[osg-users] Resizing FBO camera while rendering

[RÃŽmulo Cerqueira]

Hi,

I have rendered a FBO camera to image by using a callback (as seen in the code below), however some OpenGL warnings/erros are raised when I resize at runtime by setupViewer() method. I debugged the code by using


Code:
export OSG_GL_ERROR_CHECKING=ON



and got the following error:


Code:
Warning: detected OpenGL error 'invalid operation' after applying attribute Viewport 0x7fb35406e500



How can I properly do the resizing of my FBO camera?



Code:
// create a RTT (render to texture) camera
osg::Camera *ImageViewerCaptureTool::createRTTCamera(osg::Camera* cam, osg::Camera::BufferComponent buffer, osg::Texture2D *tex, osg::GraphicsContext *gfxc)
{
osg::ref_ptr<osg::Camera> camera = cam;
camera->setClearColor(osg::Vec4(0, 0, 0, 1));
camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
camera->setRenderOrder(osg::Camera::PRE_RENDER, 0);
camera->setViewport(0, 0, tex->getTextureWidth(), tex->getTextureHeight());
camera->setGraphicsContext(gfxc);
camera->setDrawBuffer(GL_FRONT);
camera->setComputeNearFarMode(osg::CullSettings::DO_NOT_COMPUTE_NEAR_FAR);
camera->attach(buffer, tex);
return camera.release();
}

// create float textures to be rendered in FBO
osg::Texture2D* ImageViewerCaptureTool::createFloatTexture(uint width, uint height)
{
osg::ref_ptr<osg::Texture2D> tex2D = new osg::Texture2D;
tex2D->setTextureSize( width, height );
tex2D->setInternalFormat( GL_RGB32F_ARB );
tex2D->setSourceFormat( GL_RGBA );
tex2D->setSourceType( GL_FLOAT );
tex2D->setResizeNonPowerOfTwoHint( false );
tex2D->setFilter( osg::Texture2D::MIN_FILTER, osg::Texture2D::LINEAR );
tex2D->setFilter( osg::Texture2D::MAG_FILTER, osg::Texture2D::LINEAR );
return tex2D.release();
}

void ImageViewerCaptureTool::setupViewer(uint width, uint height, double fovY)
{
// set graphics contexts
osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
traits->x = 0;
traits->y = 0;
traits->width = width;
traits->height = height;
traits->pbuffer = true;
traits->readDISPLAY();
osg::ref_ptr<osg::GraphicsContext> gfxc = osg::GraphicsContext::createGraphicsContext(traits.get());

// set the main camera
_viewer = new osgViewer::Viewer;
osg::ref_ptr<osg::Texture2D> tex = createFloatTexture(width, height);
osg::ref_ptr<osg::Camera> cam = createRTTCamera(_viewer->getCamera(), osg::Camera::COLOR_BUFFER0, tex, gfxc);
cam->setProjectionMatrixAsPerspective(osg::RadiansToDegrees(fovY), (width * 1.0 / height), 0.1, 1000);

// render texture to image
_capture = new WindowCaptureScreen(gfxc, tex);
cam->setFinalDrawCallback(_capture);
}

osg::ref_ptr<osg::Image> ImageViewerCaptureTool::grabImage(osg::ref_ptr<osg::Node> node)
{
// set the current node
_viewer->setSceneData(node);

// if the view matrix is invalid (NaN), use the identity
if (_viewer->getCamera()->getViewMatrix().isNaN())
_viewer->getCamera()->setViewMatrix(osg::Matrixd::identity());

// grab the current frame
_viewer->frame();
return _capture->captureImage();
}

////////////////////////////////
////WindowCaptureScreen METHODS
////////////////////////////////

WindowCaptureScreen::WindowCaptureScreen(osg::ref_ptr<osg::GraphicsContext> gfxc, osg::Texture2D* tex) {
_mutex = new OpenThreads::Mutex();
_condition = new OpenThreads::Condition();
_image = new osg::Image();

// checks the GraficContext from the camera viewer
if (gfxc->getTraits()) {
_tex = tex;
int width = gfxc->getTraits()->width;
int height = gfxc->getTraits()->height;
_image->allocateImage(width, height, 1, GL_RGBA, GL_FLOAT);
}
}

WindowCaptureScreen::~WindowCaptureScreen() {
delete (_condition);
delete (_mutex);
}

osg::ref_ptr<osg::Image> WindowCaptureScreen::captureImage() {
//wait to finish the capture image in call back
_condition->wait(_mutex);
return _image;
}

void WindowCaptureScreen::operator ()(osg::RenderInfo& renderInfo) const {
osg::ref_ptr<osg::GraphicsContext> gfxc = renderInfo.getState()->getGraphicsContext();

if (gfxc->getTraits()) {
_mutex->lock();

// read the color buffer as 32-bit floating point
renderInfo.getState()->applyTextureAttribute(0, _tex);
_image->readImageFromCurrentTexture(renderInfo.getContextID(), true, GL_FLOAT);

// grants the access to image
_condition->signal();
_mutex->unlock();
}
}



...

Thanks in advance,

Cheers,
Rômulo

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=75005#75005

[Robert Osfield]

Hi Rômulo,

I didn't spot any code you posted that handles resizing, did I miss it?

Robert.
On Tue, 2 Oct 2018 at 08:10, Rômulo Cerqueira

Post by RÃŽmulo Cerqueira
Hi,
I have rendered a FBO camera to image by using a callback (as seen in the code below), however some OpenGL warnings/erros are raised when I resize at runtime by setupViewer() method. I debugged the code by using
export OSG_GL_ERROR_CHECKING=ON
Warning: detected OpenGL error 'invalid operation' after applying attribute Viewport 0x7fb35406e500
How can I properly do the resizing of my FBO camera?
// create a RTT (render to texture) camera
osg::Camera *ImageViewerCaptureTool::createRTTCamera(osg::Camera* cam, osg::Camera::BufferComponent buffer, osg::Texture2D *tex, osg::GraphicsContext *gfxc)
{
osg::ref_ptr<osg::Camera> camera = cam;
camera->setClearColor(osg::Vec4(0, 0, 0, 1));
camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
camera->setRenderOrder(osg::Camera::PRE_RENDER, 0);
camera->setViewport(0, 0, tex->getTextureWidth(), tex->getTextureHeight());
camera->setGraphicsContext(gfxc);
camera->setDrawBuffer(GL_FRONT);
camera->setComputeNearFarMode(osg::CullSettings::DO_NOT_COMPUTE_NEAR_FAR);
camera->attach(buffer, tex);
return camera.release();
}
// create float textures to be rendered in FBO
osg::Texture2D* ImageViewerCaptureTool::createFloatTexture(uint width, uint height)
{
osg::ref_ptr<osg::Texture2D> tex2D = new osg::Texture2D;
tex2D->setTextureSize( width, height );
tex2D->setInternalFormat( GL_RGB32F_ARB );
tex2D->setSourceFormat( GL_RGBA );
tex2D->setSourceType( GL_FLOAT );
tex2D->setResizeNonPowerOfTwoHint( false );
tex2D->setFilter( osg::Texture2D::MIN_FILTER, osg::Texture2D::LINEAR );
tex2D->setFilter( osg::Texture2D::MAG_FILTER, osg::Texture2D::LINEAR );
return tex2D.release();
}
void ImageViewerCaptureTool::setupViewer(uint width, uint height, double fovY)
{
// set graphics contexts
osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
traits->x = 0;
traits->y = 0;
traits->width = width;
traits->height = height;
traits->pbuffer = true;
traits->readDISPLAY();
osg::ref_ptr<osg::GraphicsContext> gfxc = osg::GraphicsContext::createGraphicsContext(traits.get());
// set the main camera
_viewer = new osgViewer::Viewer;
osg::ref_ptr<osg::Texture2D> tex = createFloatTexture(width, height);
osg::ref_ptr<osg::Camera> cam = createRTTCamera(_viewer->getCamera(), osg::Camera::COLOR_BUFFER0, tex, gfxc);
cam->setProjectionMatrixAsPerspective(osg::RadiansToDegrees(fovY), (width * 1.0 / height), 0.1, 1000);
// render texture to image
_capture = new WindowCaptureScreen(gfxc, tex);
cam->setFinalDrawCallback(_capture);
}
osg::ref_ptr<osg::Image> ImageViewerCaptureTool::grabImage(osg::ref_ptr<osg::Node> node)
{
// set the current node
_viewer->setSceneData(node);
// if the view matrix is invalid (NaN), use the identity
if (_viewer->getCamera()->getViewMatrix().isNaN())
_viewer->getCamera()->setViewMatrix(osg::Matrixd::identity());
// grab the current frame
_viewer->frame();
return _capture->captureImage();
}
////////////////////////////////
////WindowCaptureScreen METHODS
////////////////////////////////
WindowCaptureScreen::WindowCaptureScreen(osg::ref_ptr<osg::GraphicsContext> gfxc, osg::Texture2D* tex) {
_mutex = new OpenThreads::Mutex();
_condition = new OpenThreads::Condition();
_image = new osg::Image();
// checks the GraficContext from the camera viewer
if (gfxc->getTraits()) {
_tex = tex;
int width = gfxc->getTraits()->width;
int height = gfxc->getTraits()->height;
_image->allocateImage(width, height, 1, GL_RGBA, GL_FLOAT);
}
}
WindowCaptureScreen::~WindowCaptureScreen() {
delete (_condition);
delete (_mutex);
}
osg::ref_ptr<osg::Image> WindowCaptureScreen::captureImage() {
//wait to finish the capture image in call back
_condition->wait(_mutex);
return _image;
}
void WindowCaptureScreen::operator ()(osg::RenderInfo& renderInfo) const {
osg::ref_ptr<osg::GraphicsContext> gfxc = renderInfo.getState()->getGraphicsContext();
if (gfxc->getTraits()) {
_mutex->lock();
// read the color buffer as 32-bit floating point
renderInfo.getState()->applyTextureAttribute(0, _tex);
_image->readImageFromCurrentTexture(renderInfo.getContextID(), true, GL_FLOAT);
// grants the access to image
_condition->signal();
_mutex->unlock();
}
}
...
Thanks in advance,
Cheers,
Rômulo
------------------
http://forum.openscenegraph.org/viewtopic.php?p=75005#75005
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[RÃŽmulo Cerqueira]

Hi Robert,

I use the method setupViewer() "to resize" the FBO as well (by instantiating the viewer, camera, texture and callback again). This approach was the best way so far to minimize this problem.

...

Thank you!

Cheers,
Rômulo

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=75014#75014

[RÃŽmulo Cerqueira]

Hi Robert,

I use the method setupViewer() "to resize" the FBO as well (by instantiating the viewer, camera, texture and callback again). This approach was the best way so far to minimize this problem.

...

Thank you!

Cheers,
Rômulo

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=75016#75016

[Robert Osfield]

Hi Rômulo,

On Tue, 2 Oct 2018 at 18:45, Rômulo Cerqueira

Post by RÃŽmulo Cerqueira
I use the method setupViewer() "to resize" the FBO as well (by instantiating the viewer, camera, texture and callback again). This approach was the best way so far to minimize this problem.

What I was trying to work out is whether calling setupViewer() was
just done because of the FBO resize of whether it was being done for
other reasons as well.

As a general approach I'd recommend sticking with a single
GraphicsWindow where possible and just handling the resize of the FBO,
or at least the mapping of the resize in other ways. For instance one
approach you could take is to create a FBO in the maximum window size
then just use a viewport to select which part is active. Another
approach is to force a rebuild of the FBO by clearing the
RenderingCache via camera->setRenderingCache(0).

Robert.

[Robert Osfield]

Hi Rômulo,

On Tue, 2 Oct 2018 at 12:40, Rômulo Cerqueira

Post by RÃŽmulo Cerqueira
I use the method setupViewer() "to resize" the FBO as well (by instantiating the viewer, camera, texture and callback again). This approach was the best way so far to minimize this problem.

So you are setting a whole new graphics context and associated data on
each resize?

With this you are getting the GL error?

Robert.

[RÃŽmulo Cerqueira]

Hi,

Post by Robert Osfield
So you are setting a whole new graphics context and associated data on
each resize?

Yes, Robert.

...

Thank you!

Cheers,
Rômulo

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=75019#75019

[Robert Osfield]

On Tue, 2 Oct 2018 at 16:20, Rômulo Cerqueira

Post by Robert Osfield
So you are setting a whole new graphics context and associated data on
each resize?

Is it only the FBO that is forcing you to do this?

Robert.

[RÃŽmulo Cerqueira]

Post by Robert Osfield
Is it only the FBO that is forcing you to do this?

Yes.

Do you have any tip how can I solve this issue?

I found similar problems into links below, but I could not have the same success.

https://groups.google.com/forum/#!topic/osg-users/Oxb9QF8Myyo
https://groups.google.com/forum/#!topic/osg-users/ScUN5VSj6W8

------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=75025#75025

[Robert Osfield]

Hi Rômulo,

On Tue, 2 Oct 2018 at 22:10, Rômulo Cerqueira

Post by RÃŽmulo Cerqueira
Do you have any tip how can I solve this issue?

I haven't personally implemented what you are after so I provided tips
as to what direction to go in.

Robert.