/// <summary>
/// Finds a least penetrating vector.
/// </summary>
/// <param name="axis">The axis.</param>
/// <param name="other">The other.</param>
/// <param name="penetrationNormal">The penetration normal.</param>
/// <param name="penetrationLength">Length of the penetration.</param>
/// <returns>
/// True, if a least penetrating vector could be found (no Axis separates the bounding volumes).
/// </returns>
private bool FindLeastPenetrating(Vector2 axis, BoundingVolume other, ref Vector2 penetrationNormal, ref float penetrationLength)
{
float minThis, maxThis, minOther, maxOther;
// Tests if separating axis exists
if (TestSeparatingAxis(axis, other, out minThis, out maxThis, out minOther, out maxOther))
{
return(false);
}
// Find least penetrating axis
float diff = Math.Min(maxOther, maxThis) - Math.Max(minOther, minThis);
// Store penetration vector
if (diff < penetrationLength)
{
penetrationLength = diff;
penetrationNormal = axis;
}
return(true);
}
/// <summary>
/// Initializes a new instance of the <see cref="FluidParticle"/> class.
/// </summary>
public FluidParticle()
{
this.Life = 0;
this.Mass = 1.0f;
this.Position = Vector2.Zero;
this.PositionOld = this.Position;
this.Velocity = Vector2.Zero;
this.Force = Vector2.Zero;
this.Density = Constants.DENSITY_OFFSET;
// update (integrate) using basic verlet with small drag
this.Solver = new Verlet
{
Damping = 0.01f
};
this.BoundingVolume = new PointVolume
{
Position = this.Position,
Margin = Constants.CELL_SPACE * 0.25f,
};
this.UpdatePressure();
}
/// <summary>
/// Tests if this bounding volume intersects the other bounding volume,
/// using the "Separating Axis Test" (SAT).
/// </summary>
/// <param name="other">The bounding volume to test against</param>
/// <param name="penetrationNormal">The penetration vector (direction of the least penetration).</param>
/// <param name="penetrationLength">Length of the penetration.</param>
/// <returns>
/// True, if the both bounding volumes intersect.
/// </returns>
public bool Intersects(BoundingVolume other, out Vector2 penetrationNormal, out float penetrationLength)
{
penetrationNormal = Vector2.Zero;
penetrationLength = float.MaxValue;
// Axis of this
if (this.Axis != null)
{
foreach (var axis in this.Axis)
{
if (!FindLeastPenetrating(axis, other, ref penetrationNormal, ref penetrationLength))
{
return(false);
}
}
}
// Axis of other
if (other.Axis != null)
{
foreach (var axis in other.Axis)
{
if (!FindLeastPenetrating(axis, other, ref penetrationNormal, ref penetrationLength))
{
return(false);
}
}
}
// Flip penetrationDirection to point away from this
if (Vector2.Dot(other.Position - this.Position, penetrationNormal) > 0.0f)
{
Vector2.Mult(ref penetrationNormal, -1.0f, out penetrationNormal);
}
return(true);
}