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Mesh: add method to get intersection of edges

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This commit is contained in:
wmayer
2021-10-19 19:22:21 +02:00
parent 057cce2538
commit fe070903d3
2 changed files with 109 additions and 6 deletions
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99
src/Mod/Mesh/App/Core/Elements.cpp
View File

@@ -280,6 +280,61 @@ bool MeshGeomEdge::IntersectWithLine (const Base::Vector3f &rclPt,
return dist2 + dist3 <= dist1 + eps;
}
bool MeshGeomEdge::IntersectWithEdge (const MeshGeomEdge &edge, Base::Vector3f &res) const
{
const float eps = 1e-06f;
Base::Vector3f p(_aclPoints[0]);
Base::Vector3f r(_aclPoints[1] - _aclPoints[0]);
Base::Vector3f q(edge._aclPoints[0]);
Base::Vector3f s(edge._aclPoints[1] - edge._aclPoints[0]);
Base::Vector3f n = r.Cross(s);
Base::Vector3f d = q - p;
// lines are collinear or parallel
if (n.IsNull()) {
if (d.Cross(r).IsNull()) {
// Collinear
if (IsProjectionPointOf(edge._aclPoints[0])) {
res = edge._aclPoints[0];
return true;
}
if (IsProjectionPointOf(edge._aclPoints[1])) {
res = edge._aclPoints[1];
return true;
}
return false;
}
else {
// Parallel
return false;
}
}
else {
// Get the distance of q to the plane defined by p and n
float distance = q.DistanceToPlane(p, n);
// lines are warped
if (fabs(distance) > eps)
return false;
float t = d.Cross(s).Dot(n) / n.Sqr();
float u = d.Cross(r).Dot(n) / n.Sqr();
auto is_in_range = [](float v) {
return v >= 0.0f && v <= 1.0f;
};
if (is_in_range(t) && is_in_range(u)) {
res = p + t * r;
res = q + u * s;
return true;
}
return false;
}
}
bool MeshGeomEdge::IntersectWithPlane (const Base::Vector3f &rclPt,
const Base::Vector3f &rclDir,
Base::Vector3f &rclRes) const
@@ -370,6 +425,14 @@ bool MeshGeomEdge::IsPointOf (const Base::Vector3f &rclPoint, float fDistance) c
return Base::Distance(ptEdge, rclPoint) <= fDistance;
}
bool MeshGeomEdge::IsProjectionPointOf(const Base::Vector3f& point) const
{
Base::Vector3f fromStartToPoint = point - _aclPoints[0];
Base::Vector3f fromPointToEnd = _aclPoints[1] - point;
float dot = fromStartToPoint * fromPointToEnd;
return dot >= 0.0f;
}
// -----------------------------------------------------------------
MeshGeomFacet::MeshGeomFacet ()
@@ -1010,9 +1073,31 @@ int MeshGeomFacet::IntersectWithFacet (const MeshGeomFacet& rclFacet,
// Note: tri_tri_intersect_with_isection() does not return line of
// intersection when triangles are coplanar. See tritritest.h:18 and 658.
// So rclPt* may be garbage values and we cannot continue.
if (coplanar)
return 2; // equivalent to rclPt0 != rclPt1
if (coplanar) {
// Since tri_tri_intersect_with_isection may return garbage values try to get
// sensible values with edge/edge intersections
std::vector<Base::Vector3f> intersections;
for (short i=0; i<3; i++) {
MeshGeomEdge edge1 = GetEdge(i);
for (short j=0; j<3; j++) {
MeshGeomEdge edge2 = rclFacet.GetEdge(j);
Base::Vector3f point;
if (edge1.IntersectWithEdge(edge2, point)) {
intersections.push_back(point);
}
}
}
if (intersections.size() == 2) {
rclPt0 = intersections[0];
rclPt1 = intersections[1];
}
else if (intersections.size() == 1) {
rclPt0 = intersections[0];
rclPt1 = intersections[0];
}
return 2;
}
// With extremely acute-angled triangles it may happen that the algorithm
// claims an intersection but the intersection points are far outside the
@@ -1281,6 +1366,14 @@ void MeshGeomFacet::NearestEdgeToPoint(const Base::Vector3f& rclPt, float& fDist
}
}
MeshGeomEdge MeshGeomFacet::GetEdge(short side) const
{
MeshGeomEdge edge;
edge._aclPoints[0] = this->_aclPoints[side %3];
edge._aclPoints[1] = this->_aclPoints[(side+1)%3];
return edge;
}
float MeshGeomFacet::VolumeOfPrism (const MeshGeomFacet& rclF1) const
{
Base::Vector3f P1 = this->_aclPoints[0];

16
src/Mod/Mesh/App/Core/Elements.h
View File

@@ -168,6 +168,10 @@ public:
* with the edge. The intersection must be inside the edge. If there is no intersection false is returned.
*/
bool IntersectWithLine (const Base::Vector3f &rclPt, const Base::Vector3f &rclDir, Base::Vector3f &rclRes) const;
/** Calculates the intersection point of an edge with this edge.
* The intersection must be inside both edges. If there is no intersection false is returned.
*/
bool IntersectWithEdge (const MeshGeomEdge &edge, Base::Vector3f &res) const;
/** Calculates the intersection point of the plane defined by the base \a rclPt and the direction \a rclDir
* with the edge. The intersection must be inside the edge. If there is no intersection false is returned.
*/
@@ -185,11 +189,15 @@ public:
void ClosestPointsToLine(const Base::Vector3f &linePt, const Base::Vector3f &lineDir,
Base::Vector3f& rclPnt1, Base::Vector3f& rclPnt2) const;
/**
* Checks if the point is part of the facet. A point is regarded as part
* of a facet if the distance is lower \a fDistance and the projected point
* in the facet normal direction is inside the triangle.
* Checks if the point is part of the edge. A point is regarded as part
* of an edge if the distance is lower than \a fDistance to the projected point
* of \a rclPoint on the edge.
*/
bool IsPointOf (const Base::Vector3f &rclPoint, float fDistance) const;
/**
* Checks if the projection point of \a point lies on the edge.
*/
bool IsProjectionPointOf(const Base::Vector3f& point) const;
public:
Base::Vector3f _aclPoints[2]; /**< Corner points */
@@ -506,6 +514,8 @@ public:
unsigned short NearestEdgeToPoint(const Base::Vector3f& rclPt) const;
/** Returns the edge number \a side of the facet and the distance to the edge that is nearest to the point \a rclPt. */
void NearestEdgeToPoint(const Base::Vector3f& rclPt, float& fDistance, unsigned short& side) const;
/** Returns the edge for \a side. */
MeshGeomEdge GetEdge(short side) const;
/** The center and radius of the circum circle define a sphere in 3D. If the point \a rP is part of this sphere true is
* returned, otherwise false.
*/