[osg-users] [Problem with osgLight]

[Jean-Baptiste Authesserre]

Hi,

I am a little confused. My camera

2008/6/18 Paul Melis <paul at science.uva.nl>:

> Jean-Baptiste Authesserre wrote:
>
>> Hi everyone,
>>
>> I have some problem with OSG Light, and I don't find answer in the osg
>> archives. My problem is the following : I don't understand why with the
>> following code my object isn't uniformly enlighten. (cf. image in attached
>> document)
>> -The black and white square of the image is centered at (0, 0, 0) (in
>> world frame with convention (x, y, z))
>> -The camera is located at (0, 0, -20)
>> -the light is located at (0,20, -15)
>>
> If you didn't change this yourself then +Z will be the up axis, btw
>
>>
>>
>> The code for activating light is the following:
>>
>> /*****************************
>> ** light *************************************/
>>
>>
>>    //Creation of light source
>>    osg::Light* light = new osg::Light();
>>    osg::LightSource * lightsource = new osg::LightSource();
>>    lightsource->setLight(light);
>>    // put the light source in the scenegraph
>>    root->addChild(lightsource);
>>
>>    // turn light on
>>    osg::StateSet * stateset = root->getOrCreateStateSet();
>>    lightsource->setStateSetModes(*stateset, osg::StateAttribute::ON);
>>    light->setAmbient(osg::Vec4d(1.0, 1.0, 1.0, 1.0));
>>    //light->setDiffuse(osg::Vec4d(0.0, 0.0, 0.0, 0.0));
>>    //light->setSpecular(osg::Vec4d(1.0, 1.0, 1.0, 1.0));
>>    light->setPosition(osg::Vec4d(0.0, 20.0, -15.0, 1.0));
>>
>>
>> /******************************************************************************/
>>
>> So, I don't understand why the bottom-left corner of my square is darker
>> than the others corners
>>
> I don't see any difference here between left and right bottom corners,
> they're equally dark IMHO. Which seems to make sense, as you've put the
> light source above and little in front of the camera, but in the center of
> the object (the X plane).
>
> Paul
>
>> Has anybody an Idea?
>>
>>
>> Best regards,
>>
>> Jean-Baptiste.
>> ------------------------------------------------------------------------
>>
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>>
>
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