[osg-users] OverlayNode bug

Mathieu MARACHE mathieu.marache at gmail.com
Thu Sep 11 08:00:56 PDT 2008


Hi Robert,

2008/9/10 Robert Osfield <robert.osfield at gmail.com>

> Hi Mathieu,
>
> I don't know the cause/or a solution to the problem, but in the case
> of VIEW_DEPENDENT_WITH_PERSPECTIVE_OVERLAY a GLSL vertex and fragment
> program is used to generate the results, so I'd guess that the shader
> simply doesn't know about the texture blending required.   Have a look
> into the implementation to see if you can get things work.
>

Some updates :
The fragment shader correctly uses the overlay alpha color value to mix
between the original texture and the overlayed texture. So it is not the
shader that is the problem but the RTT camera that produces something wrong.
By tweaking the fragment shader to use the alpha channel on the color
channels it appears that the background of the overlay texture is
transparent and the projected objects are opaque (where they should be
transparent).

Still loooking...

-- 
Mathieu
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