The intersectWith() function has two forms:
virtual Acad::ErrorStatus
intersectWith(
const AcDbEntity* ent,
AcDb::Intersect intType,
AcGePoint3dArray& points,
int thisGsMarker = 0,
int otherGsMarker = 0) const;
virtual Acad::ErrorStatus
intersectWith(
const AcDbEntity* ent,
AcDb::Intersect intType,
const AcGePlane& projPlane,
AcGePoint3dArray& points,
int thisGsMarker = 0,
int otherGsMarker = 0) const;
The first form of the intersectWith() function tests for simple intersection of two entities. The second form calculates the intersection on a projection plane. However, both functions return the intersection points on the entity itself. To implement custom behavior, override the corresponding subIntersectWith() function.
The custom AsdkPoly class overrides both forms of the subIntersectWith() function.
Acad::ErrorStatus
AsdkPoly::subIntersectWith(
const AcDbEntity* ent,
AcDb::Intersect intType,
AcGePoint3dArray& points,
int /*thisGsMarker*/,
int /*otherGsMarker*/) const
{
assertReadEnabled();
Acad::ErrorStatus es = Acad::eOk;
if (ent == NULL)
return Acad::eNullEntityPointer;
// The idea is to intersect each side of the polygon
// with the given entity and return all the points.
//
// For non-R12-entities, with
// intersection methods defined, we call that method for
// each of the sides of the polygon. For R12-entities,
// we use the locally defined intersectors, since their
// protocols are not implemented.
//
if (ent->isKindOf(AcDbLine::desc())) {
if ((es = intLine(this, AcDbLine::cast(ent),
intType, NULL, points)) != Acad::eOk)
{
return es;
}
} else if (ent->isKindOf(AcDbArc::desc())) {
if ((es = intArc(this, AcDbArc::cast(ent), intType,
NULL, points)) != Acad::eOk)
{
return es;
}
} else if (ent->isKindOf(AcDbCircle::desc())) {
if ((es = intCircle(this, AcDbCircle::cast(ent),
intType, NULL, points)) != Acad::eOk)
{
return es;
}
} else if (ent->isKindOf(AcDb2dPolyline::desc())) {
if ((es = intPline(this, AcDb2dPolyline::cast(ent),
intType, NULL, points)) != Acad::eOk)
{
return es;
}
} else if (ent->isKindOf(AcDb3dPolyline::desc())) {
if ((es = intPline(this, AcDb3dPolyline::cast(ent),
intType, NULL, points)) != Acad::eOk)
{
return es;
}
} else {
AcGePoint3dArray vertexArray;
if ((es = getVertices3d(vertexArray))
!= Acad::eOk)
{
return es;
}
if (intType == AcDb::kExtendArg
|| intType == AcDb::kExtendBoth)
{
intType = AcDb::kExtendThis;
}
AcDbLine *pAcadLine;
for (int i = 0; i < vertexArray.length() - 1; i++) {
pAcadLine = new AcDbLine();
pAcadLine->setStartPoint(vertexArray[i]);
pAcadLine->setEndPoint(vertexArray[i + 1]);
pAcadLine->setNormal(normal());
if ((es = ent->intersectWith(pAcadLine, intType,
points)) != Acad::eOk)
{
delete pAcadLine;
return es;
}
delete pAcadLine;
}
}
return es;
}
Acad::ErrorStatus
AsdkPoly::subIntersectWith(
const AcDbEntity* ent,
AcDb::Intersect intType,
const AcGePlane& projPlane,
AcGePoint3dArray& points,
int /*thisGsMarker*/,
int /*otherGsMarker*/) const
{
assertReadEnabled();
Acad::ErrorStatus es = Acad::eOk;
if (ent == NULL)
return Acad::eNullEntityPointer;
// The idea is to intersect each side of the polygon
// with the given entity and return all the points.
//
// For non-R12-entities, with
// intersection methods defined, we call that method for
// each of the sides of the polygon. For R12-entities,
// we use the locally defined intersectors, since their
// protocols are not implemented.
//
if (ent->isKindOf(AcDbLine::desc())) {
if ((es = intLine(this, AcDbLine::cast(ent),
intType, &projPlane, points)) != Acad::eOk)
{
return es;
}
} else if (ent->isKindOf(AcDbArc::desc())) {
if ((es = intArc(this, AcDbArc::cast(ent), intType,
&projPlane, points)) != Acad::eOk)
{
return es;
}
} else if (ent->isKindOf(AcDbCircle::desc())) {
if ((es = intCircle(this, AcDbCircle::cast(ent),
intType, &projPlane, points)) != Acad::eOk)
{
return es;
}
} else if (ent->isKindOf(AcDb2dPolyline::desc())) {
if ((es = intPline(this, AcDb2dPolyline::cast(ent),
intType, &projPlane, points)) != Acad::eOk)
{
return es;
}
} else if (ent->isKindOf(AcDb3dPolyline::desc())) {
if ((es = intPline(this, AcDb3dPolyline::cast(ent),
intType, &projPlane, points)) != Acad::eOk)
{
return es;
}
} else {
AcGePoint3dArray vertexArray;
if ((es = getVertices3d(vertexArray))
!= Acad::eOk)
{
return es;
}
if (intType == AcDb::kExtendArg
|| intType == AcDb::kExtendBoth)
{
intType = AcDb::kExtendThis;
}
AcDbLine *pAcadLine;
int i;
for (i = 0; i < vertexArray.length() - 1; i++) {
pAcadLine = new AcDbLine();
pAcadLine->setStartPoint(vertexArray[i]);
pAcadLine->setEndPoint(vertexArray[i + 1]);
pAcadLine->setNormal(normal());
if ((es = ent->intersectWith(pAcadLine, intType,
projPlane, points)) != Acad::eOk)
{
delete pAcadLine;
return es;
}
delete pAcadLine;
}
// All the points that we selected in this process are on
// the other curve; we are dealing with apparent
// intersection. If the other curve is 3D or is not
// on the same plane as poly, the points are not on
// poly.
//
// In this case, we need to do some more work. Project the
// points back onto the plane. They should lie on
// the projected poly. Find points on real poly
// corresponding to the projected points.
AcGePoint3d projPt, planePt;
AcGePoint3dArray pts;
AcGeLine3d line;
AcGePlane polyPlane;
AcDb::Planarity plnrty;
getPlane(polyPlane,plnrty);
for (i = 0; i < points.length(); i++) {
// Define a line starting from the projPt and
// along the normal. Intersect the polygon with
// that line. Find all the points and pick the
// one closest to the given point.
//
projPt = points[i].orthoProject(projPlane);
line.set(projPt, projPlane.normal());
if ((es = intLine(this, line, pts))
!= Acad::eOk)
{
return es;
}
planePt = projPt.project(polyPlane,
projPlane.normal());
points[i] = pts[0];
double length = (planePt - pts[0]).length();
double length2;
for (int j = 1; j < pts.length(); j++) {
if ((length2 = (planePt - pts[j]).length())
< length)
{
points[i] = pts[j];
length = length2;
}
}
}
}
return es;
}