// ----------------------------------------------------------------------------
// Returns the distance between a point and a line. The line is defined in
// terms of a point on the line ("lineOrigin") and a UNIT vector parallel to
// the line ("lineUnitTangent")
public static float DistanceFromLine(Vec3 point, Vec3 lineOrigin, Vec3 lineUnitTangent)
{
Vec3 offset = point - lineOrigin;
Vec3 perp = offset.PerpendicularComponent(lineUnitTangent);
return(perp.Length());
}
// Returns a position randomly distributed inside a sphere of unit radius
// centered at the origin. Orientation will be random and length will range
// between 0 and 1
public static Vec3 RandomVectorInUnitRadiusSphere()
{
Vec3 v = new Vec3();
do
{
v.Set((Utilities.Random() * 2) - 1, (Utilities.Random() * 2) - 1, (Utilities.Random() * 2) - 1);
}while (v.Length() >= 1);
return(v);
}
// ----------------------------------------------------------------------------
// used by limitMaxDeviationAngle / limitMinDeviationAngle below
public static Vec3 LimitDeviationAngleUtility(bool insideOrOutside, Vec3 source, float cosineOfConeAngle, Vec3 basis)
{
// immediately return zero length input vectors
float sourceLength = source.Length();
if (sourceLength == 0)
{
return(source);
}
// measure the angular diviation of "source" from "basis"
Vec3 direction = source / sourceLength;
float cosineOfSourceAngle = direction.Dot(basis);
// Simply return "source" if it already meets the angle criteria.
// (note: we hope this top "if" gets compiled out since the flag
// is a constant when the function is inlined into its caller)
if (insideOrOutside)
{
// source vector is already inside the cone, just return it
if (cosineOfSourceAngle >= cosineOfConeAngle)
{
return(source);
}
}
else
{
// source vector is already outside the cone, just return it
if (cosineOfSourceAngle <= cosineOfConeAngle)
{
return(source);
}
}
// find the portion of "source" that is perpendicular to "basis"
Vec3 perp = source.PerpendicularComponent(basis);
// normalize that perpendicular
Vec3 unitPerp = perp.Normalize();
// construct a new vector whose length equals the source vector,
// and lies on the intersection of a plane (formed the source and
// basis vectors) and a cone (whose axis is "basis" and whose
// angle corresponds to cosineOfConeAngle)
float perpDist = (float)Math.Sqrt(1 - (cosineOfConeAngle * cosineOfConeAngle));
Vec3 c0 = basis * cosineOfConeAngle;
Vec3 c1 = unitPerp * perpDist;
return((c0 + c1) * sourceLength);
}
// if this position is outside sphere, push it back in by one diameter
public Vec3 SphericalWraparound(Vec3 center, float radius)
{
Vec3 offset = this - center;
float r = offset.Length();
if (r > radius)
{
return(this + ((offset / r) * radius * -2));
}
else
{
return(this);
}
}
// ----------------------------------------------------------------------------
// Returns a position randomly distributed on a disk of unit radius
// on the XZ (Y=0) plane, centered at the origin. Orientation will be
// random and length will range between 0 and 1
public static Vec3 RandomVectorOnUnitRadiusXZDisk()
{
Vec3 v = new Vec3();
do
{
v.Set((Utilities.Random() * 2) - 1, 0, (Utilities.Random() * 2) - 1);
}
while (v.Length() >= 1);
return v;
}
// ----------------------------------------------------------------------------
// used by limitMaxDeviationAngle / limitMinDeviationAngle below
public static Vec3 LimitDeviationAngleUtility(bool insideOrOutside, Vec3 source, float cosineOfConeAngle, Vec3 basis)
{
// immediately return zero length input vectors
float sourceLength = source.Length();
if (sourceLength == 0) return source;
// measure the angular diviation of "source" from "basis"
Vec3 direction = source / sourceLength;
float cosineOfSourceAngle = direction.Dot(basis);
// Simply return "source" if it already meets the angle criteria.
// (note: we hope this top "if" gets compiled out since the flag
// is a constant when the function is inlined into its caller)
if (insideOrOutside)
{
// source vector is already inside the cone, just return it
if (cosineOfSourceAngle >= cosineOfConeAngle) return source;
}
else
{
// source vector is already outside the cone, just return it
if (cosineOfSourceAngle <= cosineOfConeAngle) return source;
}
// find the portion of "source" that is perpendicular to "basis"
Vec3 perp = source.PerpendicularComponent(basis);
// normalize that perpendicular
Vec3 unitPerp = perp.Normalize();
// construct a new vector whose length equals the source vector,
// and lies on the intersection of a plane (formed the source and
// basis vectors) and a cone (whose axis is "basis" and whose
// angle corresponds to cosineOfConeAngle)
float perpDist = (float)Math.Sqrt(1 - (cosineOfConeAngle * cosineOfConeAngle));
Vec3 c0 = basis * cosineOfConeAngle;
Vec3 c1 = unitPerp * perpDist;
return (c0 + c1) * sourceLength;
}
