Hi Jake,
I think boundig boxes are only used at Drawable and Geode level because they
are AABB (that is axis aligned bboxes). Testing collisions between rotated
arbitrary bounding boxes or adding groups of them gets tricky, so they are
kept at the local coordinate system. When you want to collide some entities
in the world coordinate system, it is easier to do so with bounding spheres
as you did first.
Nevertheless, you could write a visitor that transforms those bounding boxes
and checks them for collision by traversing the scene graph, as somewhat does
the IntersectVisitor but transforming the ray, not the boxes :)
El Jueves 27 Marzo 2008ES 13:40:22 Jacob Huckaby escribió:
> Hi,
>
> I am trying to use bounding boxes for simple collision detection with a
> very simple model. My model is composed of six boxes of various sizes. I
> have imported each box from a .osg file as a node. Each node is then
> parented to a MatrixTransform, which allows them to rotate along different
> axes. The MatrixTransforms then are parented to each other
> (box1->box2->box3, etc.)
>
> I was able to do this rough collision detection easily with bounding
> spheres:
>
> osg::Node* box1 = osgDB::readNodeFile("box1.osg");
> osg::MatrixTransform* rotateBox1 = new osg::MatrixTransform;
> rotateBox1->addChild(box1);
>
> osg::Node* box2 = osgDB::readNodeFile("box2.osg");
> osg::MatrixTransform* rotateBox2 = new osg::MatrixTransform;
> rotateBox2->addChild(box2);
>
> const osg::BoundingSphere& bs = rotateBox1->getBound();
> const osg::BoundingSphere& bs2 = rotateBox2->getBound();
> if(bs.intersects(bs2))
> {
> //Collision
> }
>
>
> My question: how can I do a similar test with bounding boxes?
>
>
> I read through as many of the archived posts as I could find, but I have
> been unable to find a solution. Bounding boxes would work perfectly for my
> situation (since my nodes are actually boxes) but work only for Drawables.
> I tried creating Box Shapes and parenting those to Geodes, which were then
> parented to the MatrixTransforms.
>
> osg::Box* box1 = new
> osg::Box(osg::Vec3(7.0f,0.0f,0.0f),8.5f,2.5f,2.5f); osg::ShapeDrawable*
> box1Drawable = new osg::ShapeDrawable(box1); osg::Geode* box1Geode = new
> osg::Geode;
> box1Geode->addDrawable(box1Draw able);
> rotateBox1->addChild(box1Geode);
>
> osg::Box* box2 = new
> osg::Box(osg::Vec3(1.0f,0.0f,0.0f),2.5f,2.5f,2.5f); osg::ShapeDrawable*
> box2Drawable = new osg::ShapeDrawable(box2); osg::Geode* box2Geode = new
> osg::Geode;
> box2Geode->addDrawable(box2Drawable);
> rotateBox2->addChild(box2Geode);
>
> const osg::BoundingBox& bb1 = box2Geode->getBoundingBox();
> const osg::BoundingBox& bb2 = box2Geode->getBoundingBox();
> if(bb1.intersects(bb2))
> {
> //Collision
> }
>
> This didn't work either. The bounding box did not seem to reflect what was
> shown in the scene (it said the boxes were intersecting whereas the scene
> showed them as not intersecting.) I don't need precise detection, or any
> kind of localization. This, and the ease of using Bounding box make it seem
> like a nice option. So how can I use bounding boxes in this situation?
>
> Thank you very much for your help,
>
> Jake
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