If you are drawing using programmability into a pbuffer context you
must enable and disable state for that context as you would any other.
SInce the programs draw into the pbuffer context you will obviously
need the proper state set in that context. The context you are
texturing to has nothing to do with this and will just have to have the
proper state for texturing.
In the end a pbuffer is just a drawable and it's context is just a
context. The only place that there is any difference is the texturing
where you have to use the specific texturing call that know how to
texture from a pbuffer's drawable.
Of the two operations that are occurring it would be helpful to know
which fails. To do this draw to the pbuffer with your program, use
something like read pixels to copy this to a buffer/image than you can
verify (obviously ensure this copy code works with a standard window).
If this work than test the texturing of any content with from the
pbuffer. Once this works ensure combine the two and ensure you are not
mixing your state settings and you absolutely know which context is
current for any given OpenGL call.
Don't know, maybe this will help.
BTW, the simple answer to your question, is yes but it is no different
that any other context using programs (thus there is no different
documentation, the same parts of the OpenGL spec apply). The same
proper state must be set, which may include the shader (as these are
OpenGL calls which go only to the current context).
On Nov 16, 2004, at 6:21 AM, Gordon Erlebacher wrote:
I have some more information that might solve my problem (with your
help if I am lucky):
I am using Glut.
I have created a pbuffer.
I can write to the pbuffer and from the pbuffer to the screen using
the fixed pipeline.
I can also write to the screen using a pixel shader (ARB)
However, I cannot write to the pbuffer using the shader. For example,
the following code, that
writes to the pbuffer, clears the pbuffer screen and fills it with red
(which eventually appears on the screen).
However, the shader, which changes the color from red to yellow, has
no effect. Yet, when I simply change
the current context from pbuffer to screen, the shader works as it
should and the background red color is
overwritten.
This suggests to me that somehow, the pbuffer context must be active
when certain aspects of the shader
are defined, although I have not seen this documented anywhere. Any
thoughts on the matter? Thanks.
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