Changes to camera parameters in OSG

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2. #pragma comment (lib, "Osg.lib")
4. #pragma comment (lib, "OsgDB.lib")
6. #pragma comment (lib, "OsgViewer.lib")
10. #include "Osgviewer/viewer"
12. #include "Osgdb/readfile"
14. #include "Osg/node"
16. #include "Osg/shape"
18. #include "Osg/geode"
20. #include "osg/shapedrawable"
24. int main () {
28. //Initialize the scene viewer
30. osg::ref_ptr<osgviewer::viewer> viewer=New Osgviewer::viewer;
34. //Initialize the scene root node
36. osg::ref_ptr<osg::group> root=New Osg::group;
40. //Scene data
42. Osg::ref_ptr<osg::node> node=osgdb::readnodefile ("GLIDER.OSG");
46. Root->addchild (node);
50. //Add scene data to the Vista
52. Viewer->setscenedata (root);
56. //Get the camera default parameter settings
58. Osg::vec3d Eye,center,up;
60. Viewer->getcamera ()->getviewmatrixaslookat (eye,center,up);
64. //Print out the camera parameters
66. printf ("init Eye:%f,%f,%f\n", eye._v[0],eye._v[1],eye._v[2]);
68. printf ("Init Center:%f,%f,%f\n", center._v[0],center._v[1],center._v[2]);
70. printf ("init up:%f,%f,%f\n", up._v[0],up._v[1],up._v[2]);
74. //Modify camera Parameters
76. Eye=osg::vec3d (0.0,-10.0,0.0);
78. Center=osg::vec3d (0.0,0.0,0.0);
80. Up=osg::vec3d (0.0,0.0,1.0);
84. //Set the parameters to the camera and get the camera parameters immediately
86. Viewer->getcamera ()->setviewmatrixaslookat (eye,center,up);
88. Viewer->getcamera ()->getviewmatrixaslookat (eye,center,up);
92. //Print out the parameters
94. printf ("Eye:%f,%f,%f new\n", eye._v[0],eye._v[1],eye._v[2]);
96. printf ("Center:%f,%f,%f new\n", center._v[0],center._v[1],center._v[2]);
98. printf ("Up:%f,%f,%f new\n", up._v[0],up._v[1],up._v[2]);
102. //simulation loop, take care not to use Viewer->run (), if you use this parameter, all the changes on the camera above will be invalid
104. While (!viewer->done ())
106. {
108. Viewer->frame ();
110. }
116. return 1;
118. }

Results

The above code shows that the initial camera parameters are:

This parameter is not visible by default because the default coordinate system in OSG is this:

This way, if the eye is at the origin, center is not visible in the case of the z-axis negative half axis, so if you do not manually set the parameters you cannot see things. The code that sets the camera position is commented out as follows:

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2. #pragma comment (lib, "Osg.lib")
4. #pragma comment (lib, "OsgDB.lib")
6. #pragma comment (lib, "OsgViewer.lib")
10. #include "Osgviewer/viewer"
12. #include "Osgdb/readfile"
14. #include "Osg/node"
16. #include "Osg/shape"
18. #include "Osg/geode"
20. #include "osg/shapedrawable"
24. int main () {
28. //Initialize the scene viewer
30. osg::ref_ptr<osgviewer::viewer> viewer=New Osgviewer::viewer;
34. //Initialize the scene root node
36. osg::ref_ptr<osg::group> root=New Osg::group;
40. //Scene data
42. Osg::ref_ptr<osg::node> node=osgdb::readnodefile ("GLIDER.OSG");
46. Root->addchild (node);
50. //Add scene data to the Vista
52. Viewer->setscenedata (root);
56. //Get the camera default parameter settings
58. Osg::vec3d Eye,center,up;
60. Viewer->getcamera ()->getviewmatrixaslookat (eye,center,up);
64. //Print out the camera parameters
66. printf ("init Eye:%f,%f,%f\n", eye._v[0],eye._v[1],eye._v[2]);
68. printf ("Init Center:%f,%f,%f\n", center._v[0],center._v[1],center._v[2]);
70. printf ("init up:%f,%f,%f\n", up._v[0],up._v[1],up._v[2]);
74. ////Modifying camera parameters
76. //eye=osg::vec3d (0.0,-10.0,0.0);
78. //center=osg::vec3d (0.0,0.0,0.0);
80. //up=osg::vec3d (0.0,0.0,1.0);
84. ////set parameters to the camera and get the camera parameters immediately
86. //viewer->getcamera ()->setviewmatrixaslookat (eye,center,up);
88. //viewer->getcamera ()->getviewmatrixaslookat (eye,center,up);
92. ////to print out parameters
94. //printf ("Eye:%f,%f,%f new\n", eye._v[0],eye._v[1],eye._v[2]);
96. //printf ("Center:%f,%f,%f new\n", center._v[0],center._v[1],center._v[2]);
98. //printf ("Up:%f,%f,%f new\n", up._v[0],up._v[1],up._v[2]);
102. //simulation loop, take care not to use Viewer->run (), if you use this parameter, all the changes on the camera above will be invalid
104. While (!viewer->done ())
106. {
108. Viewer->frame ();
110. }
116. return 1;
118. }

In this case the effect is like, nothing is seen:

After using the following set of test data:

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1. modifying camera parameters
2. Eye=osg::vec3d ( -10.0,0.0,0.0);
3. Center=osg::vec3d (0.0,0.0,0.0);
4. Up=osg::vec3d (0.0,0.0,1.0);

That is, from the x-axis negative half-axis, see should be the front of the aircraft, the effect such as:

Normal. In this case, there is no bots in the scene, there is no default bots this argument, if you need to implement the scene roaming, you can add a robot.

Note: If used directly:

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1. Viewer->run ();

How to modify the camera parameters is not valid,
Even if you add

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1. Viewer->setcameramanipulator (NULL);

is also the same because in

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1. Viewer->run ();

This function will judge whether a robot is present in the scene, and if it does not have a bot, it will add a trackballmanipulator bot itself.

The run function is implemented as follows:

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1. int Viewer::run ()
2. {
3. if (!getcameramanipulator () && Getcamera ()->getalloweventfocus ())
4. {
5. Setcameramanipulator (new Osgga::trackballmanipulator ());
6. }
8. Setreleasecontextatendofframehint (false);
10. return Viewerbase::run ();
11. }

It's easy to see where the problem lies.

Changes to camera parameters in OSG