Alberto Luaces writes:
Hi,
I am in the process of creating a control panel for a simulator, using
osgWidget for drawing the controls.
I want to draw a turning knob, but it is not very clear how to specify
the origin for the rotation of the widget. By default, all the widgets
rotate over (0, 0), that is, their bottom-left corner.
Has anyone developed a widget similar to a compass or a speedometer with
osgWidget?
This is what I eventually got — subclassing the window and overwriting
the transform to fit my needs:
--8---cut here---start-8---
class window_pivot_center: public osgWidget::Box
{
public:
window_pivot_center(const std::string name): osgWidget::Box(name)
{}
void update()
{
osgWidget::Box::update();
osgWidget::point_type w, h;
w = getWidth();
h = getHeight();
osg::Matrix t = osg::Matrix::translate(-w/2, -h/2, 0);
osg::Matrix r = osg::Matrix::rotate(osg::DegreesToRadians(getRotate()), 0,
0, 1);
osg::Matrix tinv = osg::Matrix::translate(w/2, h/2, 0);
osgWidget::Point p = getPosition();
osg::Matrix pos = osg::Matrix::translate(p[0], p[1], 0);
setMatrix(t * r * tinv * pos);
}
};
--8---cut here---end---8---
--
Alberto
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