I changed the last bit of code to this:
osg::TexEnv* texEnv = new osg::TexEnv();
texEnv->setMode( osg::TexEnv::ADD );
ss->setMode(GL_BLEND,osg::StateAttribute::ON);
ss->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
ss->setTextureAttribute( 0, texEnv );
geometry->setStateSet( ss );
osg::Vec4Array* color = new osg::Vec4Array;
color->push_back( osg::Vec4f( 1, 1, 1, 0 ) );
geometry->setColorArray( color );
geometry->setColorBinding( osg::Geometry::BIND_OVERALL );
Now I have the basic effect of not having the background show up. I need to
figure out how to tweak some things to get the text to be a bit clearer. I'm
also not sure if my "solution" is the correct one, or if I just stumbled onto
something that works for now. I'm not sure what TRANSPARENT_BIN translates
to in OpenGL terms.
I guess RTFS is always an answer.
On Monday 30 October 2006 18:48, Steven T. Hatton wrote:
> I created a class intended to act as a floating label for components within
> the scene. I would use the osg text library except that many of my labels
> use sophisticated mathematical expressions which would be difficult to lay
> out. What I do is generate my text using Mathematica, and then run it
> through some code using Magick++ to clear the background. The code below
> is what I am using to create the label in the scene.
>
> When I use it, the labels appear with a white background. Using
> osg::TexEnv::DECAL seems to let the color bound to the QUAD show through,
> but what I really want is for the background part to be transparent so that
> the rest of the scene shows through. Can that be accomplished? How?
>
> class ComponentLabel : public osg::MatrixTransform {
> //...
> ComponentLabel( const std::string& fileName = "fileName_not_given")
> this->setMatrix( osg::Matrix::translate( vec3f( from ) ) );
> osg::AutoTransform * ax = new osg::AutoTransform();
>
> ax->setAutoRotateMode( osg::AutoTransform::ROTATE_TO_CAMERA );
> this->addChild( ax );
>
> osg::Geode* g = new osg::Geode();
> g->addDrawable( _edge_rptr.get() );
> this->addChild( g );
>
> ax->setPosition( vec3f( to ) );
>
> osg::Geode * geode = new osg::Geode();
> ax->addChild( geode );
>
> osg::Geometry* geometry = new osg::Geometry();
> geode->addDrawable( geometry );
>
> osg::DrawElementsUInt* face = new osg::DrawElementsUInt(
> osg::PrimitiveSet::QUADS, 0 );
> geometry->addPrimitiveSet( face );
> face->push_back( 0 );
> face->push_back( 1 );
> face->push_back( 2 );
> face->push_back( 3 );
>
>
> osg::Image * image = osgDB::readImageFile( fileName );
> if ( !image ) {
> std::cerr << "diagram::ComponentLabel(): failed to load file -> " <<
> fileName << std::endl;
> return ;
> }
>
> image->setFileName( fileName );
>
> osg::Texture2D* texture = new osg::Texture2D();
> texture->setImage( 0, image );
>
> osg::Vec3Array* vertices = new osg::Vec3Array;
> geometry->setVertexArray( vertices );
> osg::Vec3 dw( image->s()/2, 0, 0 );
> osg::Vec3 dh( 0, image->t()/2, 0 );
>
> dw*=0.001f;
> dh*=0.001f;
> vertices->push_back( -( dw + dh ) );
> vertices->push_back( dw - dh );
> vertices->push_back( dw + dh );
> vertices->push_back( -dw + dh );
>
>
> osg::Vec2Array* texcoords = new osg::Vec2Array( 4 );
> ( *texcoords ) [ 0 ].set( 0.0f, 0.0f );
> ( *texcoords ) [ 1 ].set( 1.0f, 0.0f );
> ( *texcoords ) [ 2 ].set( 1.0f, 1.0f );
> ( *texcoords ) [ 3 ].set( 0.0f, 1.0f );
>
> geometry->setTexCoordArray( 0, texcoords );
>
> osg::StateSet* ss = geode->getOrCreateStateSet();
> ss->setTextureAttributeAndModes( 0, texture, osg::StateAttribute::ON );
>
> osg::TexEnv* texEnv = new osg::TexEnv();
> texEnv->setMode( osg::TexEnv::REPLACE );
> ss->setTextureAttribute( 0, texEnv );
> geometry->setStateSet( ss );
>
> osg::Vec4Array* color = new osg::Vec4Array;
> color->push_back( osg::Vec4f( 0, 0, 0, 1 ) );
> geometry->setColorArray( color );
> geometry->setColorBinding( osg::Geometry::BIND_OVERALL );
>
> }
> };
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