Hi,
clement vidal wrote:
Thanks for your help.
But the solution that you gave me it's not really what I want to do. The
simple example i gave you it's just to explain what kind of result I
need. Actually I'm trying to implement a Dual Depth Peeling based on the
Nvidia Paper and it use this kind of blending. For example in my shader
if I do that:
int i=0;
void main()
{
if(i=0)
{
gl_FragData[0 = vec4(1.0,0.0,0.0,1.0);
i=1;
return;
}
gl_FragData[0] = vec4(0.0,1.0,0.0,1.0);
}
I would like have yellow in my texture for now I have green. Here again
it's just an example, but that's why i would like to use a blend
equation, it's the same problem as the other example I gave you I would
like do a MAX blending between the value previously in the texture and
the new value.
Have you an idea how to do that?
Well your shader only executes once... so AFAIK you can only write once
to the frame buffer in a render pass.
If you want colours to blend with previous ones you first have to create
the previous ones, so you will need multiple passes.
Maybe also see here for inspiration:
http://thread.gmane.org/gmane.comp.graphics.openscenegraph.cvs/6263/
jp
2010/1/7 J.P. Delport <[email protected] <mailto:[email protected]>>
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 <[email protected]
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>>
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
[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>
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
[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
------------------------------------------------------------------------
_______________________________________________
osg-users mailing list
[email protected]
<mailto:[email protected]>
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
[email protected]
<mailto:[email protected]>
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
------------------------------------------------------------------------
_______________________________________________
osg-users mailing list
[email protected]
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
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
