[osg-users] setViewMatrixAsLookAt not working to set the initial camera position

[Rodrigo Dias]

Hi,

I'm able to change the camera's position with TrackballManipulator. However, I'd like to change the camera's initial position, but all the examples I've found just won't work. My source code is:


Code:
#include <iostream>
#include <osg/Camera>
#include <osgDB/ReadFile>
#include <osgGA/TrackballManipulator>
#include <osgViewer/Viewer>
#include <osgEarth/ImageLayer>
#include <osgEarth/Map>
#include <osgEarth/MapNode>
#include <osgEarthDrivers/tms/TMSOptions>
#include <osgEarthDrivers/gdal/GDALOptions>

using namespace std;
using namespace osg;
using namespace osgEarth;
using namespace osgEarth::Drivers;

int main (int argc, char** argv) {
MapOptions mapOpt;
mapOpt.coordSysType() = MapOptions::CSTYPE_PROJECTED;
mapOpt.profile() = ProfileOptions("plate-carre");
osg::ref_ptr<Map> map = new Map(mapOpt);
{
GDALOptions gdal;
gdal.url() = "br_modified.tif";
osg::ref_ptr<ImageLayer> layer = new ImageLayer( "BR", gdal );
map->addLayer( layer );
}
{
GDALOptions gdal;
gdal.url() = "BRalt.tif";
osg::ref_ptr<ElevationLayer> layer = new ElevationLayer( "SRTM", gdal );
map->addLayer( layer );
}
osg::ref_ptr<MapNode> mapNode = new MapNode( map );
osgViewer::Viewer viewer;
viewer.setSceneData( mapNode.get() );
viewer.setCameraManipulator( new osgGA::TrackballManipulator );

Vec3 eye( 10000.0, 50000.0, 100000.0 ); // The position of your camera
Vec3 center( 0.0, 0.0, 0.0 ); // The point your camera is looking at
Vec3 up( 0.0, 1.0, 0.0 ); // The up-vector of your camera - this controls how your viewport will be rotated about its center and should be equal to [0, 1, 0] in a conventional graphics coordinate system
viewer.getCamera()->setViewMatrixAsLookAt( eye, center, up );
while ( !viewer.done() ) {
viewer.frame();
}
return 0;
}




No matter which values I use for "eye", the camera always begins in the same position. Why is that?

Thank you!

Cheers,
Rodrigo

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=75411#75411





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[sam]

Hey Rodrigo,

You have to set the home position of your camera manipulator and make a call to home(1). You can force the delta time with a 1.

Sam

[Rodrigo Dias]

Hi Sam,

By "home" I think you mean


Code:
viewer.getCameraManipulator()->setHomePosition( eye, center, up );




This really changed camera's position, though it's totally freaking out now (I'm still fiddling with the values in eye, center and up).

But I have no idea what you meant by "delta time", something to go inside the loop?

Thank you!

Cheers,
Rodrigo

------------------
Read this topic online here:

http://forum.openscenegraph.org/viewtopic.php?p=75413#75413

[sam]

After you set the home position try: viewer.getCameraManipulator()->home(1);

Sorry I'm not right in front of my computer right now.

[Rodrigo Dias]

I just tried it, but still the camera is messed up. No matter which numbers I choose to eye, center and up, it never behaves as default. I have not even a clue about the difference between 10, 100 and 1000, which one should I use? (I'm using osgEarth's Map and MapNode, btw, which are displaying a whole flat white Earth, with only the desired country drawn with a texture) I tried using getViewMatrixAsLookAt with the default values, but it's still a mess. I've looked at many questions here, and in some of the source code, but nothing clears this up.

Thank you!

Cheers,
Rodrigo

------------------
Read this topic online here:

http://forum.openscenegraph.org/viewtopic.php?p=75415#75415

[Rodrigo Dias]

Back at it again...

I'm using a Brazil georeferenced map, so I know what coordinates are good enough to be above the country, high enough to see it all, looking down:

(...)

    osgViewer::Viewer viewer;
    viewer.setSceneData( root.get() );
    osg::ref_ptr<OVNIController> controller = new OVNIController(&viewer); // my own WASD flying controller
    viewer.setCameraManipulator(controller);
    viewer.getCamera()->setViewMatrixAsLookAt( osg::Vec3(-55.0f,-15.0f,50.0f), osg::Vec3(), osg::Y_AXIS ); // eye (lon, lat, alt), center, up
    viewer.getCameraManipulator()->home(1);
    viewer.realize();

    while ( !viewer.done() ) { viewer.frame(); }
    return 0;

I don't know if setViewMatrixAsLookAt() and home() should go before or after realize(). Played with the axis as 3rd parameter for setViewMatrixAsLookAt, but the camera just won't move! Any help, please?