Re: [osg-users] multipass transparency

2012-10-10 Thread Sergey Polischuk 
Hi

For such complex transparent models you need some proper order-independent 
transparency algorithm

Cheers.

09.10.2012, 23:22, Tina Guo guoyiting1...@gmail.com:
 Hi,

 Thanks for reply. Now the code is like

 virtual void define_passes()
 {
 osg::ref_ptrosg::StateSet ss = new osg::StateSet;
 ss-setAttributeAndModes( new osg::ColorMask(true, true, true, true) 
 );
 osg::Depth* depth = new osg::Depth;
 depth-setWriteMask( false );
 ss-setAttributeAndModes( depth, osg::StateAttribute::ON );
 addPass( ss.get() );

 ss = new osg::StateSet;
 ss-setAttributeAndModes( new osg::ColorMask(false, false, 
 false, false) );
 depth-setWriteMask( true );
 ss-setAttributeAndModes( depth, osg::StateAttribute::ON );
 addPass( ss.get() );
 }

 However, it could not handle sel-intersection(the picture in the attached doc)

 Using:
 transparency-setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
 transparency-setAttributeAndModes(new osg::BlendFunc(GL_SRC_ALPHA 
 ,GL_ONE_MINUS_SRC_ALPHA), osg::StateAttribute:ShockedN);
 osg::Depth* depth = new osg::Depth;
 depth-setWriteMask( false );
 transparency-setAttributeAndModes( depth, osg::StateAttribute::ON );
 _geom_solid-setStateSet(transparency);

 instead of

 transparency-setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
 transparency-setAttributeAndModes(new osg::BlendFunc(GL_SRC_ALPHA 
 ,GL_ONE_MINUS_SRC_ALPHA), osg::StateAttribute:ShockedN);
 _geom_solid-setStateSet(transparency);

 self-intersection is correct. However, some transparent parts will disappear, 
 like the wheels of the car in the picture in the doc, the color seems to be 
 blended after the inner parts.

 ...

 Thank you!

 Cheers,
 Tina[/img]

 --
 Read this topic online here:
 http://forum.openscenegraph.org/viewtopic.php?p=50533#50533

 Attachments:
 http://forum.openscenegraph.org//files/test_152.pdf

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Re: [osg-users] multipass transparency

2012-10-09 Thread Sergey Polischuk 
Hi

If you need to blend all visible layers - try to change order of passes, and 
set colormask to all false's (so first will be only color, second only depth). 
If you dont need depth from transparent geometry - you can get by with only 
first pass.
If you need only closest single layer - you draw first pass depth only (with 
colormask set to false's), second pass with depth test set to lequal.

Cheers.

09.10.2012, 09:33, Tina Guo guoyiting1...@gmail.com:
 Hi,

 In open inventor, there is a transparency mode called: delayed blend

 Transparent objects are rendered using multiplicative alpha blending, in a 
 second rendering pass with depth buffer updates disabled. And I want to get 
 the same effect.

 here's what I am trying to do

 transparency-setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
 transparency-setAttributeAndModes(new osg::BlendFunc(GL_SRC_ALPHA 
 ,GL_ONE_MINUS_SRC_ALPHA), osg::StateAttribute::ON);
 _geom_solid-setStateSet(transparency);

 class TransparencyTechnique : public osgFX::Technique
 {
 public:
 TransparencyTechnique() : osgFX::Technique() {}
 virtual bool validate( osg::State ss ) const { return true; }

 protected:
 virtual void define_passes()
 {
 osg::ref_ptrosg::StateSet ss = new osg::StateSet;
 ss-setAttributeAndModes( new osg::ColorMask(true, true, true, true) 
 );
 addPass( ss.get() );

 ss = new osg::StateSet;
 osg::Depth* depth = new osg::Depth;
 depth-setWriteMask( false );
 ss-setAttributeAndModes( depth, osg::StateAttribute::ON );
 addPass( ss.get() );
 }
 };

 The result is not right. how should define_passes() be defined?

 ...

 Thank you!

 Cheers,
 Tina

 --
 Read this topic online here:
 http://forum.openscenegraph.org/viewtopic.php?p=50484#50484

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 osg-users@lists.openscenegraph.org
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Re: [osg-users] multipass transparency

2012-10-09 Thread Tina Guo 
Hi,

Thanks for reply. Now the code is like

virtual void define_passes()
{
osg::ref_ptrosg::StateSet ss = new osg::StateSet;
ss-setAttributeAndModes( new osg::ColorMask(true, true, true, true) );
osg::Depth* depth = new osg::Depth;
depth-setWriteMask( false );
ss-setAttributeAndModes( depth, osg::StateAttribute::ON );
addPass( ss.get() );


ss = new osg::StateSet;
ss-setAttributeAndModes( new osg::ColorMask(false, false, 
false, false) );
depth-setWriteMask( true );
ss-setAttributeAndModes( depth, osg::StateAttribute::ON );
addPass( ss.get() );
}

However, it could not handle sel-intersection(the picture in the attached doc)

Using: 
transparency-setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
transparency-setAttributeAndModes(new osg::BlendFunc(GL_SRC_ALPHA 
,GL_ONE_MINUS_SRC_ALPHA), osg::StateAttribute:ShockedN);
osg::Depth* depth = new osg::Depth;
depth-setWriteMask( false );
transparency-setAttributeAndModes( depth, osg::StateAttribute::ON );
_geom_solid-setStateSet(transparency); 

instead of 

transparency-setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
transparency-setAttributeAndModes(new osg::BlendFunc(GL_SRC_ALPHA 
,GL_ONE_MINUS_SRC_ALPHA), osg::StateAttribute:ShockedN);
_geom_solid-setStateSet(transparency); 

self-intersection is correct. However, some transparent parts will disappear, 
like the wheels of the car in the picture in the doc, the color seems to be 
blended after the inner parts. 

... 

Thank you!

Cheers,
Tina[/img]

--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=50533#50533




Attachments: 
http://forum.openscenegraph.org//files/test_152.pdf


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[osg-users] multipass transparency

2012-10-08 Thread Tina Guo 
Hi,

In open inventor, there is a transparency mode called: delayed blend

Transparent objects are rendered using multiplicative alpha blending, in a 
second rendering pass with depth buffer updates disabled. And I want to get the 
same effect.

here's what I am trying to do

transparency-setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
transparency-setAttributeAndModes(new osg::BlendFunc(GL_SRC_ALPHA 
,GL_ONE_MINUS_SRC_ALPHA), osg::StateAttribute::ON);
_geom_solid-setStateSet(transparency);



class TransparencyTechnique : public osgFX::Technique
{
public:
TransparencyTechnique() : osgFX::Technique() {}
virtual bool validate( osg::State ss ) const { return true; }

protected:
virtual void define_passes()
{
osg::ref_ptrosg::StateSet ss = new osg::StateSet;
ss-setAttributeAndModes( new osg::ColorMask(true, true, true, true) );
addPass( ss.get() );

ss = new osg::StateSet;
osg::Depth* depth = new osg::Depth;
depth-setWriteMask( false );
ss-setAttributeAndModes( depth, osg::StateAttribute::ON );
addPass( ss.get() );
}
};


The result is not right. how should define_passes() be defined?

... 

Thank you!

Cheers,
Tina

--
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=50484#50484





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