/// <summary>
/// Construct a solid by sweeping a face along a curve.
/// </summary>
/// <param name="perimeter">The perimeter of the face to sweep.</param>
/// <param name="holes">The holes of the face to sweep.</param>
/// <param name="curve">The curve along which to sweep.</param>
/// <param name="startSetback">The setback distance of the sweep from the start of the curve.</param>
/// <param name="endSetback">The setback distance of the sweep from the end of the curve.</param>
/// <returns>A solid.</returns>
public static Solid SweepFaceAlongCurve(Polygon perimeter,
IList <Polygon> holes,
ICurve curve,
double startSetback = 0,
double endSetback = 0)
{
var solid = new Solid();
var l = curve.Length();
// The start and end setbacks can't be more than
// the length of the beam together.
if ((startSetback + endSetback) >= l)
{
startSetback = 0;
endSetback = 0;
}
// Calculate the setback parameter as a percentage
// of the curve length. This will not work for curves
// without non-uniform parameterization.
var ssb = startSetback / l;
var esb = endSetback / l;
var transforms = curve.Frames(ssb, esb);
if (curve is Polygon)
{
for (var i = 0; i < transforms.Length; i++)
{
var next = i == transforms.Length - 1 ? transforms[0] : transforms[i + 1];
solid.SweepPolygonBetweenPlanes(perimeter, transforms[i], next);
}
}
else if (curve is Bezier)
{
var startCap = solid.AddFace(perimeter, transform: transforms[0]);
for (var i = 0; i < transforms.Length - 1; i++)
{
var next = transforms[i + 1];
solid.SweepPolygonBetweenPlanes(perimeter, transforms[i], next);
}
var endCap = solid.AddFace(perimeter, transform: transforms[transforms.Length - 1], reverse: true);
}
else
{
// Add start cap.
Face cap = null;
Edge[][] openEdges;
if (holes != null)
{
cap = solid.AddFace(perimeter, holes, transform: transforms[0]);
openEdges = new Edge[1 + holes.Count][];
}
else
{
cap = solid.AddFace(perimeter, transform: transforms[0]);
openEdges = new Edge[1][];
}
// last outer edge
var openEdge = cap.Outer.GetLinkedEdges();
openEdge = solid.SweepEdges(transforms, openEdge);
openEdges[0] = openEdge;
if (holes != null)
{
for (var i = 0; i < cap.Inner.Length; i++)
{
openEdge = cap.Inner[i].GetLinkedEdges();
// last inner edge for one hole
openEdge = solid.SweepEdges(transforms, openEdge);
openEdges[i + 1] = openEdge;
}
}
solid.Cap(openEdges, true);
}
return(solid);
}
/// <summary>
/// Compute the difference of two solids.
/// </summary>
/// <param name="a">The first solid.</param>
/// <param name="aTransform">A local transformation of a.</param>
/// <param name="b">The second solid.</param>
/// <param name="bTransform">A local transformation of b.</param>
/// <returns>A solid which is the difference of a and b.</returns>
public static Solid Difference(Solid a, Transform aTransform, Solid b, Transform bTransform)
{
var allFaces = Intersect(a, aTransform, b, bTransform);
var s = new Solid();
// Group the faces according to their classification.
// AOutsideB for everything outside B which should remain.
// AInsideB for everything inside A which should become a hole.
var outsideFaces = allFaces.Where(o => o.classification == SetClassification.AOutsideB).ToList();
// TODO: The following is a hack because our Polygon.IntersectOneToMany
// method returns overlapping polygons where there are disjoint polygons.
var insideFaces = allFaces.Where(i => i.classification == SetClassification.AInsideB).ToList();
foreach (var(polygon, classification, coplanarClassification) in outsideFaces)
{
if (insideFaces.Count == 0)
{
s.AddFace(polygon, mergeVerticesAndEdges: true);
}
else
{
var plane = polygon._plane;
var holes = new List <Polygon>();
foreach (var insideFace in insideFaces)
{
if (polygon.Contains3D(insideFace.polygon))
{
// We need to do this edge overlap check to ensure
// that we're not making a profile where the openings
// overlaps the edges of the perimeter, creating a face
// with zero thickness between the outer and inner
// loops.
var hasEdgeOverlap = false;
foreach (var(from, to) in polygon.Edges())
{
foreach (var edge in insideFace.polygon.Edges())
{
if (from.DistanceTo(edge, out _).ApproximatelyEquals(0) && to.DistanceTo(edge, out _).ApproximatelyEquals(0))
{
hasEdgeOverlap = true;
break;
}
}
}
if (!hasEdgeOverlap)
{
if (plane.Normal.Dot(insideFace.polygon._plane.Normal).ApproximatelyEquals(1.0))
{
holes.Add(insideFace.polygon.Reversed());
}
else
{
holes.Add(insideFace.polygon);
}
}
}
}
s.AddFace(polygon, holes, mergeVerticesAndEdges: true);
}
}
// TODO: Can we invert the faces first?
var bInsideFaces = allFaces.Where(o => o.classification == SetClassification.BInsideA).ToList();
foreach (var(polygon, classification, coplanarClassification) in bInsideFaces)
{
s.AddFace(polygon.Reversed(), mergeVerticesAndEdges: true);
}
var result = MergeCoplanarFaces(allFaces, Difference);
if (result != null)
{
foreach (var(perimeter, holes) in result)
{
s.AddFace(perimeter, holes, mergeVerticesAndEdges: true);
}
}
return(s);
}
/// <summary>
/// Construct a solid by sweeping a face in a direction.
/// </summary>
/// <param name="perimeter">The perimeter of the face to sweep.</param>
/// <param name="holes">The holes of the face to sweep.</param>
/// <param name="direction">The direction in which to sweep.</param>
/// <param name="distance">The distance to sweep.</param>
/// <param name="bothSides">Should the sweep start offset by direction distance/2? </param>
/// <param name="rotation">An optional rotation in degrees of the perimeter around the direction vector.</param>
/// <returns>A solid.</returns>
public static Solid SweepFace(Polygon perimeter,
IList <Polygon> holes,
Vector3 direction,
double distance,
bool bothSides = false,
double rotation = 0.0)
{
// We do a difference of the polygons
// to get the clipped shape. This will fail in interesting
// ways if the clip creates two islands.
// if(holes != null)
// {
// var newPerimeter = perimeter.Difference(holes);
// perimeter = newPerimeter[0];
// holes = newPerimeter.Skip(1).Take(newPerimeter.Count - 1).ToArray();
// }
var solid = new Solid();
Face fStart = null;
if (bothSides)
{
var t = new Transform(direction.Negate() * (distance / 2), rotation);
if (holes != null)
{
fStart = solid.AddFace((Polygon)perimeter.Reversed().Transformed(t), t.OfPolygons(holes.Reversed()));
}
else
{
fStart = solid.AddFace((Polygon)perimeter.Reversed().Transformed(t));
}
}
else
{
if (holes != null)
{
fStart = solid.AddFace(perimeter.Reversed(), holes.Reversed());
}
else
{
fStart = solid.AddFace(perimeter.Reversed());
}
}
var fEndOuter = solid.SweepLoop(fStart.Outer, direction, distance);
if (holes != null)
{
var fEndInner = new Loop[holes.Count];
for (var i = 0; i < holes.Count; i++)
{
fEndInner[i] = solid.SweepLoop(fStart.Inner[i], direction, distance);
}
solid.AddFace(fEndOuter, fEndInner);
}
else
{
solid.AddFace(fEndOuter);
}
return(solid);
}
private static List <(Polygon polygon, SetClassification classification, CoplanarSetClassification coplanarClassification)> Intersect(Solid a,
Transform aTransform,
Solid b,
Transform bTransform)
{
var allFaces = new List <(Polygon, SetClassification, CoplanarSetClassification)>();
// TODO: Don't create polygons. Operate on the loops and edges directly.
// TODO: Support holes. We drop the inner loop information here currently.
// An explanation of what's going on here.
// At a high level, the act of intersecting two solids is the intersection and splitting
// of the solid's faces against those of the other solid, and the classification of the
// split pieces as:
// A inside B (ex. a piece of A which is inside B)
// A outside B
// B inside A
// B outside A
// A coplanar B
// B coplanar A
// 1. Sort the faces of a and b into two collections -> non-coplanar faces, and co-planar faces.
// 2. Split and classify each non-coplanar face of a against all the faces of b which it intersects.
// 3. Split and classify each non-coplanar face of b against all the faces of a which it intersects.
// 3. Intersect coplanar faces or return faces which are contained in other coplanar faces. Coplanar faces
// contained within other faces, will become holes.
var aFaces = a.Faces.Select(f => f.Value.Outer.ToPolygon(aTransform)).ToList();
var bFaces = b.Faces.Select(f => f.Value.Outer.ToPolygon(bTransform)).ToList();
var aCoplanarFaces = aFaces.Where(af => bFaces.Any(bf => bf._plane.IsCoplanar(af._plane))).ToList();
var bCoplanarFaces = bFaces.Where(bf => aFaces.Any(af => af._plane.IsCoplanar(bf._plane))).ToList();
var aNonCoplanar = aFaces.Except(aCoplanarFaces).ToList();
var bNonCoplanar = bFaces.Except(bCoplanarFaces).ToList();
foreach (var af in aNonCoplanar)
{
var classifications = af.IntersectAndClassify(bNonCoplanar.Where(bf => bf._bounds.Intersects(af._bounds)).ToList(),
bFaces,
out _,
out _,
SetClassification.AOutsideB,
SetClassification.AInsideB);
allFaces.AddRange(classifications);
}
foreach (var bf in bNonCoplanar)
{
var classifications = bf.IntersectAndClassify(aNonCoplanar.Where(af => af._bounds.Intersects(bf._bounds)).ToList(),
aFaces,
out _,
out _,
SetClassification.BOutsideA,
SetClassification.BInsideA);
allFaces.AddRange(classifications);
}
var aCoplanarFaceSets = aCoplanarFaces.GroupBy(af => af._plane.Normal);
var bCoplanarFaceSets = bCoplanarFaces.GroupBy(af => af._plane.Normal);
foreach (var aCoplanarFaceSet in aCoplanarFaceSets)
{
foreach (var aFace in aCoplanarFaceSet)
{
var bCoplanarFaceSet = bCoplanarFaceSets.FirstOrDefault(x => x.Key == aCoplanarFaceSet.Key);
if (bCoplanarFaceSet != null)
{
foreach (var bFace in bCoplanarFaceSet)
{
// The b face is completely contained within the a face, or is outside of it.
// In the former case, we return the face to become a hole. In the latter case,
// we return the face to become a stand-alone face.
if (aFace.Contains3D(bFace) || !aFace._bounds.Intersects(bFace._bounds))
{
var aa = (aFace, SetClassification.None, CoplanarSetClassification.ACoplanarB);
var bb = (bFace, SetClassification.None, CoplanarSetClassification.BCoplanarA);
if (!allFaces.Contains(aa))
{
allFaces.Add(aa);
}
if (!allFaces.Contains(bb))
{
allFaces.Add(bb);
}
}
// The b face intersects the a face. We do a planar intersection of the two faces, which
// adds new vertices to the a face and the b face. These faces are marked as coplanar,
// for later 2D boolean operations.
else if (aFace.Intersects2d(bFace, out List <(Vector3 result, int aSegumentIndices, int bSegmentIndices)> planarIntersectionResults, false))
{
var result = planarIntersectionResults.Select(r => r.result).ToList();
aFace.Split(result);
allFaces.Add((aFace, SetClassification.None, CoplanarSetClassification.ACoplanarB));
bFace.Split(result);
allFaces.Add((bFace, SetClassification.None, CoplanarSetClassification.BCoplanarA));
}
}
}
}
}
return(allFaces);
}
internal static Csg.Solid ToCsg(this Solid solid)
{
var polygons = new List <Csg.Polygon>();
foreach (var f in solid.Faces.Values)
{
if (f.Inner != null && f.Inner.Count() > 0)
{
var tess = new Tess
{
NoEmptyPolygons = true
};
tess.AddContour(f.Outer.ToContourVertexArray());
foreach (var loop in f.Inner)
{
tess.AddContour(loop.ToContourVertexArray());
}
tess.Tessellate(WindingRule.Positive, LibTessDotNet.Double.ElementType.Polygons, 3);
Vector3 e1 = new Vector3();
Vector3 e2 = new Vector3();
var vertices = new List <Csg.Vertex>(tess.Elements.Count() * 3);
for (var i = 0; i < tess.ElementCount; i++)
{
var a = tess.Vertices[tess.Elements[i * 3]].ToCsgVector3();
var b = tess.Vertices[tess.Elements[i * 3 + 1]].ToCsgVector3();
var c = tess.Vertices[tess.Elements[i * 3 + 2]].ToCsgVector3();
Csg.Vertex av = null;
Csg.Vertex bv = null;
Csg.Vertex cv = null;
if (i == 0)
{
var n = f.Plane().Normal;
e1 = n.Cross(n.IsParallelTo(Vector3.XAxis) ? Vector3.YAxis : Vector3.XAxis).Unitized();
e2 = n.Cross(e1).Unitized();
}
if (av == null)
{
var avv = new Vector3(a.X, a.Y, a.Z);
av = new Csg.Vertex(a, new Csg.Vector2D(e1.Dot(avv), e2.Dot(avv)));
vertices.Add(av);
}
if (bv == null)
{
var bvv = new Vector3(b.X, b.Y, b.Z);
bv = new Csg.Vertex(b, new Csg.Vector2D(e1.Dot(bvv), e2.Dot(bvv)));
vertices.Add(bv);
}
if (cv == null)
{
var cvv = new Vector3(c.X, c.Y, c.Z);
cv = new Csg.Vertex(c, new Csg.Vector2D(e1.Dot(cvv), e2.Dot(cvv)));
vertices.Add(cv);
}
var p = new Csg.Polygon(new List <Csg.Vertex>()
{
av, bv, cv
});
polygons.Add(p);
}
}
else
{
var verts = new List <Csg.Vertex>(f.Outer.Edges.Count);
var n = f.Plane().Normal;
var e1 = n.Cross(n.IsParallelTo(Vector3.XAxis) ? Vector3.YAxis : Vector3.XAxis).Unitized();
var e2 = n.Cross(e1).Unitized();
foreach (var e in f.Outer.Edges)
{
var l = e.Vertex.Point;
var v = new Csg.Vertex(l.ToCsgVector3(), new Csg.Vector2D(e1.Dot(l), e2.Dot(l)));
verts.Add(v);
}
var p = new Csg.Polygon(verts);
polygons.Add(p);
}
}
return(Csg.Solid.FromPolygons(polygons));
}
