Hi Robert,
Just some idea, there is also ARB_draw_buffers_blend [1] which lets you
define different blending functions for the render targets. Maybe you
should consider this when designing the draw buffers2 extension
implementation, as it builds upon the buffers2 ext.
[1] https://www.opengl.org/registry/specs/ARB/draw_buffers_blend.txt
Hi Rui,
Sorry for the slow review. Just done a review and feel that how best
to implement this feature is something we need to discuss further.
The issue with the proposed implementation is that state will leak
from the osg::BlendFunc that you set the DrawBufferState on and will
affect any MRT usage out with the subgraph that you apply it to.
Normally with OSG state the default constructed version of a
StateAttribute is applied once all the version of that state have been
popped off the osg::State stack for that attribute. This won't be
possible with these modifications of osg::BlendFunc, and the design
won't really expand easily to handle this case.
My own inclination is that this feature is more closely aligned with
the set up of a MRT osg::Camera and it's subgraph, the MRT Camera
knows exactly how many buffers it managing, and at setup the user
propbably knows whether blending is required, so perhaps the
osg::Camera::Attachment should be extended to handle this case.
Another alternative would be to have a separate StateAttribute for
this new control rather than place it with osg::BlendFunc. This would
still have the issue of how do we manage return the state to
appropriate defaults.
Thoughts?
Robert.
On 9 August 2014 17:51, Wang Rui <[email protected]
<mailto:[email protected]>> wrote:
Hi Robert,
I've just implemented part of the GL_EXT_draw_buffers2 extension
in osg::BlendFunc, which is necessary especially for deferred
shading use. It enables developers to decide which of the multiple
rendering targets (MRT) can be affected by blending function.
Those targets disabling blending are always treated as to save
extra geometry attributes in all 4 channels rather than opacity.
This submissions is originated from the following topic in the
mail list:
http://forum.openscenegraph.org/viewtopic.php?t=13057
And about the extension:
http://www.opengl.org/registry/specs/EXT/draw_buffers2.txt
A new osgblenddrawbuffers example is also submitted to show the
importance and usage of the new functionalities.
Cheers,
Wang Rui
_______________________________________________
osg-submissions mailing list
[email protected]
<mailto:[email protected]>
http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org
_______________________________________________
osg-submissions mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org
_______________________________________________
osg-submissions mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org
