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 loop() {
for (int i = 0; i < particles.length; i++) {
/* check if particle is active.
* if so, animate the particle, if not, reset the particle
* to a random start position */
if (particles[i].isActive) {
Vector3f myDirection = new Vector3f(event().mouseX, event().mouseY, 0);
myDirection.sub(particles[i].position);
final float myDistance = myDirection.length();
myDirection.scale(particles[i].speed / myDistance);
particles[i].position.add(myDirection);
particles[i].color.a = 1 - myDistance / (-1.5f * SPAWN_DEPTH);
if (myDistance < 1) {
particles[i].isActive = false;
}
} else {
particles[i].isActive = true;
particles[i].position.set(
_myRandom.getFloat(-640, 640), _myRandom.getFloat(-480, 480), SPAWN_DEPTH);
particles[i].color.a = 0;
}
/* map position to backup array */
positionbackuparray[i * 3 + 0] = particles[i].position.x;
positionbackuparray[i * 3 + 1] = particles[i].position.y;
positionbackuparray[i * 3 + 2] = particles[i].position.z;
/* map color4f to backup array */
colorbackuparray[i * 4 + 0] = particles[i].color.r;
colorbackuparray[i * 4 + 1] = particles[i].color.g;
colorbackuparray[i * 4 + 2] = particles[i].color.b;
colorbackuparray[i * 4 + 3] = particles[i].color.a;
}
}
