Oups forget what I tell about my simpification as  "else path in  
DrawElementsXX::draw's if(ebo)" may only be reached when compiling 
DisplayLists....


mp3butcher wrote:
> 
> 
> robertosfield wrote:
> > Hi Julian,
> > 
> > I have just reviewed the code and understand the logic of the change,
> > just looking at the local code it's what would seem the appropriate
> > implementation.  However, the original code is probably more robust.
> > If you have two adjacent PrimitiveSet within the same osg::Geometry
> > but didn't all use EBO then you'd end up with an EBO being still bound
> > when it shouldn’t be.  I realise this case won't be common and will
> > generally be undesirable it's a condition that won't be able to
> > enforce without adding more checks elsewhere.
> > 
> > 
> 
> I don't understand the use case you described.
> When you're writing about primset that doesn't use EBO, do you refer to 
> DrawArrays? 
> Because if you refer to DrawElements that doesn't use EBO (the else path in 
> "DrawElementsXX::draw's if(ebo)" ) the current code would crash before 
> reaching it ( on state.bindElementBufferObject(ebo) );
> And if you're refering as I expect to DrawArrays the fact that there's EBO 
> currently bound there isn't any incidence as the drawArrays call will simply 
> ignore it...?!
> 
> So to stay simple how can to else path in "DrawElementsXX::draw's if(ebo)" 
> could ever be reached without crashing on state.bindElementBufferObject(ebo) 
> if the precedently drawn primset have ebo attached? 
> 
> 
> robertosfield wrote:
> > 
> > 
> > Since one will normally use VBO and EBO at the same time the code path
> > that the CPU will take will essentially do all the same operations in
> > both the original code and your proposed change, so for normal usage
> > it won't be any more efficient.  Given there is a possibility of a bug
> > appearing due to the lack of unbinding between PrimitiveSet I don't
> > feel it would be appropriate to adopt it.
> > 
> 


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http://forum.openscenegraph.org/viewtopic.php?p=67708#67708





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