Volume) * particle->getMassInv()); + // compute force due to friction + osg::Vec3 velBefore = particle->getVelocity(); osg::Vec3 relative_wind = particle->getVelocity()-_wind; - force -= relative_wind * Area * (_viscosityCoefficient + _densityCoefficeint*relative_wind.length()); + osg::Vec3 wind_force = - relative_wind * Area * (_viscosityCoefficient + _densityCoefficeint*relative_wind.length()); + osg::Vec3 wind_accel = wind_force * particle->getMassInv(); + + double critical_dt2 = relative_wind.length2()/wind_accel.length2(); + double compenstated_dt = dt; + if (critical_dt2 < dt*dt) + { + // osg::notify(osg::NOTICE)<<"** Could be critical: dt="<