The fix was to check whether glGetString( GL_VERSION ) returned a null pointer (Ref. svn diff below). The altered src/osg/GLExtensions.cpp is zipped and attached to this email."
"Soft shadow mapping is basically the same as hard shadow mapping beside that
it uses a different fragment shader.
So for me it makes sense that osgShadow::SoftShadowMap is derived from
osgShadow::ShadowMap, this makes it easier to maintain the two classes.
Additional SoftShadowMap also provides the same Debug methods as ShadowMap."
I think I may have discovered a bug in osgShadow/ShadowMap.cpp that results in incomplete shadows being generated.
The problem seems to caused by an incorrect interpretation of the spot light cutoff angle. The valid ranges for spot cutoff are 0-90 and 180, i.e half the 'field of view' for the spotlight. Whereas the shadow map code seems to assume the the spot cutoff is equal to the field of view. This results in the shadows generated by the spotlight getting clipped at half the spot cutoff angle.
I have fixed this in my copy of ShadowMap.cpp:
===============================
//Original code from OSG 2.6:
if(selectLight->getSpotCutoff() < 180.0f) // spotlight, then we don't need the bounding box
{
osg::Vec3 position(lightpos.x(), lightpos.y(), lightpos.z());
float spotAngle = selectLight->getSpotCutoff();
_camera->setProjectionMatrixAsPerspective(spotAngle, 1.0, 0.1, 1000.0);
_camera->setViewMatrixAsLookAt(position,position+lightDir,osg::Vec3(0.0f,1.0f,0.0f));
}
===============================
// My modifications:
float fov = selectLight->getSpotCutoff() * 2;
if(fov < 180.0f) // spotlight, then we don't need the bounding box
{
osg::Vec3 position(lightpos.x(), lightpos.y(), lightpos.z());
_camera->setProjectionMatrixAsPerspective(fov, 1.0, 0.1, 1000.0);
_camera->setViewMatrixAsLookAt(position,position+lightDir,osg::Vec3(0.0f,1.0f,0.0f));
}
This change seems correct for spot cutoff in the range 0, 90, but since OpenGL doesn't claim to support cutoffs >90 && <180, I'm not sure how shadow map should deal with those cases, but ignoring spot cut off greater than 90 here seems reasonable to me.
"
> Using QOSGWidget - QWidget + osgViewer creating the graphics context.
>
> Windows Error #2000: [Screen #0] GraphicsWindowWin32::setWindow() - Unable
> to create OpenGL rendering context. Reason: The pixel format is invalid.
>
>
>
> And then the following fate error pops up:
>
>
>
> The instruction at "0x014c7ef1" referenced memory at "0x000000a4", The
> memory could not be "read".
>
> Click on Ok to terminate the program
>
> Click on CANCEL to debug the program
>
>
- adds display of options when using osgconv --formats.
- adds useGroupPerFeature option to have each feature in a separate group. Usage: OSG_OPTIMIZER=OFF osgconv -e ogr -O addGroupPerFeature <infile> <outfile>
"
