Thanks Chris, changes merged and submitted to SVN.
On Mon, Sep 15, 2008 at 3:44 PM, Chris Denham <[EMAIL PROTECTED]> wrote:
> Reposting to submissions list, and attached modified version of OSG2.6
> ShadowMap.cpp
> Cheers.
> Chris.
>
> ----- Original Message ----- From: "Chris Denham" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Monday, September 15, 2008 10:25 AM
> Subject: Bug in FOV calculation for Spotlights in 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.
>> Cheers.
>> Chris Denham
>>
>>
>>
>>
>>
>>
>
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