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?
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?
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