[osg-users] [osgPango] Alpha when rendering letters

2011-05-27 Thread Sergey Kurdakov 
Hi,

I use osgPango to render text ( latest version from svn ).

from what I got from code,  first glyphs are rendered to layers, then
default shader puts
everything into frontbuffer  ( default is frag1 shader - which I use ).

However - due to use of alpha in shader the text looks somewhat not very
crisp
( some parts of letters appear as if they have some alpha ( I render  above
alpha texture but with osgPango node
with blend option switched off  - but still shader takes it into account)

from shader generator  baseFragmentHeader(unsigned int num)

there is a statement

return vec4(c.rgb * t.a, t.a);

so - naturally alpha is present in output pixel.

Replacing the string

to

return vec4(c.rgb, t.a);

does not change  much.

but

return vec4(c.rgb , 1.0 );

renders everything outside letters  with black ( so instead of text - filled
rectangles ).

now, maybe I miss something simple
but how to filter
alpha so that
I have less fuzzy letters and also do not produce non needed artifacts.


Regards
Sergey
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Re: [osg-users] [osgPango] Alpha when rendering letters

2011-05-27 Thread Jeremy Moles 
Can you send me an example showing this? I can probably fix the problem
right up when I see the code.

However, unless you've got some FFP blending setup elsewhere in your
scene, I'm having a hard time imagining what could be wrong...

On Fri, 2011-05-27 at 23:46 +0400, Sergey Kurdakov wrote:
 Hi,
 
 I use osgPango to render text ( latest version from svn ).
 
 
 from what I got from code,  first glyphs are rendered to layers, then
 default shader puts 
 everything into frontbuffer  ( default is frag1 shader - which I
 use ).
 
 
 However - due to use of alpha in shader the text looks somewhat not
 very crisp
 ( some parts of letters appear as if they have some alpha ( I render
  above alpha texture but with osgPango node 
 with blend option switched off  - but still shader takes it into
 account)
 
 
 from shader generator  baseFragmentHeader(unsigned int num)
 
 
 there is a statement
 
 
 return vec4(c.rgb * t.a, t.a);
 
 
 so - naturally alpha is present in output pixel.
 
 
 Replacing the string
 
 
 to
 
 
 return vec4(c.rgb, t.a);
 
 
 does not change  much.
 
 
 but
 
 
 return vec4(c.rgb , 1.0 );
 
 
 renders everything outside letters  with black ( so instead of text -
 filled rectangles ).
 
 
 now, maybe I miss something simple
 but how to filter
 alpha so that
 I have less fuzzy letters and also do not produce non needed
 artifacts.
 
 
 
 
 Regards
 Sergey
 
 
 
 
 
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 osg-users@lists.openscenegraph.org
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