On Tue, 2012-09-04 at 11:05 -0600, Paul Martz wrote:
> Doesn't a Drawable's state get applied prior to the call to
> Drawable::drawImplementation()? If so, you could just put the _program in
> your
> Drawable's StateSet?
I'm working on a nodekit for NV_path_rendering, which takes an "as of
yet unseen" approach to rendering; new go OpenGL, at any rate. :)
They call it the "Stencil then Cover" approach, and like most 2D vector
drawing libraries, there is a notion of both STROKING _and_ FILLING. In
order to support arbitrary shading on both the affected stroke fragments
and affected fill fragments, I need to be able to potentially set two
different shaders during a single drawable drawImplementation.
Now, having said that--which I potentially should have mentioned in the
first email--does that change any advice you might have? :)
(Thanks for the response, btw... good info.)
> It's easy to verify that things are happening in the right order using a
> debugger with breakpoints set at your drawImplementation() and also at
> Program::apply().
>
> If it doesn't happen as I describe above, then I believe what you're doing
> below
> is the most robust, as that code would work with all other rendering in the
> scene graph, both shader and non-shader rendering.
>
> Honestly it's been too long since I played at this level. But I seem to
> recall
> that the difference between:
> _program->apply( state );
> and
> state->apply( _program.get() );
> is that the latter tracks the currently bound program, doesn't bother to
> apply
> it if it's already in use, and would probably allow you to remove the call to
> setLastAppliedProgramObject(0).
> -Paul
>
>
> On 9/4/2012 9:58 AM, Jeremy Moles wrote:
> > I am creating a custom Drawable that needs to push a Fragment Shader
> > into the current rendering state and then, after a single extension
> > call, subsequently remove this shader from the state.
> >
> > I have some code I noodled through to make this work, but I feel like
> > there is probably a better way. It goes something like this:
> >
> > ----------------------------------------
> >
> > drawImplementaion(RenderInfo& ri) {
> > State* state = ri.getState();
> > unsigned int contextID = state->getContextID();
> >
> > _program.apply(state);
> >
> > myExtensions->doMycall();
> >
> > GL2Extensions::Get(contextID, true)->glUseProgram(0);
> >
> > state->setLastAppliedProgramObject(0);
> > }
> >
> > ----------------------------------------
> >
> > Like I said above, this "works", but I feel like there is probably a
> > cleaner way to achieve what I want. Note that _program is a ref_ptr to a
> > properly create osg::Program object, since I certainly do NOT want to
> > recreate all the goodness it provides. :)
> >
> > Any API advice?
> >
> > _______________________________________________
> > osg-users mailing list
> > [email protected]
> > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
> >
> >
> _______________________________________________
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