Hi Stefan,
stefan nortd schrieb:
> So I found some code for intersecting a line with a plane.
> What I am missing is how do I translate the mouse pointer
> coordinates into a line expressed in local coordinates?
>
> Here the intersection code if anybody is interested:
There's a class called osg::Plane which you can use to do some
plane-ray-intersections:
double dist = _dragPlane.distance(mouseloc);
double numerator = -dist;
double denominator = _dragPlane.getNormal() * normalizedMouseRay;
if (0.0 == denominator) { // is on Plane
return true;
}
else
{
pointOnDragPlane = mouseloc + (normalizedMouseRay *
numerator/denominator);
}
the plane, mouseloc and normalizedMouseRay are in local coordinates.
To convert the mouseloc into local coordinates you'll have to
backproject the coordinates.
I do this via:
// get the coords in screen-space:
float tx = cefix::MouseLocationProvider::instance()->getNativeX();
float ty = cefix::MouseLocationProvider::instance()->getNativeY();
osg::Vec3 mouseloc = osg::Vec3(tx, ty, 0) * _invMatrix;
osg::Vec3 normalizedMouseRay = (osg::Vec3(tx, ty, 1) * _invMatrix) -
mouseloc;
The last question which remains: where comes _invMatrix from:
I get the nodepath of the picked object (it's basically a list of
transforms which affects this specific node) and compute a
localToWorld-matrix. I need the current cam to get view + projection matrix.
osg::Matrix MVPW = osg::computeLocalToWorld(nodepath) *
cam->getViewMatrix() * cam->getProjectionMatrix();
// include the viewport:
if (cam->getViewport())
MVPW.postMult(cam->getViewport()->computeWindowMatrix());
_inverseMat.invert(MVPW);
This code is basically the same as in osg, where picking is done.
cheers,
Stephan
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