Hi Raymond,
Are you writing your own custom OpenGL code? If so then it's likely
that you aren't telling the OSG about the state changes you are
making, or you are assuming OpenGL state is in a certain configuration
in your own code, but this state isn't actually current. For instance
if a vertex array is enabled by you don't provide a valid pointer then
you'll like get a crash.
The "fix" you've made effectively discards lazy state updating and
even using a glGet, glGet being the worst offender as it can stall the
graphics pipeline so is only something you'll want to call on start
up, not during rendering.
As for giving you guidance on what you are doing wrong, this is hard
given I don't really know what you are doing. In general you'll need
to make sure the OpenGL state is the one you want before you doing you
own OpenGL code, and any state changes you make you need to tell the
OSG about afterwards so its lazy state updating can work correctly.
The haveApplied methods help with this, as do the vertex pointer
methods provided in osg::State. Review how osg:::Geometry does
things for inspiration.
Robert.
On Fri, May 30, 2008 at 3:59 PM, Raymond de Vries <[EMAIL PROTECTED]> wrote:
> Hi,
>
> I just wanted to let you know that I fixed my crash with a straight forward
> implementation of the function that I mentioned earlier today. This is of
> course by no means a real fix in the osg way but for that I simply don't
> know all the tiny details of the optimizations.
>
> The problem occured when I reloaded my scene with (a changed version, with
> vertex attributes, of) precipitation. What I suspect what happened is that a
> vertex attribute unit was still activated from the previously loaded scene,
> while it should have been disabled after loading the scene again.
>
> Of course it should be fixed elsewhere, but this is how I fixed it, in a
> straightforward way, unconditionally:
> void State::disableVertexAttribPointersAboveAndIncluding( unsigned int index
> )
> {
> if (_glDisableVertexAttribArray)
> {
> // Fix by RdV, to avoid a crash when a non-existing vertex array is still
> bound, 20080530
> #if 0
> while (index< _vertexAttribArrayList.size())
> {
> EnabledArrayPair& eap = _vertexAttribArrayList[index];
> if (eap._enabled || eap._dirty)
> {
> eap._enabled = false;
> eap._dirty = false;
> _glDisableVertexAttribArray( index );
> }
> ++index;
> }
> #else
> int maximumNoOfVertexAttributes;
> glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &maximumNoOfVertexAttributes);
> while (index < maximumNoOfVertexAttributes) {
> _glDisableVertexAttribArray( index );
> index++;
> }
> #endif
> }
> }
>
> and I needed an unconditional enabling of the vertex attribute unit as well:
> void State::setVertexAttribPointer( unsigned int index,
> GLint size, GLenum type, GLboolean
> normalized,
> GLsizei stride, const GLvoid *ptr )
> {
> if (_glVertexAttribPointer)
> {
> if ( index >= _vertexAttribArrayList.size())
> _vertexAttribArrayList.resize(index+1);
> EnabledArrayPair& eap = _vertexAttribArrayList[index];
>
> // Fix by RdV, to avoid a crash when a non-existing vertex array is
> still bound, 20080530
> #if 0
> if (!eap._enabled || eap._dirty)
> {
> eap._enabled = true;
> _glEnableVertexAttribArray( index );
> }
> #else
> _glEnableVertexAttribArray( index );
> #endif
> //if (eap._pointer != ptr || eap._normalized!=normalized ||
> eap._dirty)
> {
> _glVertexAttribPointer( index, size, type, normalized, stride, ptr
> );
> eap._pointer = ptr;
> eap._normalized = normalized;
> }
> eap._dirty = false;
> }
> }
> I did this fix in osg-2.2.0 but the func still exists as-is in svn.
> Hopefully this triggers a fix in the osg way by you.
>
> Cheers
> Raymond
>
>
>
>
> Raymond de Vries wrote:
>>
>> Hi,
>>
>> I am trying to add vertex attributes to my shader program and I am having
>> a crash when I reload the geometry with vertex attributes.
>>
>> Now I am looking into the source and came across the func
>> osg::State::disableVertexAttribPointersAboveAndIncluding(). Looking at the
>> func name I would expect that the vertex attribute units would be disabled,
>> but it doesn't count up. I am really new in this area and would like to
>> learn. Is there someone who can explain this piece?
>>
>> Mike Weiblen, could you take a look maybe, you're a shader expert!
>>
>> A related question: I see that 'some' vertex attribute units are used in
>> examples like the glsl_confetti.osg. Can any unit be used arbitrarily,
>> without 0 which seems to be used for the vertex coordinates?
>>
>> thanks a lot for explaining, best regards
>> Raymond
>>
>>
>> this is in the svn btw
>> _______________________________________________
>> osg-users mailing list
>> [email protected]
>> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>>
>>
>
> _______________________________________________
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