Hi,
i'm finding a lot of difficult to solve this issue: pass uniform and attribute
parameters from osg application to shader.
In particular, referred to attribute (or in) parameter in vertex program :
Code:
#version 150
attribute vec3 Vertex;
attribute vec2 Uv;
uniform mat4 osg_ProjectionMatrix;
uniform mat4 ViewMatrix;
uniform mat4 osg_ViewMatrixInverse;
uniform vec3 ModelScale;
How can i pass these data from my osg application?
Currently, in my osg applycation i use :
Code:
mProgram->addBindAttribLocation("Vertex",0);
mProgram->addBindAttribLocation("Uv",8);
Is it correct?
I looked at an example on "OpenSceneGraph 3 cookbook" chapter 6, "Using the
bump tecnique" where to pass these attributes :
Code:
attribute vec3 tangent;
attribute vec3 binormal;
The authors (Rui Wang, Xuelei Qian) use a ComputeTangentVisitor nodevisitor
class to compute tangent and binormal for each vertex:
Code:
class ComputeTangentVisitor : public osg::NodeVisitor
{
public:
void apply( osg::Node& node ) { traverse(node); }
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 ) generateTangentArray( geom );
//setGeometryVertexArray(geom);
}
traverse( node );
}
void generateTangentArray( osg::Geometry* geom )
{
osg::ref_ptr<osgUtil::TangentSpaceGenerator> tsg = new
osgUtil::TangentSpaceGenerator;
tsg->generate( geom );
geom->setVertexAttribArray( 6, tsg->getTangentArray() );
geom->setVertexAttribBinding( 6,
osg::Geometry::BIND_PER_VERTEX );
geom->setVertexAttribArray( 7, tsg->getBinormalArray()
);
geom->setVertexAttribBinding( 7,
osg::Geometry::BIND_PER_VERTEX );
}
};
and bind them with the following code :
Code:
ComputeTangentVisitor ctv;
ctv.setTraversalMode( osg::NodeVisitor::TRAVERSE_ALL_CHILDREN );
mModel->accept( ctv );
mProgram->addBindAttribLocation("tangent",6);
mProgram->addBindAttribLocation("binormal",7);
But, in my case vertex are already exist. So i suppose to use only :
mProgram->addBindAttribLocation("Vertex",0);
And what about the Uv parameter? The texture i have to pass to fragment, is a
RTT Camera image, on which i would like to apply some effects.
How can i pass these texture coordinates to shader?
About the uniform parameters, is there a way to pass the ViewMatrix?
I used myCamera->getViewMatrix() in my osgapplication, and i set uniform to
this value inside a callback:
Code:
osg::ref_ptr<osg::Uniform> viewUniformParam = new osg::Uniform("ViewMatrix",
osg::Matrixf());
viewUniformParam->setUpdateCallback( new
ViewMatrixCallback(mApplicationCamera.get()) );
with :
Code:
class ViewMatrixCallback : public osg::Uniform::Callback
{
public:
ViewMatrixCallback(osg::Camera* appcamera):
osg::Uniform::Callback()
{
mApplicationCamera=appcamera;
};
virtual void operator()( osg::Uniform* uniform,
osg::NodeVisitor* nv )
{
osg::Matrix
vmFromCamera=mApplicationCamera->getViewMatrix();
uniform->set( vmFromCamera );
}
protected:
osg::ref_ptr<osg::Camera> mApplicationCamera;
};
But i get no results.
Could you give me some suggestions?
Thank you!
Cheers,
Andrea
------------------
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http://forum.openscenegraph.org/viewtopic.php?p=52925#52925
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