/// <summary>
/// Gets the two portions of a closed contour corresponding to the part where the u-parameter is monotonic increasing and where it is monotonic decreasing.
/// </summary>
/// <param name="contourPoints">The set of points belonging to the contour. </param>
/// <param name="increasingChunk">The <see cref="ExtrudedContourMonotonicChunk"/> with increasing u-parameters. </param>
/// <param name="decreasingChunk">The <see cref="ExtrudedContourMonotonicChunk"/> with decreasing u-parameters. </param>
/// <returns> True if the two monotonic chunks were found; False if the contour points didn't consist of exactly two monotonic (in u-parameter) portions, one increasing and the other decreasing. </returns>
internal static bool GetExtrudedContourMonotonicChunks(IList <Vector2WithUV> contourPoints, out ExtrudedContourMonotonicChunk increasingChunk, out ExtrudedContourMonotonicChunk decreasingChunk)
{
increasingChunk = null;
decreasingChunk = null;
bool gotChunks = false;
int minUIndex = -1, maxUIndex = -1;
float minU = float.PositiveInfinity, maxU = float.NegativeInfinity;
bool isPeriodic = contourPoints[0].Equals(contourPoints[contourPoints.Count - 1]);
int numPoints = isPeriodic ? contourPoints.Count - 1 : contourPoints.Count;
if (numPoints > 0)
{
for (int i = 0; i < numPoints; i++)
{
var point = contourPoints[i];
var u = point.UV.x;
if (u < minU)
{
minU = u;
minUIndex = i;
}
if (u > maxU)
{
maxU = u;
maxUIndex = i;
}
}
Vector2WithUV previousPoint = contourPoints[minUIndex];
List <Vector2WithUV> increasingPoints = new List <Vector2WithUV>()
{
previousPoint
};
int maxIndexShifted = maxUIndex < minUIndex ? maxUIndex + numPoints : maxUIndex;
bool correctUDirection = true;
for (int increasingIndex = minUIndex + 1; increasingIndex <= maxIndexShifted; increasingIndex++)
{
var point = contourPoints[increasingIndex % numPoints];
if (point.UV.x >= previousPoint.UV.x)
{
increasingPoints.Add(point);
}
else
{
correctUDirection = false;
break;
}
}
if (correctUDirection)
{
increasingChunk = new ExtrudedContourMonotonicChunk(increasingPoints, minU, maxU, isReversed: false);
}
int minIndexShifted = minUIndex < maxUIndex ? minUIndex + numPoints : minUIndex;
previousPoint = contourPoints[minIndexShifted % numPoints];
List <Vector2WithUV> decreasingPoints = new List <Vector2WithUV>()
{
previousPoint
};
correctUDirection = true;
for (int decreasingIndex = minIndexShifted - 1; decreasingIndex >= maxUIndex; decreasingIndex--)
{
var point = contourPoints[decreasingIndex % numPoints];
if (point.UV.x >= previousPoint.UV.x)//Since we're going through decreasing points in reverse order
{
decreasingPoints.Add(point);
}
else
{
correctUDirection = false;
break;
}
}
if (correctUDirection)
{
decreasingChunk = new ExtrudedContourMonotonicChunk(decreasingPoints, minU, maxU, isReversed: true);
}
gotChunks = increasingChunk != null && decreasingChunk != null && increasingChunk.Points.Count >= 1 && decreasingChunk.Points.Count >= 1;
}
return(gotChunks);
}
/// <summary>
/// Returns if two connected segment points are close enough to be considered essentially duplicates.
/// </summary>
/// <param name="connectedSegmentPoint">A connected segment point.</param>
/// <param name="neighbouringConnectedSegmentPoint">A neighbouring connected segment point.</param>
private static bool ConnectedSegmentPointsAreClose(Vector2WithUV connectedSegmentPoint, Vector2WithUV neighbouringConnectedSegmentPoint)
{
const float epsilonDistance = 1e-5f;
const float epsilonU = 1e-5f;
bool withinDistance = (connectedSegmentPoint.Vector - neighbouringConnectedSegmentPoint.Vector).magnitude < epsilonDistance;
bool withinU = System.Math.Abs(connectedSegmentPoint.UV.x - neighbouringConnectedSegmentPoint.UV.x) < epsilonU;
return(withinDistance && withinU);
}
/// <summary>
/// For a contour consisting of one portion monotonically increasing in u-parameter and the other monotonically decreasing, return the <see cref="SingleContourSegmentwiseCoverage"/>
/// where there are matching points (at the same u-parameter) on both the increasing and decreasing portions.
/// </summary>
/// <param name="monotonicIncreasingChunk">Portion of contour with monotonically increasing u-parameters</param>
/// <param name="monotonicDecreasingChunk">Portion of contour with monotonically decreasing u-parameters</param>
internal static SingleContourSegmentwiseCoverage GetSingleContourSegmentwiseCoverage(ExtrudedContourMonotonicChunk monotonicIncreasingChunk, ExtrudedContourMonotonicChunk monotonicDecreasingChunk)
{
List <UParameterIndexAndMonotonicity> allContourPointUParameters = new List <UParameterIndexAndMonotonicity>();
List <Vector2WithUV> monotonicIncreasingPoints = monotonicIncreasingChunk.Points;
List <Vector2WithUV> monotonicDecreasingPoints = monotonicDecreasingChunk.Points;
//Skip the last point in each chunk so as to not double-count the 'endpoints' of min/max u-parameter
for (int i = 0; i < monotonicIncreasingPoints.Count - 1; i++)
{
allContourPointUParameters.Add(new UParameterIndexAndMonotonicity(monotonicIncreasingPoints[i].UV.x, i, true));
}
for (int i = 1; i < monotonicDecreasingPoints.Count; i++)
{
allContourPointUParameters.Add(new UParameterIndexAndMonotonicity(monotonicDecreasingPoints[i].UV.x, i, false));
}
allContourPointUParameters.Sort(CompareUParameterIndexAndMonotonicityByUParameter);
allContourPointUParameters.RemoveAt(allContourPointUParameters.Count - 1);
allContourPointUParameters.RemoveAt(0);
int numInBetweenUParameters = allContourPointUParameters.Count;
var firstPoint = monotonicIncreasingPoints[0];
var lastPoint = monotonicDecreasingPoints[monotonicDecreasingPoints.Count - 1];
List <Vector2WithUV> increasingChunkPoints = new List <Vector2WithUV>();
List <Vector2WithUV> decreasingChunkPoints = new List <Vector2WithUV>();
for (int i = 0; i < numInBetweenUParameters; i++)
{
UParameterIndexAndMonotonicity uParameterIndexAndMonotonicity = allContourPointUParameters[i];
ExtrudedContourMonotonicChunk givenMonotonicChunk = uParameterIndexAndMonotonicity.IsMonotonicIncreasing ? monotonicIncreasingChunk : monotonicDecreasingChunk;
ExtrudedContourMonotonicChunk otherMonotonicChunk = uParameterIndexAndMonotonicity.IsMonotonicIncreasing ? monotonicDecreasingChunk : monotonicIncreasingChunk;
Vector2WithUV givenMonotonicChunkPoint = givenMonotonicChunk.Points[uParameterIndexAndMonotonicity.Index];
Vector2WithUV matchingMonotonicChunkPoint;
bool gotMatchingPoint = otherMonotonicChunk.GetClosestPoint(uParameterIndexAndMonotonicity.UParameter, out matchingMonotonicChunkPoint);
if (gotMatchingPoint)
{
var increasingPoint = uParameterIndexAndMonotonicity.IsMonotonicIncreasing ? givenMonotonicChunkPoint : matchingMonotonicChunkPoint;
var decreasingPoint = uParameterIndexAndMonotonicity.IsMonotonicIncreasing ? matchingMonotonicChunkPoint : givenMonotonicChunkPoint;
increasingChunkPoints.Add(increasingPoint);
decreasingChunkPoints.Add(decreasingPoint);
}
}
//Now remove connected segments pairs that are effectively duplicates of a neighbouring segment
for (int i = increasingChunkPoints.Count - 1; i > 0; i--)
{
var increasingPoint = increasingChunkPoints[i];
var decreasingPoint = increasingChunkPoints[i];
var prevIncreasingPoint = increasingChunkPoints[i - 1];
var prevDecreasingPoint = increasingChunkPoints[i - 1];
bool increasingAreClose = ConnectedSegmentPointsAreClose(prevIncreasingPoint, increasingPoint);
bool decreasingAreClose = ConnectedSegmentPointsAreClose(prevDecreasingPoint, decreasingPoint);
if (increasingAreClose && decreasingAreClose)
{
increasingChunkPoints.RemoveAt(i);
decreasingChunkPoints.RemoveAt(i);
}
}
return(new SingleContourSegmentwiseCoverage(firstPoint, lastPoint, increasingChunkPoints, decreasingChunkPoints));
}
