void EnumerateMagnets()
{
numMagnets = 0;
if (Parent == null)
{
return;
}
foreach (Node node in Parent.Nodes)
{
ParticlesMagnet magnet = node as ParticlesMagnet;
if (magnet != null)
{
if (numMagnets >= MaxMagnets)
{
break;
}
Matrix32 transform = magnet.CalcLocalToParentTransform();
Widget basicWidget = GetBasicWidget();
if (basicWidget != null)
{
for (Node n = Parent; n != basicWidget; n = n.Parent)
{
if (n.AsWidget != null)
{
transform *= n.AsWidget.CalcLocalToParentTransform();
}
}
}
magnets[numMagnets++] = new MagnetData {
Magnet = magnet,
PrecalcTransitionMatrix = transform.CalcInversed(),
PrecalcInvTransitionMatrix = transform
};
}
}
}
void ApplyMagnetToParticle(Particle p, MagnetData magnetData, float delta)
{
ParticlesMagnet magnet = magnetData.Magnet;
Vector2 targetPosition = p.RegularPosition;
targetPosition = magnetData.PrecalcTransitionMatrix.TransformVector(targetPosition);
switch (magnet.Shape)
{
case EmitterShape.Area:
// Looking for point of magnet's edge, in the direction of particle is moving.
if (targetPosition.X > 0 && targetPosition.X < magnet.Size.X &&
targetPosition.X > 0 && targetPosition.Y < magnet.Size.Y)
{
// Particle is got inside magnet, move it outside.
float d0 = targetPosition.X;
float d1 = targetPosition.Y;
float d2 = magnet.Size.X - targetPosition.X;
float d3 = magnet.Size.Y - targetPosition.Y;
if (d0 < d1 && d0 < d2 && d0 < d3)
{
targetPosition.X = 0;
}
else if (d1 < d0 && d1 < d2 && d1 < d3)
{
targetPosition.Y = 0;
}
else if (d2 < d0 && d2 < d1 && d2 < d3)
{
targetPosition.X = magnet.Size.X;
}
else
{
targetPosition.Y = magnet.Size.Y;
}
}
else
{
targetPosition.X = Mathf.Clamp(targetPosition.X, 0, magnet.Size.X);
targetPosition.Y = Mathf.Clamp(targetPosition.Y, 0, magnet.Size.Y);
}
break;
case EmitterShape.Ellipse:
if (Math.Abs(magnet.Size.Y) > 1e-5)
{
Vector2 center = 0.5f * magnet.Size;
float k = magnet.Size.X / magnet.Size.Y;
targetPosition -= center;
targetPosition.Y *= k;
targetPosition = targetPosition.Normalized;
targetPosition *= magnet.Size.X * 0.5f;
targetPosition.Y /= k;
targetPosition += center;
}
else
{
targetPosition = 0.5f * magnet.Size;
}
break;
case EmitterShape.Line:
targetPosition.Y = 0.5f * magnet.Size.Y;
if (targetPosition.X < 0.0f)
{
targetPosition.X = 0.0f;
}
else if (targetPosition.X > magnet.Size.X)
{
targetPosition.X = magnet.Size.X;
}
break;
case EmitterShape.Point:
targetPosition = 0.5f * magnet.Size;
break;
}
targetPosition = magnetData.PrecalcInvTransitionMatrix.TransformVector(targetPosition);
Vector2 direction = targetPosition - p.RegularPosition;
float squaredDistance = direction.SqrLength;
direction = direction.Normalized;
float magnetStrength = magnet.Strength;
if (magnet.Attenuation > 0.0001f)
{
magnetStrength /= (float)Math.Pow(squaredDistance, magnet.Attenuation * 0.5f);
}
float t = magnetStrength * p.MagnetAmountCurrent * delta;
if (t * t > squaredDistance)
{
t = (float)Math.Sqrt(squaredDistance);
}
p.RegularPosition += direction * t;
}