Dear all,
Trying to use different StateSet with different osgText::Text objects it
happens that all text objects transparently may share the same StateSet
depending on how the state sets are created.
Image that we have two text objects t1 and t2, then the following
calling sequences behave as follows:
Case 1
t1->getOrCreateStateSet()
// t2 with the default empty state set
t1 will have a new StateSet and t2 will inherit it from its parent.
Case 2
t1->getOrCreateStateSet()
t2->getOrCreateStateSet()
Both texts will use the same state
Case 3
t1->setStateSet(a_state)
t2->getOrCreateStateSet()
Each object will have its own state.
Case 4
t1->getOrCreateStateSet()
t2->setStateSet(a_state)
Each object will have its own state.
Case 5
t1 // created first no stateset assigned
t2->getOrCreateStateSet()
Both texts will use the same state
While it may make sense, it seems a bit weird to me.
If this is the expected behaviour I couldn't find where does it say so
in the reference. Is it actually supposed to work like that and what is
the reason behind it?
Thanks and regards,
Juan
PS I attach a simple program in case someone wants to verify my statements.
#include <osgViewer/Viewer>
#include <osgText/Text>
#include <osgText/Font>
#include <osg/ShapeDrawable>
#include <osg/Geode>
#include <osg/Depth>
#include <osg/Material>
#include <iostream>
int main()
{
osgViewer::Viewer viewer;
osg::Geode *geode = new osg::Geode();
geode->addDrawable
(new osg::ShapeDrawable(new osg::Box(osg::Vec3(0, 0, 0), 20, 20, 20)));
osgText::Text *text1 = new osgText::Text();
text1->setText("label1");
text1->setPosition(osg::Vec3(10, 10, 10));
text1->setAxisAlignment(osgText::Text::SCREEN);
geode->addDrawable(text1);
// Uncommenting this line and commeting the other two below will cause
// both labels to share the same text.
//state = text1->getOrCreateStateSet();
osg::StateSet *state = new osg::StateSet();
//text1->setStateSet(state);
//state->setAttributeAndModes
// (new osg::Depth(osg::Depth::ALWAYS, 0, 1, false));
osg::Material *material = new osg::Material();
//material->setDiffuse(osg::Material::FRONT, osg::Vec4(1, 0, 0, 1));
//state->setAttributeAndModes(material);
osgText::Text *text2 = new osgText::Text();
text2->setText("label2");
text2->setPosition(osg::Vec3(-10, -10, -10));
text2->setAxisAlignment(osgText::Text::SCREEN);
geode->addDrawable(text2);
material = new osg::Material();
material->setDiffuse(osg::Material::FRONT, osg::Vec4(0, 0, 1, 1));
state = text2->getOrCreateStateSet();
state->setAttributeAndModes(material);
viewer.setSceneData(geode);
viewer.run();
}
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