public void pre_step() {
Vector3f ab = mathematik.Util.sub(mParticleA.position(), mParticleB.position());
Vector3f cb = mathematik.Util.sub(mParticleC.position(), mParticleB.position());
final float mCurrentAngle = ab.angle(cb);
if (mCurrentAngle < mMinAngle) {
final int TINY_FACTOR_MODELL = 0;
final int TRIG_MODELL = 1;
final int MAX_DISTANCE_MODELL = 2;
final int mModell = TRIG_MODELL;
switch (mModell) {
case TINY_FACTOR_MODELL:
{
final float TINY_FACTOR = 1.1f;
final float mDistance =
mParticleA.position().distance(mParticleC.position()) * TINY_FACTOR;
restlength(mDistance);
}
break;
case TRIG_MODELL:
{
// a = sqrt ( b*b + c*c - 2bc*cosA )
final float b = ab.length();
final float c = cb.length();
final float mDistance =
(float) Math.sqrt(b * b + c * c - 2 * b * c * (float) Math.cos(mMinAngle));
restlength(mDistance);
}
break;
case MAX_DISTANCE_MODELL:
{
final float mDistance =
mParticleA.position().distance(mParticleB.position())
+ mParticleC.position().distance(mParticleB.position());
restlength(mDistance);
}
break;
}
active(true);
}
}
public void setRestLengthByPosition() {
mRestLength = mA.position().distance(mB.position());
}
public Spring(
Particle theA, Particle theB, final float theSpringConstant, final float theSpringDamping) {
this(
theA, theB, theSpringConstant, theSpringDamping, theA.position().distance(theB.position()));
}
public Spring(Particle theA, Particle theB) {
this(theA, theB, 2.0f, 0.1f, theA.position().distance(theB.position()));
}
public boolean dead() {
return mA.dead() || mB.dead();
}
public void apply(final float theDeltaTime, final Physics theParticleSystem) {
// if (!mA.fixed() || !mB.fixed()) {
float a2bX = mA.position().x - mB.position().x;
float a2bY = mA.position().y - mB.position().y;
float a2bZ = mA.position().z - mB.position().z;
final float myInversDistance = fastInverseSqrt(a2bX * a2bX + a2bY * a2bY + a2bZ * a2bZ);
final float myDistance = 1.0F / myInversDistance;
if (myDistance == 0.0F) {
a2bX = 0.0F;
a2bY = 0.0F;
a2bZ = 0.0F;
} else {
a2bX *= myInversDistance;
a2bY *= myInversDistance;
a2bZ *= myInversDistance;
}
final float mSpringForce = -(myDistance - mRestLength) * mSpringConstant;
final float Va2bX = mA.velocity().x - mB.velocity().x;
final float Va2bY = mA.velocity().y - mB.velocity().y;
final float Va2bZ = mA.velocity().z - mB.velocity().z;
final float mDampingForce = -mSpringDamping * (a2bX * Va2bX + a2bY * Va2bY + a2bZ * Va2bZ);
final float r = mSpringForce + mDampingForce;
a2bX *= r;
a2bY *= r;
a2bZ *= r;
if (mOneWay) {
if (!mB.fixed()) {
mB.force().add(-2 * a2bX, -2 * a2bY, -2 * a2bZ);
}
} else {
if (!mA.fixed()) {
mA.force().add(a2bX, a2bY, a2bZ);
}
if (!mB.fixed()) {
mB.force().add(-a2bX, -a2bY, -a2bZ);
}
}
// }
}
public final float currentLength() {
return mA.position().distance(mB.position());
}