Hi Clement,
clement vidal wrote:
Hi JP
For now I Initialize a texture with the value A, in the shader I put the
value B and I would like to have a the end in the texture the max
blending between the value A and B.
Lets do an example:
I create an texture Tex initialized with color red (1,0,0,1)
I attach my texture to a camera
Camera->attach(osg::Camera::COLOR_BUFFER0, Tex);
I use a shader witch do this treatment: gl_FragData[0] =
vec4(0.0,1.0,0.0,1.0);
And I would like have a yellow (1.0,1.0,0.0,1.0) texture at the end of
the treatment.
For now using an osg::BlendEquation with RGBA_MAX blending, I have if I
define a clearColor to my camera the blending between this clearColor
and the color use in the shader. I think this is normal because the
blendEquation define how the blending is doing between the color
previously in the frame buffer and the added color. But it's not what i
want I would like to have the blending between the color previously in
the texture and the added color.
OK I think I understand better now. To use your texture as input (in
order to kind of make it the background (as you have working with
clearcolour)) you will have to map it onto a quad (screen/camera
projection aligned) [1]. Then you make your camera look at this quad and
the fragment shader would then blend with the texture in the frame
buffer. Reading from and writing to the same texture can sometimes give
problems, so you might have to make a copy for the output (ping-pong,
see osggameoflife).
I'm also not sure why you want to use blending, do you have some special
algorithm that needs it? If you have an initial texture with input
values, you can just sample it in your shader and modify the value
yourself (based on maths, input uniforms or other textures) and put it
into the final texture.
[1] Attachments to the camera are outputs, textures bound to geometry
are used as inputs for RTT.
cheers
jp
Thanks for your help
Clement
2010/1/7 J.P. Delport <jpdelp...@csir.co.za <mailto:jpdelp...@csir.co.za>>
Hi Clement,
could you explain a bit more what you expect and what you are
getting? Do you want to blend between the different textures (AFAIK
you cannot do this unless you do another pass)? Are you expecting
max, but getting average?
jp
clement vidal wrote:
Hi,
I have a problem with BlendEquations and shaders. That is the
situation:
I attach several textures to my camera using COLOR_BUFFER0,
COLOR_BUFFER1, ...
I use a shader to make the rendering into this textures.
There is some values in this textures and i would like to use a
max blending between the value wich are already in and the
values i affect in the shader.
When I define an osg::BlendEquation with RGBA_MAX blending, i
have the blend result between the value in the frame buffer
(background color or ClearColor ) and the value in the shader.
What I do wrong? Somebody have a idea?
Thanks for helping
------------------------------------------------------------------------
_______________________________________________
osg-users mailing list
osg-users@lists.openscenegraph.org
<mailto:osg-users@lists.openscenegraph.org>
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
--
This message is subject to the CSIR's copyright terms and
conditions, e-mail legal notice, and implemented Open Document
Format (ODF) standard. The full disclaimer details can be found at
http://www.csir.co.za/disclaimer.html.
This message has been scanned for viruses and dangerous content by
MailScanner, and is believed to be clean. MailScanner thanks
Transtec Computers for their support.
_______________________________________________
osg-users mailing list
osg-users@lists.openscenegraph.org
<mailto:osg-users@lists.openscenegraph.org>
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
------------------------------------------------------------------------
_______________________________________________
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
--
This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard.
The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html.
This message has been scanned for viruses and dangerous content by MailScanner,
and is believed to be clean. MailScanner thanks Transtec Computers for their support.
_______________________________________________
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
