/// <summary>
/// Split the polygon.
/// </summary>
/// <param name="poly">The Polygon</param>
/// <param name="part">The Part</param>
/// <param name="backPoly">The Back Polygon</param>
/// <param name="frontPoly">The Front Polygon</param>
private static void SplitPolygon(Polygon3D poly, Polygon3D part, out Polygon3D[] backPoly, out Polygon3D[] frontPoly)
{
var backP = new List <Polygon3D>();
var frontP = new List <Polygon3D>();
// this code looks for points which lie on the part plane and divide polygon into two parts
if (poly.Points != null)
{
var polyPoints = new List <Vector3DIndexClassification>();
var backPartPoints = new List <Vector3DIndexClassification>();
var frontPartPoints = new List <Vector3DIndexClassification>();
var outpts = new List <Vector3D>();
var inpts = new List <Vector3D>();
var count = poly.Points.Length;
for (var i = 0; i < count; i++)
{
var ptB = poly.Points[i];
var ptC = poly.Points[BspTreeBuilder.GetNext(i + 1, count)];
var sideB = ClassifyPoint(ptB, part);
var sideC = ClassifyPoint(ptC, part);
var vwiwcB = new Vector3DIndexClassification(ptB, polyPoints.Count, sideB);
polyPoints.Add(vwiwcB);
if ((sideB != sideC) && (sideB != ClassifyPointResult.OnPlane) &&
(sideC != ClassifyPointResult.OnPlane))
{
var v = ptB - ptC;
var dir = part.Normal * (-part.D) - ptC;
var sv = dir & part.Normal;
var sect = sv / (part.Normal & v);
var ptP = ptC + v * sect;
var vwiwc = new Vector3DIndexClassification(
ptP,
polyPoints.Count,
ClassifyPointResult.OnPlane);
polyPoints.Add(vwiwc);
backPartPoints.Add(vwiwc);
frontPartPoints.Add(vwiwc);
}
else
if (sideB == ClassifyPointResult.OnPlane)
{
var ptA = poly.Points[BspTreeBuilder.GetNext(i - 1, count)];
var sideA = ClassifyPoint(ptA, part);
if ((sideA == sideC))
{
continue;
}
if ((sideA != ClassifyPointResult.OnPlane) && (sideC != ClassifyPointResult.OnPlane))
{
backPartPoints.Add(vwiwcB);
frontPartPoints.Add(vwiwcB);
}
else
if (sideA == ClassifyPointResult.OnPlane)
{
switch (sideC)
{
case ClassifyPointResult.OnBack:
backPartPoints.Add(vwiwcB);
break;
case ClassifyPointResult.OnFront:
frontPartPoints.Add(vwiwcB);
break;
}
}
else
if (sideC == ClassifyPointResult.OnPlane)
{
switch (sideA)
{
case ClassifyPointResult.OnBack:
backPartPoints.Add(vwiwcB);
break;
case ClassifyPointResult.OnFront:
frontPartPoints.Add(vwiwcB);
break;
}
}
}
}
if ((frontPartPoints.Count != 0) || (backPartPoints.Count != 0))
{
for (var i = 0; i < backPartPoints.Count - 1; i += 2)
{
var vwiwc1 = backPartPoints[i];
var vwiwc2 = backPartPoints[i + 1];
vwiwc1.CuttingBackPoint = true;
vwiwc2.CuttingBackPoint = true;
vwiwc1.CuttingBackPairIndex = vwiwc2.Index;
vwiwc2.CuttingBackPairIndex = vwiwc1.Index;
}
for (var i = 0; i < frontPartPoints.Count - 1; i += 2)
{
var vwiwc1 = frontPartPoints[i];
var vwiwc2 = frontPartPoints[i + 1];
vwiwc1.CuttingFrontPoint = true;
vwiwc2.CuttingFrontPoint = true;
vwiwc1.CuttingFrontPairIndex = vwiwc2.Index;
vwiwc2.CuttingFrontPairIndex = vwiwc1.Index;
}
for (var i = 0; i < backPartPoints.Count - 1; i++)
{
var vwiwc = backPartPoints[i];
if (vwiwc.AlreadyCuttedBack)
{
continue;
}
BspTreeBuilder.CutOutBackPolygon(polyPoints, vwiwc, outpts);
if (outpts.Count > 2)
{
var points = outpts.ToArray();
var polygon = new Polygon3D(points, poly);
polygon.CalcNormal(points[0], points[1], points[2]);
polygon.CalcNormal();
backP.Add(polygon);
}
}
for (var i = 0; i < frontPartPoints.Count - 1; i++)
{
var vwiwc = frontPartPoints[i];
if (vwiwc.AlreadyCuttedFront)
{
continue;
}
BspTreeBuilder.CutOutFrontPolygon(polyPoints, vwiwc, inpts);
if (inpts.Count > 2)
{
var points = inpts.ToArray();
var polygon = new Polygon3D(points, poly);
polygon.CalcNormal(points[0], points[1], points[2]);
polygon.CalcNormal();
frontP.Add(polygon);
}
}
}
}
else
{
backP.Add(poly);
frontP.Add(poly);
}
backPoly = backP.ToArray();
frontPoly = frontP.ToArray();
}
/// <summary>
/// Cuts the out front polygon.
/// </summary>
/// <param name="polyPoints">The poly points.</param>
/// <param name="vwiwc">The Vertical Index Classification.</param>
/// <param name="points">The points.</param>
private static void CutOutFrontPolygon(List <Vector3DIndexClassification> polyPoints, Vector3DIndexClassification vwiwc, List <Vector3D> points)
{
points.Clear();
var curVW = vwiwc;
while (true)
{
curVW.AlreadyCuttedFront = true;
points.Add(curVW.Vector);
var curVWPair = polyPoints[curVW.CuttingFrontPairIndex];
if (curVW.CuttingFrontPoint)
{
if (!curVWPair.AlreadyCuttedFront)
{
curVW = curVWPair;
}
else
{
var curVWPrev = polyPoints[BspTreeBuilder.GetNext(curVW.Index - 1, polyPoints.Count)];
var curVWNext = polyPoints[BspTreeBuilder.GetNext(curVW.Index + 1, polyPoints.Count)];
if ((curVWPrev.Result == ClassifyPointResult.OnFront) && !curVWPrev.AlreadyCuttedFront)
{
curVW = curVWPrev;
}
else
if ((curVWNext.Result == ClassifyPointResult.OnFront) && !curVWNext.AlreadyCuttedFront)
{
curVW = curVWNext;
}
else
{
return;
}
}
}
else
{
var curPrev = polyPoints[BspTreeBuilder.GetNext(curVW.Index - 1, polyPoints.Count)];
var curNext = polyPoints[BspTreeBuilder.GetNext(curVW.Index + 1, polyPoints.Count)];
if ((curPrev.Result != ClassifyPointResult.OnBack) && !curPrev.AlreadyCuttedFront)
{
curVW = curPrev;
}
else
if ((curNext.Result != ClassifyPointResult.OnBack) && !curNext.AlreadyCuttedFront)
{
curVW = curNext;
}
else
{
return;
}
}
}
}
