Hi everyone,
I am trying to get screenshots of a generated scene with OSG. In order to do
that I am using the method readPixels of the class osg::image. But it seems
that the function glReadPixels used by readPixels fails. Here is a part of
the code:
//start the rendering
float * depthBufferRaw;
osg::Image * depthBuffer= new osg::Image();
unsigned char * tmp;
int height=1280;
int width=1024;
int i;
depthBufferRaw = (float *) calloc(height*width, sizeof(float));
while(!viewer->done())
{
viewer->frame();
//Get values of the color buffer
depthBuffer->readPixels(0,0,width,height,
GL_LUMINANCE,GL_UNSIGNED_BYTE);
tmp = depthBuffer->data();
for (i=0; i<height*width; i++)
depthBufferRaw[i]=(float) tmp[i];
//save as image
...
}
With the above code, i get an array (depthBufferRaw) with constant values
whereas i see on my screen a scene with different objects and colors. Thanks
to debug mode of VS2003, i can verify that depthBuffer->_data has been
allocated.
The source code of the osg::image method readPixels is the following:
void Image::readPixels(int x,int y,int width,int height,GLenum format,GLenum
type)
{
allocateImage(width,height,1,format,type);
glPixelStorei(GL_PACK_ALIGNMENT,_packing);
glReadPixels(x,y,width,height,format,type,_data);
}
So, it seems that glReadPixels failed. I tried to show this by using
directly glReadPixels in my implementation with glGetError.
Strangely glGetError returns the value 1282 (GL_INVALID_OPERATION)
whatever the position of the call to this function in my code. And when i
tried to use this function in a loop as :
while (errCode != GL_NO_ERROR)
errCode = glGetError();
I obtain an infinite loop.
My questions are the following:
-Is that possible to use glGetError with OSG?
-Has anybody an idea of why the method readPixels fails in this case?
Thanks in advance!
Jean-Baptiste
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