Hi Robert,
Attached is an osgtext.cpp that demonstrates the problem I'm seeing in our
application with text in SCREEN_COORDS scaling improperly.
In this particular app, we're using a FIXED projection matrix mapping (-1,-1)
to the lower-left corner, and (+1,+1) to the upper-right corner (ortho 2D). We
have a layout system in this application that uses matrix transforms to
position items in the layout.
In this section, the text is nested in two matrix transforms. These transforms
update values as a result of window resizes. I omitted this code because it
did not seem particularly relevant, and it is not required to reproduce the
behavior. I got the current values for both matrices by saving the scene to an
.osg file and extracting the subgraph.
What you're seeing in this app is 4 text labels that form the text part of a 2D
"compass", serving as a set of labels for a plot's X-axis. Obviously this is
just a subset of the whole scene.
When you resize the window with 3.6.1-rc2, you'll notice that the text skews
significantly. If you run the same app in OSG 3.4.1, the text looks correct
regardless of window size.
Side discovery -- setting the backdrop had a weird impact on text placement.
Not entirely sure that I understand why. It doesn't really impact us in our
application, but I thought I'd mention it just in case it's important.
- Dan
/* OpenSceneGraph example, osgtext.
*
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* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* furnished to do so, subject to the following conditions:
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <osgDB/ReadFile>
#include <osgGA/StateSetManipulator>
#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>
#include <osgViewer/config/SingleWindow>
#include <osg/Camera>
#include <osg/MatrixTransform>
#include <osgText/Font>
#include <osgText/Text>
osgText::Text* createText(const std::string& textString, float xPosition)
{
osgText::Text* returnValue = new osgText::Text;
returnValue->setDataVariance(osg::Object::DYNAMIC);
returnValue->setFont("fonts/times.ttf");
returnValue->setCharacterSize(32.f);
returnValue->setCharacterSizeMode(osgText::Text::SCREEN_COORDS);
returnValue->setPosition(osg::Vec3(xPosition, -0.05, 0.0));
returnValue->setAlignment(osgText::TextBase::CENTER_CENTER);
returnValue->setAutoRotateToScreen(true);
returnValue->setText(textString);
// Note that adding a drop shadow makes text's alignment pretty far off.
This does
// not seem to have a huge negative impact in my app, but was noticed during
the copy
// over to this demo. Probably just an artifact of only having text in the
scene?
//returnValue->setBackdropType(osgText::Text::DROP_SHADOW_BOTTOM_RIGHT);
return returnValue;
}
// create text which sits in 3D space such as would be inserted into a normal
model
osg::Group* create3DText()
{
osg::MatrixTransform* topXform = new osg::MatrixTransform;
topXform->setName("Top Level Transform");
// Real application adjusts this matrix on the fly as window resizes
topXform->setMatrix(osg::Matrix(
0.854637, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0.125313, 0, 0, 1
));
// In real app, there are nodes between these two transforms
osg::MatrixTransform* xformLayoutItem = new osg::MatrixTransform;
xformLayoutItem->setName("VerticalLayout LayoutItem");
// Real application adjusts this matrix on the fly as window resizes
xformLayoutItem->setMatrix(osg::Matrix(
1, 0, 0, 0,
0, 0.920716, 0, 0,
0, 0, 1, 0,
0, 0.774936, 0, 1
));
osgText::Text* text330 = createText("330", -0.166667);
osgText::Text* text000 = createText("000", 0.0);
osgText::Text* text030 = createText("030", 0.166667);
osgText::Text* text060 = createText("060", 0.333334);
topXform->addChild(xformLayoutItem);
xformLayoutItem->addChild(text330);
xformLayoutItem->addChild(text000);
xformLayoutItem->addChild(text030);
xformLayoutItem->addChild(text060);
return topXform;
}
int main(int argc, char** argv)
{
osg::ArgumentParser arguments(&argc, argv);
// construct the viewer.
osgViewer::Viewer viewer(arguments);
// make sure the root node is group so we can add extra nodes to it.
osg::Group* group = new osg::Group;
group->addChild(create3DText());
// set the scene to render
viewer.setSceneData(group);
viewer.addEventHandler(new
osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()));
viewer.addEventHandler(new osgViewer::StatsHandler());
viewer.addEventHandler(new osgViewer::WindowSizeHandler());
int width = 800;
int height = 600;
if (arguments.read("--size1"))
; // noop
else if (arguments.read("--size2"))
height = 100;
else if (arguments.read("--size3"))
width = 100;
viewer.setUpViewInWindow(100, 100, width, height);
// Configure an ortho-2D projection, using -1 and +1 as bounds
osg::Camera* camera = viewer.getCamera();
camera->getOrCreateStateSet()->setGlobalDefaults();
camera->setProjectionMatrixAsOrtho2D(-1.f, 1.f, -1.f, 1.f);
camera->setProjectionResizePolicy(osg::Camera::FIXED);
camera->setViewMatrixAsLookAt(
osg::Vec3d(0, 0, 100),
osg::Vec3d(0, 0, 0),
osg::Y_AXIS);
viewer.run();
return 0;
}
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