/// <summary>
/// Initializes a new instance of the WorldLineConstraint.
/// </summary>
/// <param name="body">The body of the constraint.</param>
/// <param name="localAnchor">The anchor point on the body in local (body)
/// coordinates.</param>
/// <param name="lineDirection">The axis defining the line in world space.</param>/param>
public PointOnLine(RigidBody body, JVector localAnchor, JVector lineDirection)
: base(body, null)
{
if (lineDirection.LengthSquared() == 0.0f)
throw new ArgumentException("Line direction can't be zero", "lineDirection");
localAnchor1 = localAnchor;
this.anchor = body.position + JVector.Transform(localAnchor, body.orientation);
this.lineNormal = lineDirection;
this.lineNormal.Normalize();
}
public static bool ClosestPoints(ISupportMappable support1, ISupportMappable support2, ref JMatrix orientation1,
ref JMatrix orientation2, ref JVector position1, ref JVector position2,
out JVector p1, out JVector p2, out JVector normal)
{
VoronoiSimplexSolver simplexSolver = simplexSolverPool.GetNew();
simplexSolver.Reset();
p1 = p2 = JVector.Zero;
JVector r = position1 - position2;
JVector w, v;
JVector supVertexA;
JVector rn,vn;
rn = JVector.Negate(r);
SupportMapTransformed(support1, ref orientation1, ref position1, ref rn, out supVertexA);
JVector supVertexB;
SupportMapTransformed(support2, ref orientation2, ref position2, ref r, out supVertexB);
v = supVertexA - supVertexB;
normal = JVector.Zero;
int maxIter = 15;
float distSq = v.LengthSquared();
float epsilon = 0.00001f;
while ((distSq > epsilon) && (maxIter-- != 0))
{
vn = JVector.Negate(v);
SupportMapTransformed(support1, ref orientation1, ref position1, ref vn, out supVertexA);
SupportMapTransformed(support2, ref orientation2, ref position2, ref v, out supVertexB);
w = supVertexA - supVertexB;
if (!simplexSolver.InSimplex(w)) simplexSolver.AddVertex(w, supVertexA, supVertexB);
if (simplexSolver.Closest(out v))
{
distSq = v.LengthSquared();
normal = v;
}
else distSq = 0.0f;
}
simplexSolver.ComputePoints(out p1, out p2);
if (normal.LengthSquared() > JMath.Epsilon * JMath.Epsilon)
normal.Normalize();
simplexSolverPool.GiveBack(simplexSolver);
return true;
}
// see: btSubSimplexConvexCast.cpp
/// <summary>
/// Checks if a ray definied through it's origin and direction collides
/// with a shape.
/// </summary>
/// <param name="support">The supportmap implementation representing the shape.</param>
/// <param name="orientation">The orientation of the shape.</param>
/// <param name="invOrientation">The inverse orientation of the shape.</param>
/// <param name="position">The position of the shape.</param>
/// <param name="origin">The origin of the ray.</param>
/// <param name="direction">The direction of the ray.</param>
/// <param name="fraction">The fraction which gives information where at the
/// ray the collision occured. The hitPoint is calculated by: origin+friction*direction.</param>
/// <param name="normal">The normal from the ray collision.</param>
/// <returns>Returns true if the ray hit the shape, false otherwise.</returns>
public static bool Raycast(ISupportMappable support, ref JMatrix orientation, ref JMatrix invOrientation,
ref JVector position,ref JVector origin,ref JVector direction, out float fraction, out JVector normal)
{
VoronoiSimplexSolver simplexSolver = simplexSolverPool.GetNew();
simplexSolver.Reset();
normal = JVector.Zero;
fraction = float.MaxValue;
float lambda = 0.0f;
JVector r = direction;
JVector x = origin;
JVector w, p, v;
JVector arbitraryPoint;
SupportMapTransformed(support, ref orientation, ref position, ref r, out arbitraryPoint);
JVector.Subtract(ref x, ref arbitraryPoint, out v);
int maxIter = MaxIterations;
float distSq = v.LengthSquared();
float epsilon = 0.000001f;
float VdotR;
while ((distSq > epsilon) && (maxIter-- != 0))
{
SupportMapTransformed(support, ref orientation, ref position, ref v, out p);
JVector.Subtract(ref x, ref p, out w);
float VdotW = JVector.Dot(ref v, ref w);
if (VdotW > 0.0f)
{
VdotR = JVector.Dot(ref v, ref r);
if (VdotR >= -JMath.Epsilon)
{
simplexSolverPool.GiveBack(simplexSolver);
return false;
}
else
{
lambda = lambda - VdotW / VdotR;
JVector.Multiply(ref r, lambda, out x);
JVector.Add(ref origin, ref x, out x);
JVector.Subtract(ref x, ref p, out w);
normal = v;
}
}
if (!simplexSolver.InSimplex(w)) simplexSolver.AddVertex(w, x, p);
if (simplexSolver.Closest(out v)) { distSq = v.LengthSquared(); }
else distSq = 0.0f;
}
#region Retrieving hitPoint
// Giving back the fraction like this *should* work
// but is inaccurate against large objects:
// fraction = lambda;
JVector p1, p2;
simplexSolver.ComputePoints(out p1, out p2);
p2 = p2 - origin;
fraction = p2.Length() / direction.Length();
#endregion
if (normal.LengthSquared() > JMath.Epsilon * JMath.Epsilon)
normal.Normalize();
simplexSolverPool.GiveBack(simplexSolver);
return true;
}