/// <summary>
/// This will find the largest turn in a given models. It prefers concave turns to convex turns.
/// If turn amount is the same, bias towards the smallest y position.
/// </summary>
/// <param name="inputPolygon">The polygon to analyze</param>
/// <param name="considerAsSameY">Range to treat y positions as the same value.</param>
/// <param name="startPosition">If two or more angles are similar, choose the one close to the start</param>
/// <returns>The position that has the largest turn angle</returns>
public static int FindGreatestTurnIndex(this Polygon inputPolygon,
long extrusionWidth_um = 3,
IntPoint?startPosition = null)
{
var count = inputPolygon.Count;
var positiveGroup = new CandidateGroup(extrusionWidth_um);
var negativeGroup = new CandidateGroup(extrusionWidth_um / 4);
// look for relatively big concave turns
DiscoverAndAddTurns(inputPolygon,
extrusionWidth_um * 4,
negativeGroup,
delta => delta < -extrusionWidth_um / 2);
if (negativeGroup.Count == 0)
{
// look for relatively big convex turns
DiscoverAndAddTurns(inputPolygon,
extrusionWidth_um * 4,
positiveGroup,
delta => delta > extrusionWidth_um * 2);
if (positiveGroup.Count == 0)
{
negativeGroup.SameDelta = extrusionWidth_um / 16;
// look for small concave turns
DiscoverAndAddTurns(inputPolygon,
extrusionWidth_um,
negativeGroup,
delta => delta < -extrusionWidth_um / 8);
}
}
if (negativeGroup.Count > 0)
{
return(negativeGroup.GetBestIndex(startPosition));
}
else if (positiveGroup.Count > 0)
{
return(positiveGroup.GetBestIndex(startPosition));
}
else
{
var currentFurthestBack = new IntPoint(long.MaxValue, long.MinValue);
int furthestBackIndex = 0;
// get the furthest back index
for (var i = 0; i < count; i++)
{
var currentPoint = inputPolygon[i];
if (currentPoint.Y >= currentFurthestBack.Y)
{
if (currentPoint.Y > currentFurthestBack.Y ||
currentPoint.X < currentFurthestBack.X)
{
furthestBackIndex = i;
currentFurthestBack = currentPoint;
}
}
}
// If can't find good candidate go with vertex most in a single direction
return(furthestBackIndex);
}
}
/// <summary>
/// This will find the largest turn in a given models. It prefers concave turns to convex turns.
/// If turn amount is the same bias towards the smallest y position.
/// </summary>
/// <param name="inputPolygon"></param>
/// <param name="considerAsSameY">Range to treat y positions as the same value.</param>
/// <returns></returns>
public static IntPoint FindGreatestTurnPosition(this Polygon inputPolygon, long considerAsSameY, int layerIndex, IntPoint?startPosition = null)
{
Polygon currentPolygon = Clipper.CleanPolygon(inputPolygon, considerAsSameY / 8);
// collect & bucket options and then choose the closest
if (currentPolygon.Count == 0)
{
return(inputPolygon[0]);
}
double totalTurns = 0;
CandidateGroup positiveGroup = new CandidateGroup(DegreesToRadians(35));
CandidateGroup negativeGroup = new CandidateGroup(DegreesToRadians(10));
IntPoint currentFurthestBack = new IntPoint(long.MaxValue, long.MinValue);
int furthestBackIndex = 0;
double minTurnToChoose = DegreesToRadians(1);
long minSegmentLengthToConsiderSquared = 50 * 50;
int pointCount = currentPolygon.Count;
for (int pointIndex = 0; pointIndex < pointCount; pointIndex++)
{
int prevIndex = ((pointIndex + pointCount - 1) % pointCount);
int nextIndex = ((pointIndex + 1) % pointCount);
IntPoint prevPoint = currentPolygon[prevIndex];
IntPoint currentPoint = currentPolygon[pointIndex];
IntPoint nextPoint = currentPolygon[nextIndex];
if (currentPoint.Y >= currentFurthestBack.Y)
{
if (currentPoint.Y > currentFurthestBack.Y ||
currentPoint.X < currentFurthestBack.X)
{
furthestBackIndex = pointIndex;
currentFurthestBack = currentPoint;
}
}
long lengthPrevToCurSquared = (prevPoint - currentPoint).LengthSquared();
long lengthCurToNextSquared = (nextPoint - currentPoint).LengthSquared();
bool distanceLongeEnough = lengthCurToNextSquared > minSegmentLengthToConsiderSquared && lengthPrevToCurSquared > minSegmentLengthToConsiderSquared;
double turnAmount = currentPoint.GetTurnAmount(prevPoint, nextPoint);
totalTurns += turnAmount;
if (turnAmount < 0)
{
// threshold angles, don't pick angles that are too shallow
// threshold line lengths, don't pick big angles hiding in TINY lines
if (Math.Abs(turnAmount) > minTurnToChoose &&
distanceLongeEnough)
{
negativeGroup.ConditionalAdd(new CandidatePoint(turnAmount, pointIndex, currentPoint));
}
}
else
{
if (Math.Abs(turnAmount) > minTurnToChoose &&
distanceLongeEnough)
{
positiveGroup.ConditionalAdd(new CandidatePoint(turnAmount, pointIndex, currentPoint));
}
}
}
if (negativeGroup.Count > 0)
{
if (positiveGroup.Count > 0
// the negative group is a small turn and the positive group is a big turn
&& ((Math.Abs(negativeGroup[0].turnAmount) < Math.PI / 4 &&
Math.Abs(positiveGroup[0].turnAmount) > Math.PI / 4)
// the negative turn amount is very small
|| Math.Abs(negativeGroup[0].turnAmount) < Math.PI / 8))
{
// return the positive rather than the negative turn
return(currentPolygon[positiveGroup.GetBestIndex(layerIndex, startPosition)]);
}
return(currentPolygon[negativeGroup.GetBestIndex(layerIndex, startPosition)]);
}
else if (positiveGroup.Count > 0)
{
return(currentPolygon[positiveGroup.GetBestIndex(layerIndex, startPosition)]);
}
else
{
// If can't find good candidate go with vertex most in a single direction
return(currentPolygon[furthestBackIndex]);
}
}
/// <summary>
/// This will find the largest turn in a given models. It prefers concave turns to convex turns.
/// If turn amount is the same, bias towards the smallest y position.
/// </summary>
/// <param name="inputPolygon">The polygon to analyze</param>
/// <param name="considerAsSameY">Range to treat y positions as the same value.</param>
/// <param name="startPosition">If two or more angles are similar, choose the one close to the start</param>
/// <returns>The position that has the largest turn angle</returns>
public static int FindGreatestTurnIndex(this Polygon inputPolygon,
int layerIndex = 0,
long extrusionWidth_um = 3,
SEAM_PLACEMENT seamPlacement = SEAM_PLACEMENT.FURTHEST_BACK,
IntPoint?startPosition = null)
{
var count = inputPolygon.Count;
if (seamPlacement == SEAM_PLACEMENT.ALWAYS_CENTERED_IN_BACK)
{
return(inputPolygon.GetCenteredInBackIndex(out _));
}
var positiveGroup = new CandidateGroup(extrusionWidth_um);
var negativeGroup = new CandidateGroup(extrusionWidth_um / 4);
// look for relatively big concave turns
DiscoverAndAddTurns(inputPolygon,
extrusionWidth_um * 4,
negativeGroup,
delta => delta < -extrusionWidth_um / 2);
if (negativeGroup.Count == 0)
{
// look for relatively big convex turns
DiscoverAndAddTurns(inputPolygon,
extrusionWidth_um * 4,
positiveGroup,
delta => delta > extrusionWidth_um * 2);
if (positiveGroup.Count == 0)
{
negativeGroup.SameDelta = extrusionWidth_um / 16;
// look for small concave turns
DiscoverAndAddTurns(inputPolygon,
extrusionWidth_um,
negativeGroup,
delta => delta < -extrusionWidth_um / 8);
if (seamPlacement == SEAM_PLACEMENT.RANDOMIZED)
{
// look for very small concave turns
DiscoverAndAddTurns(inputPolygon,
extrusionWidth_um,
negativeGroup,
delta => delta < -extrusionWidth_um / 32);
// choose at random which point to pick
if (negativeGroup.Count > 1)
{
var selectedPoint = (int)(inputPolygon.GetLongHashCode(layerIndex.GetLongHashCode()) % (ulong)negativeGroup.Count);
var singlePoint = negativeGroup[selectedPoint];
// remove every point except the random one we want
negativeGroup.Clear();
negativeGroup.Add(singlePoint);
}
}
}
}
if (negativeGroup.Count > 0)
{
return(negativeGroup.GetBestIndex(startPosition));
}
else if (positiveGroup.Count > 0)
{
return(positiveGroup.GetBestIndex(startPosition));
}
else // there is no really good candidate
{
switch (seamPlacement)
{
case SEAM_PLACEMENT.CENTERED_IN_BACK:
return(inputPolygon.GetCenteredInBackIndex(out _));
case SEAM_PLACEMENT.RANDOMIZED:
return((int)(inputPolygon.GetLongHashCode(layerIndex.GetLongHashCode()) % (ulong)inputPolygon.Count));
case SEAM_PLACEMENT.FURTHEST_BACK:
default:
var currentFurthestBack = new IntPoint(long.MaxValue, long.MinValue);
int furthestBackIndex = 0;
// get the furthest back index
for (var i = 0; i < count; i++)
{
var currentPoint = inputPolygon[i];
if (currentPoint.Y >= currentFurthestBack.Y)
{
if (currentPoint.Y > currentFurthestBack.Y ||
currentPoint.X < currentFurthestBack.X)
{
furthestBackIndex = i;
currentFurthestBack = currentPoint;
}
}
}
// If can't find good candidate go with vertex most in a single direction
return(furthestBackIndex);
case SEAM_PLACEMENT.FASTEST:
if (startPosition != null)
{
return(inputPolygon.FindClosestIndex(startPosition.Value));
}
return(0);
}
}
}