Hi Paul,
I'm afraid I can't easily follow your email, THE CAPTIALS DON'T
MAGICALLY MAKE IT EASIER TO FOLLOW, rather the opposite.
At a guess code it be simply that you aren't taking into account that
fact the that Intersections store the intersection in local
coordinates of the object intersect and your using this as a world
coordinate. The Intersection object does store the matrix that takes
the local coords into world, and also has a getWorldIntersectPoint()
as well as a getLocalIntersectPoint().
Robert.
On Wed, Oct 22, 2008 at 7:41 PM, DeBitetto, Paul A.
<[EMAIL PROTECTED]> wrote:
> Hi Folks,
>
>
>
> I am having trouble with Coordinate transformations when using the
> LineSegmentIntersector. I made a VERY simple one rectangular polygon test
> VRML model. I can load this fine into OSG and even save it as an .osg model
> and then reload it. The simple VRML code shown below at the bottom. Note I
> did not use any transformations (all comented out)..
>
>
>
> I'm assuming the rectangle is in the X-Y Plane and is longer in the X
> direction.
>
>
>
> In my test code, I call the LineSegmentIntersector simply as shown below
> with start and end points defined as
>
>
>
> osg::Vec3 start( 0, 0, -50);
>
> osg::Vec3 end( 0, 0,50 );
>
>
>
> So I assume this should create a line that runs in the +- Z direction and
> cuts through the center of the plane.
>
> here's the code snippet to call the lineSegmentIntersector
>
>
>
>
>
> osg::ref_ptr<osgUtil::LineSegmentIntersector> intersector =
>
> new osgUtil::LineSegmentIntersector(start, end);
>
>
>
> osgUtil::IntersectionVisitor intersectVisitor( intersector.get(),
>
> new MyReadCallback );
>
>
>
> root->accept(intersectVisitor);
>
> if ( intersector->containsIntersections() ){
>
> std:: cout << "INTERSECTS!\n";
>
> return true;
>
> }
>
> else{
>
> std:: cout << "no intersects\n";
>
> return false;
>
> }
>
>
>
> HERE'S THE PROBLEM. IN THE DISPLAY, THE PLANE AND INTERSECTING LINE LOOK
> CORRECT. HOWEVER THE INTERSECTOR RETURNS "NO INTERSECTION".
>
> HOWEVER IF I REVERSE THE Y AND Z COORDINATES IN THE START AND END POINTS,
> THEN IT RETURNS "INTERSECTION" AS IT SHOULD BUT THE DISPLAY LOOKS WRONG.
>
> THE LINE IS NOW PARALLEL TO THE PLANE AND NOT INTERSECTING. This leads me
> to think that the coordinate frame assumed by the LineSegmentIntersector to
> interpret the start,end points is different than the coordinate frame used
> for displaying the model.
>
>
>
> Can anyone shed some light as to why there would be a discrepancy between
> the coordinates used for display and those used by the intersector?? I could
> not find any details on coordinate frames in the documentation..
>
>
>
> Thanks in advance!
>
> Paul
>
>
>
> Here's the simple VRML model code..
>
>
>
> #VRML V2.0 utf8
>
>
>
> # Produced by 3D Studio MAX VRML97 exporter
>
> # modified by Bitmanagement Software GmbH, H. Grahn, Andrea Fasce,
> Version 5.01, Revision 0
>
> # MAX File: 1.10.2008-buildings.max, Date: Thu Jan 10 13:18:53 2008
>
>
>
> DEF bld_610_2 Transform {
>
> # translation 0 0 0
>
> # translation -2153.17 7.11304 -375.004
>
> # rotation 0 1 0 0
>
> # scale 0.0261872 0.0172898 0.0258266
>
> # scaleOrientation 1 0 0 0
>
> # rotation 0 0 1 -1.70056
>
> # scale 0.0261872 0.0172898 0.0258266
>
> # scale 1 1 1
>
> children [
>
> Shape {
>
> #Material 02 - Default
>
> appearance DEF MAT-_2___Default Appearance {
>
> material Material {
>
> diffuseColor 0.588 0.588 0.588
>
> ambientIntensity 1.0
>
> specularColor 0.95 0.95 0.95
>
> shininess 0.9
>
> }
>
> texture
>
> DEF _T-_10_2all ImageTexture {
>
> url "610-2all.jpg" }
>
> }
>
> ## render mesh bld_610_2
>
> geometry DEF bld_610_2-FACES IndexedFaceSet {
>
> coord DEF bld_610_2-COORD Coordinate { point [
>
> 100 -50 0, 100 50 0, -100 50 0, -100 -50 0 ]
>
> }
>
> texCoord DEF bld_610_2-TEXCOORD TextureCoordinate { point [
>
> .1 0, 0 .1, .2 0,.3 0 ]
>
> }
>
> coordIndex [
>
> 0, 1, 2, 3, -1, ]
>
> texCoordIndex [
>
> 0, 1, 2, 3,-1, ]
>
> }
>
> }
>
> ]
>
> }
>
>
>
> _______________________________________________
> osg-users mailing list
> [email protected]
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
>
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