// Construct an elliptical arc as a segment of an existing ellipse object
public QDEllipticalArc(QDEllipse parent, SweepDirection dir, float startAngle, float finishAngle)
{
constructFromFoci(parent.mFoci1, parent.mFoci2, parent.mFociToCirc);
direction = dir;
mStartAngleD = startAngle;
mFinishAngleD = finishAngle;
}
/**
* Finds the beginning angle of an elliptical arc given its direction, searching points near
* the first drawn point in case of small backtracks
*/
private float findArcEndD(SweepDirection direction, QDInputPointSet ptSet, QDEllipse ellipse)
{
float finishAngle = QDUtils.QDUtils.getPtToPtAngleD(ellipse.mCentre, ptSet.pts.Last());
if (direction == SweepDirection.Clockwise)
{
// Check for any points near the first point more CCW than the current to set as start
for (int i = ptSet.pts.Count - 2; i > Math.Floor(ptSet.pts.Count * 0.75f); i--)
{
float thisAngle = QDUtils.QDUtils.getPtToPtAngleD(ellipse.mCentre, ptSet.pts[i]);
if (QDUtils.QDUtils.angleDiffMinorD(finishAngle, thisAngle) < 0f)
{
finishAngle = thisAngle;
}
}
}
else if (direction == SweepDirection.Counterclockwise)
{ // CCW arc
for (int i = ptSet.pts.Count - 2; i > Math.Floor(ptSet.pts.Count * 0.75f); i--)
{
float thisAngle = QDUtils.QDUtils.getPtToPtAngleD(ellipse.mCentre, ptSet.pts[i]);
if (QDUtils.QDUtils.angleDiffMinorD(finishAngle, thisAngle) > 0f)
{
finishAngle = thisAngle;
}
}
}
return(finishAngle);
}
/**
* Finds the final angle of an elliptical arc given its direction, searching points near
* the last drawn point in case of small backtracks
*/
private float findArcStartD(SweepDirection direction, QDInputPointSet ptSet, QDEllipse ellipse)
{
float startAngle = QDUtils.QDUtils.getPtToPtAngleD(ellipse.mCentre, ptSet.pts[0]);
if (direction == SweepDirection.Clockwise)
{
// Check for any points near the first point more CCW than the current to set as start
for (int i = 1; i < Math.Ceiling(ptSet.pts.Count * 0.25f); i++)
{
float thisAngle = QDUtils.QDUtils.getPtToPtAngleD(ellipse.mCentre, ptSet.pts[i]);
if (QDUtils.QDUtils.angleDiffMinorD(startAngle, thisAngle) > 0f)
{
startAngle = thisAngle;
}
}
}
else if (direction == SweepDirection.Counterclockwise)
{ // CCW arc
for (int i = 1; i < Math.Ceiling(ptSet.pts.Count * 0.25f); i++)
{
float thisAngle = QDUtils.QDUtils.getPtToPtAngleD(ellipse.mCentre, ptSet.pts[i]);
if (QDUtils.QDUtils.angleDiffMinorD(startAngle, thisAngle) < 0f)
{
startAngle = thisAngle;
}
}
}
return(startAngle);
}
/**
* Find angle swept by points around the centre of an elliptical arc. Used to determine
* Whether it should be treated as a full ellipse or an arc
*/
private float findSweptArc(QDInputPointSet ptSet, QDEllipse ellipse)
{
QDPoint centre = ellipse.mCentre;
List <QDPoint> pts = ptSet.pts;
float lastAngle = QDUtils.QDUtils.getPtToPtAngleD(pts[0], centre);
float angleSweep = 0f;
foreach (QDPoint pt in pts)
{
float angle = QDUtils.QDUtils.getPtToPtAngleD(pt, centre);
angleSweep += QDUtils.QDUtils.angleDiffMinorD(angle, lastAngle);
lastAngle = angle;
}
return(angleSweep);
}
