Re: [osg-users] How to set camera focal length

[Igor Galochkin]

just found where the problem is:
Viewer.cpp, line 1023:  inside viewer.updateTraversals

  if (_cameraManipulator.valid())
{
setFusionDistance( getCameraManipulator()-getFusionDistanceMode(),
getCameraManipulator()-getFusionDistanceValue() );

_camera-setViewMatrix(_cameraManipulator-getInverseMatrix());
}

So, at each frame the camera's matrix is overwritten by a new matrix which is 
taken from MatrixManipulator.

I still wonder why viewer doesn't render anything at all (black image) if no 
MatrixManipulator is set.

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Re: [osg-users] How to set camera focal length

[Igor Galochkin]

Skylark wrote:
 
 Most likely your view matrix calculation has an error.
 


Yes, just found out the view matrix was wrong and the image was black because 
the camera was inside some object or something, and i first thought i am 
reading from a wrong buffer.

Sorry guys for bothering you with such simple stuff.

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Re: [osg-users] How to set camera focal length

[Igor Galochkin]

[quote=robertosfield]HI Igor,
 an osg::Camera
nor GL camera don't have a concept of a focal length.  
[quote]

Under Focal length I mean the distance from the camera's lens to it's focus. 
This distance can be different for x and y, for example, if the camera's lens 
is oval in shape. 

I have to write a function which receives, among other parameters, these 2 
values (x focal length and y focal length) and have to pass it somehow to the 
OSG viewer. Is there a way to do this at all?

If this is important, in the library for which i have to do this, the x axis 
goes from left to right of the screen, y axis goes form top to bottom of the 
screen and z axis goes away from the viewer.

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Re: [osg-users] How to set camera focal length

[Igor Galochkin]

Thanks for help!

I am setting the focal lense x and y with the following calls now and it seems 
to work fine:


double fovy = 2 * atan(this-_height / 2.0 / dFocalLengthY);
double aspectRatio = this-_nWidth / this-_nHeight * dFocalLengthY / 
dFocalLengthX;
double zNear = 0.1, zFar = 100.0;

_viewer.getCamera()-setProjectionMatrix(::osg::Matrix::perspective(fovy, 
aspectRatio, zNear, zFar));


But i still can't set up the position and rotation of the viewer's camera. 

this-_viewer.getCamera()-setReferenceFrame(::osg::Transform::ABSOLUTE_RF);
this-_viewer.getCamera()-setViewMatrix(::osg::Matrix::translate(0.5, 0.3, 
0.1));

this does nothing. 

My guess is becase i also have to call:

::osg::ref_ptr ::osgGA::KeySwitchMatrixManipulator keyswitchManipulator = new 
::osgGA::KeySwitchMatrixManipulator;

keyswitchManipulator-addMatrixManipulator( '1', Trackball, new 
::osgGA::TrackballManipulator() );

this-_viewer.setCameraManipulator( keyswitchManipulator.get() );

or the offscreen capture doesn't render the scene, just an empty background. It 
looks like viewer needs a camera manipulator or it won't render the scene.


Is it at all possible to move the camera programmatically after a camera 
manipulator has been set for the viewer? Or can i avoid creating a camera 
manipulator?

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[osg-users] Threads-related bug in screen capture?

[Igor Galochkin]

Hi guys,

I am writing a wrapper for screen capturing logic. I used osgscreencapture 
example as a start, and it works.

However, I am experiencing strange bugs:

1. if you order the viewer to change the background color 
viewer.getCamera()-setClearColor(::osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f);
and then call viewer.frame()
ther is a chance (not 100%!) that the screenshot will still have the old color. 
After you call viewer.frame() again, the screenshot has the new color.


2. If you first call viewer.setSceneData(NULL);
and then viewer.setSceneData(pNode); where pNode is a valid pointer to OSG 
scene,
you sometimes (again, not 100%!) still get an empty image (with no scene) if 
you call viewer.frame().


I suspect these bugs are related and show a more generic bug with threading. My 
guess would be that although .frame() call goes after the change to viewer's 
setting, somehow the frame() call uses old values.

I built up a small example which shows when these bugs appear by me.


Thank you!

Cheers,
Igor

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Re: [osg-users] Threads-related bug in screen capture?

[Igor Galochkin]

Hmm, after some testing I found out that the Images don't get their background 
updates only if END_FRAME is passed to WindowCaptureCallback.
With START_FRAME it works ok.

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Re: [osg-users] osgscreencapture sample doesn't work

[Igor Galochkin]

Thanks a lot, guys!
Yesterday i though i'd go mad, it was like hitting the head against a wall.. 
 But yes, i checked out the current subversion tomorrow morning and managed to 
write an image successfully under Windows with osgscreencapture.
Now it should be (hopefully) trivial to use it in my project.

Thanks for help and for the fix!

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Re: [osg-users] How to render the OSG scene to an image file?

[Igor Galochkin]

OK, the problem was with the bug in the Windows implementation of the 
PixelBuffer implementation. 
Checked out the latest version from SVN trunk (development one) and got 
osgscreencapture working under Windows.
Will use it now in my project.

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[osg-users] osgscreencapture sample doesn't work

[Igor Galochkin]

Hi,

I am trying to render the scene to an image without opening any windows. After 
doing a lot of searching and looking thru source code of OSG classes, I still 
get a completely white image.

In many places people say one should use the same code as there is in 
osgscreencapture which renders to a pbuffer is --pbuffer-only option is passed.

But the fact is that osgscreencapture doesn't work itself! 

osgscreencapture.exe axes.osg --pbuffer-only 640 480 

must produce an image without opening any windows.

When running this on my laptop (WindowsXP home) i get the following error 
message:
PixelBufferWin32::init(), Error: Couldn't find a suitable pixel format
Pixel buffer has not been created successfully.
Windows Error #2000: Win32WindowingSystem::OpenGLContext() - Unable to restore 
current OpenGL rendering context. Reason: Pixel format is invalid.

after that the axes.osg file is just opened in a full-screen viwer window, no 
image file is created.


When running this on my Desktop PC (WindowsXP Pro) i get the following error 
message:
Pixel buffer has been created successfully.
PixelBufferWin32::makeCurrentImplementation, wglMakeCurrent error: Die 
angeforderte Ressource wird bereits verwendet. (The requested resource is 
already being used)

Error: OpenGL version test failed, requires valid graphics context.
After that the program crashes and attempt to open Visual Studio debugger.

On both machines OSG is correctly installed, e.g. i can easily open the osg 
files in viewer by double clicking.

Do I at least call the osgscreenviewer correctly?


... 

Thank you!

Cheers,
Igor

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Re: [osg-users] How to render the OSG scene to an image file?

[Igor Galochkin]

The following piece of code writes the same error to the console:


Code:
!!! pbuffer is VALID!


PixelBufferWin32::makeCurrentImplementation, wglMakeCurrent error: Die angeforde
rte Ressource wird bereits verwendet.

Error: OpenGL version test failed, requires valid graphics context.
PixelBufferWin32::realizeImplementation, wglShareLists error: Die angeforderte R
essource wird bereits verwendet.

PixelBufferWin32::makeCurrentImplementation, wglMakeCurrent error: Die angeforde
rte Ressource wird bereits verwendet.



so, wglMakeCurrent(_hdc, _hglrc) fails in 
bool PixelBufferWin32::makeCurrentImplementation()

see
http://www.openscenegraph.org/svn/osg/OpenSceneGraph/tags/OpenSceneGraph-2.6.1/src/osgViewer/PixelBufferWin32.cpp

May this be a Windows bug or OSG's implementation for Windows bug? 




::osgViewer::Viewer * viewer = new ::osgViewer::Viewer();
viewer-setSceneData(pGeode);

::osg::ref_ptrSnapImageDrawCallback snapImageDrawCallback = new 
SnapImageDrawCallback(); 
viewer-getCamera()-setFinalDrawCallback 
(snapImageDrawCallback.get()); 

snapImageDrawCallback-setFileName(1.bmp); 
snapImageDrawCallback-setSnapImageOnNextFrame(true); 

::osg::ref_ptr ::osg::GraphicsContext pbuffer;

::osg::ref_ptr ::osg::GraphicsContext::Traits traits = new 
::osg::GraphicsContext::Traits;
traits-x = 0;
traits-y = 0;
traits-width = 640;
traits-height = 480;
traits-red = 8;
traits-green = 8;
traits-blue = 8;
traits-alpha = 8;
traits-windowDecoration = false;
traits-pbuffer = true;
traits-doubleBuffer = true;
traits-sharedContext = 0;

pbuffer = ::osg::GraphicsContext::createGraphicsContext(traits.get());

if (!pbuffer.valid())
{
::std::cout  \n\n!!! pbuffer is invalid!\n\n  std::endl;
return;
}
else
{
::std::cout  \n\n!!! pbuffer is VALID!\n\n  std::endl;
}

viewer-getCamera()-setGraphicsContext(pbuffer.get());
viewer-getCamera()-setViewport(new osg::Viewport(0,0,640,480));
GLenum buffer = pbuffer-getTraits()-doubleBuffer ? GL_BACK : GL_FRONT;
viewer-getCamera()-setDrawBuffer(buffer);
viewer-getCamera()-setReadBuffer(buffer);

viewer-getCamera()-setRenderTargetImplementation(::osg::CameraNode::FRAME_BUFFER_OBJECT);

viewer-frame();

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Re: [osg-users] How to render the OSG scene to an image file?

[Igor Galochkin]

Thanks a lot for you replies! I tried to use the code but so far without 
success. At most I get a completely black image, but sometimes the 
SnapImageDrawcallback's operator() is never even called..

Here is my code. What exactly am I doing wrong here?

class SnapImageDrawCallback : public 
::osg::CameraNode::DrawCallback 
{ 
public: 

SnapImageDrawCallback() 
{ 
_snapImageOnNextFrame = false; 
} 

void setFileName(const std::string filename) { 
_filename = filename; } 
const std::string getFileName() const { return 
_filename; } 

void setSnapImageOnNextFrame(bool flag) { 
_snapImageOnNextFrame = flag; } 
bool getSnapImageOnNextFrame() const { return 
_snapImageOnNextFrame; } 

virtual void operator () (const 
::osg::CameraNode camera) const 
{ 
::osg::notify(::osg::NOTICE)  Saving 
screen image to '_filename' std::endl; 
if (!_snapImageOnNextFrame) return; 

int x,y,width,height; 
x = camera.getViewport()-x(); 
y = camera.getViewport()-y(); 
width = camera.getViewport()-width(); 
height = 
camera.getViewport()-height(); 

::osg::ref_ptr ::osg::Image image = 
new ::osg::Image(); 

image-readPixels(x,y,width,height,GL_RGB,GL_UNSIGNED_BYTE); 

if 
(::osgDB::writeImageFile(*image,_filename)) 
{ 
std::cout  Saved screen 
image to '_filename' std::endl; 
} 

_snapImageOnNextFrame = false; 
} 

protected: 

::std::string _filename; 
mutable bool _snapImageOnNextFrame; 


}; 


void 
renderSceneToImage(::osg::Node* pRoot, const 
::std::string sFileName_)
{
int nWidth = 640, nHeight = 480;

::osgViewer::Viewer * viewer = new 
::osgViewer::Viewer();
viewer-setSceneData(pRoot);

viewer-getCamera()-setRenderTargetImplementation(::osg::CameraNode::FRAME_BUFFER_OBJECT);

::osg::ref_ptrSnapImageDrawCallback 
snapImageDrawCallback = new SnapImageDrawCallback(); 
viewer-getCamera()-setPostDrawCallback 
(snapImageDrawCallback.get()); 

snapImageDrawCallback-setFileName(sFileName_); 

snapImageDrawCallback-setSnapImageOnNextFrame(true); 


::osg::ref_ptr ::osg::GraphicsContext pbuffer;

::osg::ref_ptr ::osg::GraphicsContext::Traits 
traits = new ::osg::GraphicsContext::Traits;
traits-x = 0;
traits-y = 0;
traits-width = nWidth;
traits-height = nHeight;
traits-red = 8;
traits-green = 8;
traits-blue = 8;
traits-alpha = 8;
traits-windowDecoration = false;
traits-pbuffer = true;
traits-doubleBuffer = true;
traits-sharedContext = 0;

pbuffer = 
::osg::GraphicsContext::createGraphicsContext(traits.get());
if (pbuffer.valid())
{ 
::osg::ref_ptr ::osg::Camera camera2 
= new ::osg::Camera();

camera2-setGraphicsContext(pbuffer.get());
GLenum buffer = 
pbuffer-getTraits()-doubleBuffer ? GL_BACK : GL_FRONT;
camera2-setDrawBuffer(buffer);
 

[osg-users] How to render the OSG scene to an image file?

[Igor Galochkin]

I have to write a series of classes wrapping OSG model, which loads OSG graph 
from an .osg file, uses some data from it, saves the scene back to .osg file 
etc.

I can't find out how (if it's possible) to render an OSG graph into an image 
file. 

So, what i am trying to do is:

void renderSceneToImage(::osg::Node* pNode, const ::std::string sFileName_, 
some camera parameteres here)

The function should take the root node of the OSG scene, render it ONCE to an 
image (::osg::Image?) and then save the image into the file.

I don't need to open any windows.

From what I found on the net so far:

//

::osg::Image* capImage = new ::osg::Image();
capImage-allocateImage(nWidth, nHeight, 1, GL_RGBA, GL_FLOAT);
capImage-setInternalTextureFormat(GL_RGBA16F_ARB);


::osg::ref_ptr ::osg::Camera camera = new ::osg::Camera();
camera-setRenderTargetImplementation(::osg::CameraNode::FRAME_BUFFER_OBJECT);
camera-setRenderOrder(::osg::Camera::PRE_RENDER);
camera-setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
camera-setViewport(0, 0, nWidth, nHeight);

camera-attach(::osg::CameraNode::COLOR_BUFFER, capImage);

// temporarily wrap the whole scene with camera
camera-addChild(pScene-root());

::osg::ref_ptr ::osg::Group tempRoot = new ::osg::Group();
tempRoot-addChild(camera.get()); 


// HOW TO ORDER THE CAMERA TO RENDER?

::osgDB::writeImageFile(*capImage, sFileName_);

//-

So, i can't find any way to order the camera to render once. All examples show 
how to make the camera render to a texture, but when it renders is decided by 
OpenGL (?). I don't need all that, i just need to grab the picture once and 
return.

Is this possible with OSG?

Thanks!

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