internal BoundingBoxData(Vector3 startDir, Vector3 yDir, Edge rotatorEdge, Vector3 rotatorVector,
TVGLConvexHull convexHull)
{
Direction = startDir;
PosYDir = yDir;
RotatorEdge = rotatorEdge;
RotatorVector = rotatorVector;
OrthGaussSphereArcs = new List <GaussSphereArc>();
// make arrays of the Dots with start and end directions (x-values) to help subsequent
// foreach loop which will look up faces multiple times.
var startingDots = new double[convexHull.Faces.Length];
for (var i = 0; i < convexHull.Faces.Length; i++)
{
var face = convexHull.Faces[i];
face.IndexInList = i;
startingDots[i] = face.Normal.Dot(startDir);
}
foreach (var edge in convexHull.Edges)
{
var ownedX = startingDots[edge.OwnedFace.IndexInList];
var otherX = startingDots[edge.OtherFace.IndexInList];
if (otherX * ownedX <= 0)
{
var ownedY = edge.OwnedFace.Normal.Dot(yDir);
var otherY = edge.OtherFace.Normal.Dot(yDir);
//if ((ownedX < 0 && ownedY > 0) || (ownedX > 0 && ownedY < 0))
// OrthGaussSphereArcs.Add(new GaussSphereArc(edge, edge.OwnedFace));
//else if ((otherX < 0 && otherY > 0) || (otherX > 0 && otherY < 0))
// OrthGaussSphereArcs.Add(new GaussSphereArc(edge, edge.OtherFace));
if ((ownedX <= 0 && ownedY > 0) || (ownedX >= 0 && ownedY < 0))
{
OrthGaussSphereArcs.Add(new GaussSphereArc(edge, edge.OwnedFace));
}
else if ((otherX <= 0 && otherY > 0) || (otherX >= 0 && otherY < 0))
{
OrthGaussSphereArcs.Add(new GaussSphereArc(edge, edge.OtherFace));
}
}
}
OrthVertices =
OrthGaussSphereArcs.SelectMany(arc => new[] { arc.Edge.From, arc.Edge.To }).Distinct().ToList();
var maxDistance = double.NegativeInfinity;
foreach (var v in convexHull.Vertices)
{
var distance = rotatorEdge.From.Coordinates.Subtract(v.Coordinates).Dot(startDir);
if (distance > maxDistance)
{
maxDistance = distance;
BackVertex = v;
}
}
}
/// <summary>
/// The MC_ApproachOne rotates around each edge of the convex hull between the owned and
/// other faces. In this way, it guarantees a much more optimal solution than the flat
/// with face algorithm, but is, therefore, slower.
/// </summary>
/// <timeDomain>
/// Since the computation cost for each Bounding Box is linear O(n),
/// and the approximate worse case number of normals considered is n*PI/maxDeltaAngle,
/// Lower Bound O(n^2). Upper Bound O(n^(2)*PI/maxDeltaAngle). [ex. upper bound is O(36*n^2) when MaxDeltaAngle = 5
/// degrees.]
/// </timeDomain>
/// <accuracy>
/// Garantees the optimial orientation is within maxDeltaAngle error.
/// </accuracy>
private static BoundingBox OrientedBoundingBox(TVGLConvexHull convexHull)
{
var minBox = new BoundingBox(
new Vector3(double.PositiveInfinity, double.PositiveInfinity, double.PositiveInfinity),
new[] { Vector3.UnitX, Vector3.UnitY, Vector3.UnitZ },
new Vector3(double.NegativeInfinity, double.NegativeInfinity, double.NegativeInfinity));
foreach (var rotateEdge in convexHull.Edges)
{
#region Initialize variables
//Initialize variables
//rotatorVector is basically the edge in question - the vector that is being rotated about
var rotatorVector = rotateEdge.Vector.Normalize();
// startDir is the starting Direction - based on the OtherFace
var startDir = rotateEdge.OtherFace.Normal;
// endDir is the OwnedFace final Direction - we go from Other to Owned since in order to be about
// the positive Direction of the rotatorVector
var endDir = rotateEdge.OwnedFace.Normal;
// posYDir is the vector for the positive y-Direction. Well, this is a simplification of the
//gauss sphere to a 2D circle. The Direction (such as startDir) represents the x-axis and this
//, which is the orthogonal is the y Direction
var origPosYDir = rotatorVector.Cross(startDir).Normalize();
var totalAngle = Math.PI - rotateEdge.InternalAngle;
var thisBoxData = new BoundingBoxData(startDir, origPosYDir, rotateEdge, rotatorVector, convexHull);
#endregion
FindOBBAlongDirection(thisBoxData);
if (thisBoxData.Box.Volume < minBox.Volume)
{
minBox = thisBoxData.Box;
}
var angle = 0.0;
var deltaAngleToBackChange = 0.0;
var deltaAngleOrthSet = 0.0;
BoundingBoxData backChangeBox = null;
BoundingBoxData sideChangeBox = null;
do
{
if (deltaAngleToBackChange <= 0)
{
backChangeBox = thisBoxData.Copy();
deltaAngleToBackChange = UpdateBackAngle(backChangeBox);
}
if (deltaAngleOrthSet <= 0)
{
sideChangeBox = thisBoxData.Copy();
deltaAngleOrthSet = UpdateOrthAngle(sideChangeBox);
}
BoundingBoxData nextBoxData;
if (deltaAngleOrthSet < deltaAngleToBackChange)
{
deltaAngleToBackChange -= deltaAngleOrthSet;
angle += deltaAngleOrthSet;
deltaAngleOrthSet = 0;
nextBoxData = sideChangeBox;
}
else if (deltaAngleToBackChange < deltaAngleOrthSet)
{
deltaAngleOrthSet -= deltaAngleToBackChange;
angle += deltaAngleToBackChange;
deltaAngleToBackChange = 0;
nextBoxData = backChangeBox;
}
else // if they are equal to each other
{
angle += deltaAngleToBackChange;
deltaAngleOrthSet = deltaAngleToBackChange = 0;
nextBoxData = backChangeBox;
}
if (angle > totalAngle)
{
// nextBoxData = new BoundingBoxData(endDir, rotatorVector.Cross(endDir).Normalize(), rotateEdge, rotatorVector, convexHull);
nextBoxData.Angle = totalAngle;
nextBoxData.Direction = endDir;
}
else
{
nextBoxData.Angle = angle;
nextBoxData.Direction = UpdateDirection(startDir, rotatorVector, origPosYDir, angle);
}
nextBoxData.PosYDir = nextBoxData.RotatorVector.Cross(nextBoxData.Direction).Normalize();
/****************/
FindOBBAlongDirection(nextBoxData);
/****************/
if (DifferentMembershipInExtrema(thisBoxData, nextBoxData))
{
var lowerBox = thisBoxData;
var upperBox = nextBoxData;
var midBox = thisBoxData.Copy();
while (!lowerBox.Angle.IsPracticallySame(upperBox.Angle, Constants.OBBTolerance))
{
midBox.Direction = (lowerBox.Direction + upperBox.Direction).Divide(2).Normalize();
midBox.Angle = (lowerBox.Angle + upperBox.Angle) / 2.0;
FindOBBAlongDirection(midBox);
if (midBox.Box.Volume > lowerBox.Box.Volume && midBox.Box.Volume > upperBox.Box.Volume)
{
break;
}
if (!DifferentMembershipInExtrema(lowerBox, midBox))
{
lowerBox = midBox;
}
else if (!DifferentMembershipInExtrema(upperBox, midBox))
{
upperBox = midBox;
}
else
{
throw new Exception("new midbox is different from BOTH neighbors!");
}
}
if (thisBoxData.Box.Volume < minBox.Volume)
{
minBox = midBox.Box;
}
}
thisBoxData = nextBoxData;
if (thisBoxData.Box.Volume < minBox.Volume)
{
minBox = thisBoxData.Box;
}
} while (angle < totalAngle);
}
return(minBox);
}
