Hi Alan,
I have never thought about trying to render an entire OSG scene to
FBO, and don't actually have any clear idea what bits you'd need to
tweak to achieve it. Perhaps one possibility would be assign the FBO
outwith the SceneView::draw(), or have a custom SceneView override the
draw to implement you own FBO set up. You could probably reuse the
osg::FrameBufferObject for this task.
The other alterntive would be to use a pbuffer, again done outside the
SceneView::draw(), however, it might be just as much extra complexity
as using a FBO, and woud force a copy of data.
Robert.
On 6/21/06, Alan Ott <[EMAIL PROTECTED]> wrote:
Hello,
I have a non-OSG OpenGL application in which I need to draw an OSG
Scene. My OSG scene is required to be drawn in up to 3 places on the
screen. What I would like to do is render my OSG scene to an FBO, and
have the non-OSG application then draw a polygon with my FBO texture on it.
I have a small test app where I render to an FBO, and draw that texture
onto an OSG polygon which works great (similar to the osgfbo example).
My problem now is that to do this, I use a SceneView object which draws
directly to the main framebuffer. I would like to have none of my code
touch the main framebuffer or global state at all, but render only to an
FBO.
The goal for now is to have a simple GLUT application, which calls my
OSG code to create the scene (to FBO only), then draws a textured quad
with my FBO texture on it using raw GL calls (similar to the way it
would work in the non-OSG app).
My questions are:
1. Is there some way to not use a SceneView, and is this desirable?
2. Is there some way to make the SceneView not touch the main frame
buffer or global state?
3. Is an FBO even the right choice for this? Would a pbuffer be better?
4. Am I going to need a whole separate OpenGL context (as with a
pbuffer) to do this right?
Thanks for any help.
Alan.
PS: I did something similar before and there are a couple of posts to
the mailing list about it sometime last September or October. Like this
problem, I had to draw to a non-OSG application, but unlike this
problem, I could draw directly to the main framebuffer. In this case, I
can't because my image needs to be drawn in up to 3 places in the main
application, so I can't use the main framebuffer directly.
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