Thu, 01/26/2006 - 19:42
I'm trying to pick a point on a shape.
I've read alot of good methods on the forum and have applied two methods one found on:
http://www.opencascade.org/org/forum/thread_2728/
and the other found on:
http://www.opencascade.org/org/forum/thread_8220/
I've used an algorithm that gets a 3D point (ResultPoint) on a plane orthogonal to the point of view.
From there I've decomposed the shape into faces (then surfaces) to use the GeomAPI_IntCS class to find the intersection between a "line" (from EyePoint to ResultPoint) and the given face.
The final ResultPoint I get is incorrect. It too seems to lies on a plane (it seems to be a plane that one of the faces is on).
Furthermore, "line" intersects with all of the faces in my shape. (currently I'm playing with a cube (12 triangles)).
Can somebody let me know where I'm going wrong here.
I've supplied the code that I'm using:
Thanks in advance
~Sinisa
aView->Eye(xEye, yEye, zEye);
aView->At(xAt, yAt, zAt);
gp_Pnt EyePoint(xEye, yEye, zEye);
gp_Pnt AtPoint(xAt, yAt, zAt);
gp_Vec EyeVector(EyePoint, AtPoint);
gp_Dir EyeDir(EyeVector);
gp_Pln PlaneOfView = gp_Pln(AtPoint, EyeDir);
Standard_Real theX, theY, theZ;
aView->Convert(x, y, theX, theY, theZ);
gp_Pnt ConvertedPoint (theX, theY, theZ);
gp_Pnt2d ConvertedPointOnPlane = ProjLib::Project(PlaneOfView, ConvertedPoint);
gp_Pnt ResultPoint = ElSLib::Value(ConvertedPointOnPlane.X(), ConvertedPointOnPlane.Y(), PlaneOfView);
GC_MakeLine line(EyePoint, ResultPoint);
TopExp_Explorer exp;
int iii = 0;
for (exp.Init(myShape, TopAbs_FACE); exp.More(); exp.Next())
{
TopoDS_Face face = TopoDS::Face(exp.Current());
BRepAdaptor_Surface surface(face);
const GeomAdaptor_Surface& geomAdapSurf = surface.Surface();
const Handle(Geom_Surface)& geomSurf = geomAdapSurf.Surface();
GeomAPI_IntCS inCS;
inCS.Perform(line, geomSurf);
if (inCS.IsDone())
{
if (inCS.NbPoints()!=0)
{
ResultPoint = gp_Pnt(inCS.Point(1).XYZ());
}
iii++;
}
}
a3dPoint = ResultPoint;
Thu, 03/02/2006 - 13:53
Hi Sinisa Stokic,
Firtly thanks for the posting, I trying to do something simular by picking point of a surface.
I and think I've got it fully working now, which just one simple change to the code.
//xGC_MakeLine line(EyePoint, ResultPoint); <--- change this line to
GC_MakeLine line(ResultPoint, EyeDir);
I've include the complete function, sorry about the C# code :), if you have any problems just send me an e-mail.
private global::Core.Geometry.Interfaces.ICoordinate ConvertClickToPoint2(
System.Drawing.Point position,
IView view,
global::OpenCASCADE52.Geom.Interfaces.IPlane geomSurface)
{
double xEye = 0.0;
double yEye = 0.0;
double zEye = 0.0;
double xAt = 0.0;
double yAt = 0.0;
double zAt = 0.0;
unsafe
{
view.Eye(&xEye, &yEye, &zEye);
view.At(&xAt, &yAt, &zAt);
}
IPnt eyePoint = new Pnt(xEye, yEye, zEye);
IPnt atPoint = new Pnt(xAt, yAt, zAt);
//DrawLine(eyePoint, atPoint);
Debug.WriteLine(string.Format("EyePoint: {0} {1} {2}", xEye, yEye, zEye));
Debug.WriteLine(string.Format("AtPoint: {0} {1} {2}", xAt, yAt, zAt));
IVec eyeVector = new Vec(eyePoint, atPoint);
IDir eyeDir = new Dir(eyeVector);
IPln planeOfTheView = new Pln(atPoint, eyeDir);
//DrawPlane(planeOfTheView);
double x, y, z;
unsafe
{
view.Convert(position.X, position.Y, &x, &y, &z);
}
Debug.WriteLine(string.Format("XYZ: {0} {1} {2}", x, y, z));
IPnt convertedPoint = new Pnt(x, y, z);
IPnt2d convertedPointOnPlane = ProjLib.Project(planeOfTheView, convertedPoint);
IPnt resultPoint = ElSLib.Value(convertedPointOnPlane.X, convertedPointOnPlane.Y, planeOfTheView);
//DrawLine(eyePoint, resultPoint);
//IMakeLine makeLine = new MakeLine(eyePoint, resultPoint); //x
IMakeLine makeLine = new MakeLine(resultPoint, eyeDir); // project backwards from the result point using the viewing plane
//DrawLine(makeLine);
IIntCS intCS = new IntCS();
intCS.Perform(makeLine.Value, geomSurface);
if( intCS.IsDone() )
{
if( intCS.NbPoints() > 0 )
{
resultPoint = new Pnt(intCS.Point(1).XYZ); // one-based
return new global::Core.Geometry.Coordinate(resultPoint.X, resultPoint.Y, resultPoint.Z);
}
}
return null;
}
Many thanks
Jonathan
Mon, 07/21/2008 - 11:02
hi
I had changed the line, but I can't get the correct result, are you sure the result is true? I use iges import model.
thanks!
Wed, 07/23/2008 - 11:40
hi
have the problem been solved?
Fri, 08/01/2008 - 19:44
No the problem still exists.