Hi Mathias,
I don't what the problem is, but the OSG uses lazy state updating that
is managed via osg::State, so there is a chance that state set
elsewhere w.r.t vertex set up is effecting your drawable, or the other
way around.
Robert.
On Mon, Jan 25, 2010 at 10:09 AM, Mattias Thell <mattias.th...@gmail.com> wrote:
> Hi,
>
> In the implementation of a Drawable subclass, I am trying to use regular GL
> functions to render primitives through vertex buffer objects. Like so:
>
> Init:
>
> Code:
>
> Drawable::Extensions* ext = getExtensions(state.getContextID(), true);
>
> GLfloat v[] = {
> 0.0f, 0.0f, 0.0f, 1.0f,
> 2.0f, 0.0f, 0.0f, 1.0f,
> 2.0f, 2.0f, 0.0f, 1.0f
> };
>
> ext->glGenBuffers(1, & b);
> ext->glBindBuffer(GL_ARRAY_BUFFER_ARB, b);
> ext->glBufferData(GL_ARRAY_BUFFER_ARB, sizeof(v), v, GL_STATIC_DRAW);
>
>
>
>
> drawImplementation(..)
>
> Code:
>
> osg::State& state = *renderInfo.getState();
> Drawable::Extensions* ext = getExtensions(state.getContextID(), true);
>
> ext->glBindBuffer(GL_ARRAY_BUFFER_ARB, b);
> glEnableClientState(GL_VERTEX_ARRAY);
>
> glVertexPointer(4, GL_FLOAT, 0, 0);
>
> glDrawArrays(GL_POINTS, 0, 3);
>
> glDisableClientState(GL_VERTEX_ARRAY);
> ext->glBindBuffer(GL_ARRAY_BUFFER_ARB, 0);
>
>
>
>
> But, nothing shows up on the screen. There are no GL errors reported.
> Changing the code to use regular vertex arrays (without binding the vbo and
> changing the glVertexPointer call to take an array), things shows up fine.
> Ofcourse, this is not what I want.
>
> I even created a stand-alone skeleton GL application with this kind of
> implementation, and as expected, it works fine.
>
> So, it must be the case that OSG does some trickery of its own. The question
> is, what could that be? :?
>
> Thank you!
>
> Cheers,
> Mattias
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=23125#23125
>
>
>
>
>
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>
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