[osg-users] Transparency on a drawable
Paul Speed
pspeed at progeeks.com
Tue Jul 15 01:03:13 PDT 2008
Vincent Bourdier wrote:
> Hi
>
> Yes, no solutions seems to work on my problem.
> Because all the propositions concern nodes, I permit to remember that I
> am looking at a way to set alpha level on a osg::Geometry ...
>
> On node I already have a method using material : set alpha channel, and
> it works good... But on my geometry nothing look to work good...
>
> This is all my geometry creator code :
>
> osg::ref_ptr<osg::Geometry> builtGeometry(){
>
> double alpha = 0.1;
> osg::Vec4 grey(0.4,0.4,0.4,1.0);
> osg::Vec4 yellow(1.0,1.0,0.0,1.0);
What happens if you put alpha for the fourth value in your color?
-Paul
>
> osg::Geometry* g = new osg::Geometry;
> osg::Vec3Array* vertices = new osg::Vec3Array();
> osg::Vec3Array* normals = new osg::Vec3Array();
> osg::Vec4Array* colors = new osg::Vec4Array();
>
> normals->push_back(osg::Vec3(0,0,1));
> colors->push_back(grey);
>
> //----
> //QUAD
> vertices->push_back(osg::Vec3( _width/2.0, _height + _dist,
> _offset));
> vertices->push_back(osg::Vec3(-_width/2.0, _height + _dist,
> _offset));
> vertices->push_back(osg::Vec3(-_width/2.0, 0.0 + _dist,
> _offset));
> vertices->push_back(osg::Vec3( _width/2.0, 0.0 + _dist,
> _offset));
>
> if(!_empty)
> g->addPrimitiveSet(new
> osg::DrawArrays(osg::PrimitiveSet::QUADS,0,4));
> else
> g->addPrimitiveSet(new
> osg::DrawArrays(osg::PrimitiveSet::LINE_LOOP,0,4));
>
>
> //-----
> //LINE
>
> vertices->push_back(osg::Vec3(0.0, 1.0, _offset));
> vertices->push_back(osg::Vec3(0.0, _dist, _offset));
> colors->push_back(grey);
> g->addPrimitiveSet(new
> osg::DrawArrays(osg::PrimitiveSet::LINES,4,2));
>
>
> //----
> //LINE_LOOP
>
> vertices->push_back(osg::Vec3( _width/2.0, _height + _dist,
> _offset/2.0));
> vertices->push_back(osg::Vec3(-_width/2.0, _height + _dist,
> _offset/2.0));
> vertices->push_back(osg::Vec3(-_width/2.0, 0.0 + _dist,
> _offset/2.0));
> vertices->push_back(osg::Vec3( _width/2.0, 0.0 + _dist,
> _offset/2.0));
>
> colors->push_back(yellow);
> g->addPrimitiveSet(new
> osg::DrawArrays(osg::PrimitiveSet::LINE_LOOP,6,4));
>
> g->setNormalArray(normals);
> g->setVertexArray(vertices);
> g->setColorArray(colors);
>
> g->setNormalBinding(osg::Geometry::BIND_OVERALL);
> g->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE_SET);
> g->setDataVariance(osg::Object::DYNAMIC);
>
>
> //TRANSPARENCY
>
> osg::StateSet* state = g->getOrCreateStateSet();
>
> state->setMode(GL_BLEND,osg::StateAttribute::ON|osg::StateAttribute::OVERRIDE);
> osg::Material* mat = new osg::Material;
> mat->setAlpha(osg::Material::FRONT_AND_BACK, alpha);
> state->setAttributeAndModes(mat,osg::StateAttribute::ON |
> osg::StateAttribute::OVERRIDE);
>
> osg::BlendFunc* bf = new
> osg::BlendFunc(osg::BlendFunc::SRC_ALPHA,
> osg::BlendFunc::ONE_MINUS_SRC_ALPHA );
> state->setAttributeAndModes(bf);
>
> state->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
> state->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
>
> g->setStateSet(state);
>
> return g;
> }
>
>
> Thanks for your help.
>
> Regards,
>
> Vincent.
>
> 2008/7/15 dimi christop <dimi_christop at yahoo.com
> <mailto:dimi_christop at yahoo.com>>:
>
> Hi Vincent,
> I see you still havent found a solution. So here I send you a
> complete example of transpareny.
> Its a modification of the Viewer example from the Qucik start guide.
> It loads up a cow and overrides the alpha to 0.1.
> Hope you can start from there.
>
> Dimi
>
> // Viewer Example, A minimal OSG viewer
> #include <osgDB/WriteFile>
> #include <osg/Notify>
> #include <osgViewer/Viewer>
> #include <osgDB/ReadFile>
> #include <osg/MatrixTransform>
> #include <osg/Geode>
> #include <osg/Geometry>
> #include <osg/StateSet>
> #include <osg/StateAttribute>
> #include <osg/CullFace>
> #include <osg/Point>
> #include <osg/Light>
> #include <osg/LightSource>
> #include <osg/BlendFunc>
> #include <osg/Material>
> #include <osg/PolygonMode>
> #include <osg/Notify>
>
> int
> main( int, char ** )
> {
> // Create a Viewer.
> osgViewer::Viewer viewer;
>
> // Load a model and add it to the Viewer.
> osg::ref_ptr<osg::Node> nde = osgDB::readNodeFile( "cow.osg" );
>
> // Create StateSet and Material
> osg::StateSet* state2 = nde->getOrCreateStateSet();
> osg::ref_ptr<osg::Material> mat2 = new osg::Material;
>
> // Set alpha to 0.1
> mat2->setAlpha(osg::Material::FRONT_AND_BACK, 0.1);
> state2->setAttributeAndModes( mat2.get() ,
> osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);
>
> // Turn on blending
> osg::BlendFunc* bf = new
> osg::BlendFunc(osg::BlendFunc::SRC_ALPHA,
> osg::BlendFunc::ONE_MINUS_SRC_ALPHA );
> state2->setAttributeAndModes(bf);
>
> viewer.setSceneData(nde.get());
>
> if (!viewer.getSceneData())
> {
> osg::notify( osg::FATAL ) << "Unable to load data file.
> Exiting." << std::endl;
> return 1;
> }
>
> // Display, and main loop.
> return viewer.run();
> }
>
> ----- Original Message ----
> From: Vincent Bourdier <vincent.bourdier at gmail.com
> <mailto:vincent.bourdier at gmail.com>>
> To: OpenSceneGraph Users <osg-users at lists.openscenegraph.org
> <mailto:osg-users at lists.openscenegraph.org>>
> Sent: Tuesday, July 15, 2008 9:04:23 AM
> Subject: Re: [osg-users] Transparency on a drawable
>
> Hi Ulrich
>
> thanks for help.
>
> I use/try this code for the moment :
>
> osg::StateSet* state = g->getOrCreateStateSet();
>
> state->setMode(GL_BLEND,osg::StateAttribute::ON|osg::StateAttribute::OVERRIDE);
> osg::Material* mat =
> (osg::Material*)state->getAttribute(osg::StateAttribute::MATERIAL);
> if(!mat) {
> mat = new osg::Material;
> }
> mat->setAlpha(osg::Material::FRONT_AND_BACK, alpha);
> state->setAttributeAndModes(mat,osg::StateAttribute::ON);
> state->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
> state->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
>
> But nothing appear transparent...
>
> Regards,
> Vincent
>
> 2008/7/12 Ulrich Hertlein <u.hertlein at sandbox.de
> <mailto:u.hertlein at sandbox.de>>:
>
> Vincent Bourdier wrote:
>
> I do exactly the same things, on Nodes...
>
> stateset->setMode(GL_BLEND,
> osg::StateAttribute::OVERRIDE | osg::StateAttribute::ON );
>
> stateset->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
>
>
> Are you sure you're doing this last line? It's not in the code
> snippet you posted initially...
>
> Cheers,
> /ulrich
>
>
> double opacity = 0.1;
>
> osg::StateSet* state = mygometry->getOrCreateStateSet();
> state->setMode(GL_BLEND,osg::StateAttribute::ON|
> osg::StateAttribute::OVERRIDE);
> osg::Material* mat = (osg::Material*)state->getAttribute
> (osg::StateAttribute::MATERIAL);
> if(!mat) {
> mat = new osg::Material;
> mat->setAlpha(osg::Material::FRONT_AND_BACK, opacity);
>
> state->setAttributeAndModes(mat,osg::StateAttribute::ON);
> }
>
>
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