Re: [Flightgear-devel] PolygonOffset implementation

Fernando García Mon, 31 Oct 2011 15:03:49 -0700

Hi,

I just modified the Effects.cxx file in Simgear > simgear > scene >material. I changed a bit the code, and it succesfully doesn't give anyerrors now, but there isn't any visible results. Here is the new code:


struct PolygonOffsetBuilder : public PassAttributeBuilder
{

void buildAttribute(Effect* effect, Pass* pass, constSGPropertyNode* prop,

                        const SGReaderWriterXMLOptions* options)
    {
        if (!isAttributeActive(effect, prop))
            return;

        const SGPropertyNode* factor
           = getEffectPropertyChild(effect, prop, "factor");
        const SGPropertyNode* units
           = getEffectPropertyChild(effect, prop, "units");

        ref_ptr<PolygonOffset> polyoffset = new PolygonOffset;

        polyoffset->setFactor(factor->getFloatValue());
        polyoffset->setUnits(units->getFloatValue());

        pass->setAttributeAndModes(polyoffset.get(),

StateAttribute::OVERRIDE|StateAttribute::ON);

    }
};

InstallAttributeBuilder<PolygonOffsetBuilder>installPolygonOffset("polygon-offset");

I don't see anything wrong with the code, and I think it matches the OSGPolygonOffset class:http://www.openscenegraph.org/documentation/OpenSceneGraphReferenceDocs/a00523.html.


Cheers and thanks.

On 31/10/11 21:43, Frederic Bouvier wrote:

Hi,

it's difficult to answer questions like this. If you can post thefiles you modified, one of us could compile it and see what's going on.

Regards,
-Fred

------------------------------------------------------------------------

    Hello,

    This is my first try with mailing-list, I am icecode in IRC,
    Icecode GL in forum and a few time ago I've been involved in
    trying to return shadows back in FlightGear, exploring the big
    world of shaders and effects. But when Z-fighting
    (http://en.wikipedia.org/wiki/Z-fighting) problem appeared, I
    needed glPolygonOffset
    (http://www.opengl.org/sdk/docs/man/xhtml/glPolygonOffset.xml).
    After reading the OSG documentation
    
(http://www.openscenegraph.org/documentation/OpenSceneGraphReferenceDocs/a00523.html),
    I got this code at Simgear's Effect.cxx:

        struct PolygonOffsetBuilder : public PassAttributeBuilder
        {
            void buildAttribute(Effect* effect, Pass* pass, const
        SGPropertyNode* prop,
                                const SGReaderWriterXMLOptions* options)
            {
                if (!isAttributeActive(effect, prop))
                    return;

                const SGPropertyNode* pfactor
                    = getEffectPropertyChild(effect, prop, "factor");
                const SGPropertyNode* punits
                    = getEffectPropertyChild(effect, prop, "units");

                ref_ptr<PolygonOffset> polyoffset = new PolygonOffset;

                int factor, units;

                if (pfactor)
                    factor = pfactor->getIntValue();
                if (punits)
                    units = punits->getIntValue();

                polyoffset->setFactor(factor);
                polyoffset->setUnits(units);

                pass->setAttributeAndModes(polyoffset.get());
            }
        };

        InstallAttributeBuilder<PolygonOffsetBuilder>
        installPolygonOffset("polygon-offset");


     I correctly did the #include <osg/PolygonOffset> at the start of
    file. Compilation goes OK, but when I run FG, this message appears
    a couple of times:

        skipping unknown pass attribute polygon-offset


     What can be the problem? Sorry if it is a silly mistake, but I am
    a newbie in the effects things etc. If you want to know anything
    more about the shadows, I am trying to implement the shadow
    volumes (http://en.wikipedia.org/wiki/Shadow_volume) technique,
    using stencil. Info of progress, .vert and .eff at forum topic:
    http://www.flightgear.org/forums/viewtopic.php?f=47&t=13648
    <http://www.flightgear.org/forums/viewtopic.php?f=47&t=13648>.

    Cheers.

    
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in minutes. BlackBerry App World&#153; now supports Android&#153; Apps
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it is! http://p.sf.net/sfu/android-dev2dev


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------------------------------------------------------------------------------
Get your Android app more play: Bring it to the BlackBerry PlayBook 
in minutes. BlackBerry App World&#153; now supports Android&#153; Apps 
for the BlackBerry&reg; PlayBook&#153;. Discover just how easy and simple 
it is! http://p.sf.net/sfu/android-dev2dev

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Re: [Flightgear-devel] PolygonOffset implementation

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