Hello Michael,
Michael Babcock wrote:
> I need to save the alpha channel to images rendered using OpenSG (1.8
> recent cvs). I'm using a FileGrabForeground and it works fine with a
> normal Viewport.
>
> However I've found that it doesn't work with a ShadowViewport because
> the alpha channel is overwritten with 1. ShadowViewport::setAlpha(false)
> doesn't work.
>
> Looking at the code, the simplest solution is to use
> glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_FALSE) around the
> drawCombineMap() and createShadowFactorMap() functions. However this
> doesn't work if USE_FBO_FOR_COLOR_AND_FACTOR_MAP is defined, and for me
> using FBOs is a win for performance.
>
> So instead I changed the color map texture from GL_RGB to GL_RGBA and
> modified the shadow_combine shader to pass through the alpha instead of
> overwriting it.
>
> I tested with the 5 different tree renderers with and without
> USE_FBO_FOR_COLOR_AND_FACTOR_MAP and it works. I've attached a patch in
> case others run across this issue. Apply in
> Source/Experimental/ShadowViewport.
thank you for sending the patch. I'm somewhat tempted to just apply it
and make this the default, but since it may increase graphics memory
consumption [1] and so far you are the first to need the alpha passed
through, I'm a little uncertain.
Dirk or anybody else here have an opinion on this? Thanks.
Cheers,
Carsten
[1] not sure if it really needs more memory on the graphics card since
i'd almost expect the card to use padding to make sure the RGB triples
are 4 byte aligned.
------------------------------------------------------------------------------
Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
trial. Simplify your report design, integration and deployment - and focus on
what you do best, core application coding. Discover what's new with
Crystal Reports now. http://p.sf.net/sfu/bobj-july
_______________________________________________
Opensg-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/opensg-users
