Hi Robert,
Robert O wrote:
> Dear All!
>
> I have a simple scene with a single geometry and material loaded from a VRML
> file
> with the SceneFileHandler class.
> I want to chnage the transparency of the object with the
> MakeTransparentGraphOp class, but unfortunatly it doesn't work
> properly for transparency values > 0 and < 1.
> (This issue has been discussed before Vol 6, Issue 47 Msg:2, without a
> solution).
> I use OpenSG 1.8.
>
> MakeTransparentGraphOp *op = new MakeTransparentGraphOp();
> float alpha = 0.5;
> std::ostringstream str;
> str << "transparency=" << alpha;
> op->setParams ( str.str() );
> graphOperator->addGraphOp(op);
>
> Could anyone give some hints, how to solve this problem
hm, for me it seems to work, I just used the testSingleOp test program
(Source/System/GraphOp/testSingleOp.cpp) to make a semi-transparent tie
model (Tutorial/Data/tie.wrl).
I called the test program like this:
./testSingleOp MakeTransparent transparency=0.5 tie.wrl tie.trans.osb
Loading the model with, e.g. testNavigator tie.trans.osb gives me
translucent tie. Could you please compare your code with the
testSingleOp program to see if there is any difference ?
> and how to
> change the sorting sequnce within a single node to get rid if the
> artefacts.
Now that is a more difficult problem which in general would require at
least polygon level depth sorting of the transparent polygons. OpenSG
does not do this, as it would be extremely slow, but depending on your
needs you can often get away with using a different blend function. If
you use one that is independent of the destination fragments the
transparency might not look as nice, but it becomes independent of the
rendering order.
Hope it helps,
Carsten
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