Re: [osg-users] Custom Drawable GLSL
On Tue, 2012-09-04 at 19:21 +0100, Robert Osfield wrote:
Hi Jeremy,
It should be possible to do a
drawImplementation(..)
{
state.apply(stateSetOne);
// do stuff
state.apply(stateSetTwo);
// do more stuff
}
I've settled on:
drawImplementation() {
state.pushStateSet(ss1);
state.apply();
// do stuff
state.popStateSet();
state.apply()
state.pushStateSet(ss1);
state.apply();
// do more stuff
state.popStateSet();
state.apply()
}
Does this seem like an abomination? :) Just calling state.apply() ALMOST
worked, but there was some state leakage (for example, the shader was
applied to all subsequent fragment processing, regardless of it's
location in the graph).
I'm not 100% sure what will happen with the progress of draw traversal
w.r.t how the drawable StateSet if any is applied and then later
assumed to be applied by other state calls. I think it will probably
work out OK though so try it, and if something breaks then considering
adding an extra state.apply(drawwablesStateSet) or a perhaps a state
dirty.
This is something we can workout if required though, try the simplest
thing first then if need be investigate more complicated routes...
Robert.
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[osg-users] Custom Drawable GLSL
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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Re: [osg-users] Custom Drawable GLSL
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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Re: [osg-users] Custom Drawable GLSL
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?
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Re: [osg-users] Custom Drawable GLSL
Hi Jeremy,
It should be possible to do a
drawImplementation(..)
{
state.apply(stateSetOne);
// do stuff
state.apply(stateSetTwo);
// do more stuff
}
I'm not 100% sure what will happen with the progress of draw traversal
w.r.t how the drawable StateSet if any is applied and then later
assumed to be applied by other state calls. I think it will probably
work out OK though so try it, and if something breaks then considering
adding an extra state.apply(drawwablesStateSet) or a perhaps a state
dirty.
This is something we can workout if required though, try the simplest
thing first then if need be investigate more complicated routes...
Robert.
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Re: [osg-users] Custom Drawable GLSL
Hi Jeremy,
In the past I've done similar low-level 2-pass rendering in a Drawable,
by doing as Robert suggests. Apply one stateset, draw, apply another,
draw again (same or different geometry).
A Program is just state, so you need to draw something in between
setting different Programs. Otherwise setting the first Program has no
(visible) effect. I know it sounds obvious but I thought I'd just throw
that out there so there's no ambiguity :-)
Hope this helps,
J-S
On 04/09/2012 1:23 PM, Jeremy Moles wrote:
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?
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http://whitestar02.dyndns-web.com/
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Re: [osg-users] Custom Drawable GLSL
On Tue, 2012-09-04 at 19:15 -0400, Jean-Sébastien Guay wrote:
Hi Jeremy,
In the past I've done similar low-level 2-pass rendering in a Drawable,
by doing as Robert suggests. Apply one stateset, draw, apply another,
draw again (same or different geometry).
A Program is just state, so you need to draw something in between
setting different Programs. Otherwise setting the first Program has no
(visible) effect. I know it sounds obvious but I thought I'd just throw
that out there so there's no ambiguity :-)
Hope this helps,
Hey Paul. :)
It's not simply an issue of setting two similar state attributes in
sequence; the NV_path_rendering API is different enough in that for the
stroke you may want to use a shader and for the fill you may want to
reset the state and use whatever fixed state was available previously,
which is why I've had the issues. HOWEVER, I could just implement
everything as shaders anyways.
What I really seem to need is like a State::save(), State::restore()
kind of thing...
J-S
On 04/09/2012 1:23 PM, Jeremy Moles wrote:
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?
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