[osg-users] attribute variable transfers error

[allan xia]

I am sorry I did not describe the solution clearly.
Now I need to do some extra operations in the models,so I must use shaders
.And different models have little different operations,but mostly same
operations, So I use the same shaders and send a flag variable to the
shaders to judge which model the vertexs belong to. then I could solve the
different operations. and now I use the nodevisitor to judge which model
the vertex belongs to ,but I occur error.
Actually the problem I need to solve is:
how the judge which model the vertex belongs to in the vertex shaders and
fragment shaders?

thanks

Date: Wed, 22 Apr 2015 10:58:35 +0100
From: Robert Osfield <robert.osfield at gmail.com>
To: OpenSceneGraph Users <osg-users at lists.openscenegraph.org>
Subject: Re: [osg-users] attribute variable transfers error
Message-ID:
        <CAFN7Y+XeofDyFr9H9Z9j+sOSnQAi+SzuyaUuOvkDvGiSQdyBdQ at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Hi Allan,

Could you take a step back and tells us what problem you are trying to
solve as you've dived in with a rather perplexing implementation for a
problem that may well have a very straight forward solution.

Robert.

On 22 April 2015 at 10:34, allan xia <softpeo at gmail.com> wrote:
>  I need to distinguish the vertexs in different models in vertex shaders
and
> fragment shaders  .so I use a nodevisitor to transfer a attribute variable
> to the vertex shaders.as follows:
> I transfer different value to the vertex  shader if the type is defined
> different.
>
> class AnalysisNodeVisitor :public osg::NodeVisitor{
> public:
> AnalysisNodeVisitor(INPUTTYPE
> type):osg::NodeVisitor(osg::NodeVisitor::TRAVERSE_ALL_CHILDREN){
> m_InputType=type;
> }
> virtual void apply(osg::Geode &node)
> {
> for ( unsigned int i=0; i<node.getNumDrawables(); ++i )
> {
> osg::Geometry* geom = dynamic_cast<osg::Geometry*>(node.getDrawable(i) );
> if ( geom ){
> osg::FloatArray *fa=new osg::FloatArray;
> switch(m_InputType){
> case INPUTTEXTURE:
> {
> fa->push_back(0.1);
> break;
> }
> case INPUTMATERIAL:
> {
> fa->push_back(0.2);
> break;
> }
> default :
> {
> fa->push_back(0.9);
> }
> }
> geom->setVertexAttribArray(6,fa);
> geom->setVertexAttribBinding(6,osg::Geometry::BIND_OVERALL);
> }
> }
> traverse( node );
> }
> virtual void apply(osg::Node &node){
> traverse(node);
> }
> public:
> INPUTTYPE m_InputType;
> };
>
> and bind the attribute to the shader:
> program->addBindAttribLocation("modelType",6);
>
> but when I use the AnalysisNodeVisitor,I occur a error.
>
> AnalysisNodeVisitor anvA(INPUTTEXTURE);
> nodeA.accept(anvA);
> AnalysisNodeVisitor anvB(INPUTMATERIAL);
> nodeB.accept(anvB);
>
> and in the vertex shader  modelType variable of vertexs in nodeA should be
> 0.1 and modeType variable of vertexs in NodeB should be 0.2 ,but actually
> modeType variable of all vertex is 0.2 .It seems nodeB.accept(anvB)
override
> the modeType variable of nodeA. what is wrong with it?Am I misunderstand
it
> ?
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