/** Compute forces and update particles **/
void ParticleSystem::computeForcesAndUpdateParticles(float t)
{
time = t;
if (!simulate) return;
for (int i = 0; i < 20; i++)
{
for (int j = 19; j >= 0; j--)
{
if (i == 0 && (j == 0 || j == 19)) continue;
Vec3f force = Vec3f(g);
Vec3f position = particles[i][j].getPosition();
force += springForce(i - 1, j, position);
force += springForce(i + 1, j, position);
force += springForce(i, j - 1, position);
force += springForce(i, j + 1, position);
if (force.length() > 10)
{
force.normalize();
force *= 10;
}
particles[i][j].applyForce(force);
}
}
for (int i = 0; i < 20; i++)
for (int j = 19; j >= 0; j--)
particles[i][j].move(t);
bakeParticles(t);
}
void ForestWindAccumulator::updateWind( const VectorF &windForce, F32 timeDelta )
{
PROFILE_SCOPE( ForestWindAccumulator_UpdateWind );
// Update values from datablock... this way we can
// change settings live and see instant results.
const F32 tightnessCoefficient = mDataBlock->mTightnessCoefficient;
const F32 dampingCoefficient = mDataBlock->mDampingCoefficient;
const F32 mass = mDataBlock->mMass * mScale;
const F32 rigidity = mDataBlock->mRigidity * mScale;
// This will be the accumulated
// target strength for flutter.
//F32 targetStrength = windForce.len();
// This will be the accumulated
// target displacement vector.
Point2F target( windForce.x, windForce.y );
// This particle is the spring target.
// It has a mass of 0, which we count as
// an infinite mass.
mParticles[0].position = target;
Point2F relVel = target * timeDelta;
Point2F diff( 0, 0 );
Point2F springForce( 0, 0 );
// Spring length is the target
// particle's position minus the
// current displacement/direction vector.
diff = mParticles[0].position - mCurrentDir;
// F = diff * tightness - v * -damping
diff *= tightnessCoefficient;
springForce = diff - ( (mParticles[1].position - mParticles[1].lastPosition) * -dampingCoefficient );
Point2F accel( 0, 0 );
accel = springForce * (rigidity * 0.001f) / (mass * 0.001f);
_updateParticle( &mParticles[1], accel, timeDelta );
mCurrentDir *= 0.989f;
mCurrentDir += mParticles[1].position;
mCurrentStrength += windForce.len() * timeDelta;
mCurrentStrength *= 0.98f;
}
void SimSuspUpdate(tSuspension *susp)
{
susp->force = (springForce(susp) + damperForce(susp)) * susp->spring.bellcrank;
}
