[vtk-developers] backtrace of segfault in Charts-TestMultipleScalarsToColors on bubbles OSMesa build

[Kevin H. Hobbs]

On 10/27/2010 02:04 PM, Marcus D. Hanwell wrote:
> 
> Thanks Kevin. I don't know of anywhere else where this is failing, but
> thinking about it I don't think we should be calling
> ExtensionSupported until we have an OpenGL context. If you look in the
> TestGLSL.cxx test (in the same directory) I am very careful to test
> for OpenGL features after we get a valid context.
> 

Just for grins I added :

renwin->SetSize(800, 640);
renwin->Render(); // This line
vtkOpenGLRenderWindow* openGLRenWin =
  vtkOpenGLRenderWindow::SafeDownCast(renwin);

and the test passed.

I made a test program :

#include <stdlib.h>
#include "GL/osmesa.h"
#include "GL/glu.h"

static int Width = 400;
static int Height = 400;

int main( int argc, char * argv[] )
{

  //OSMesaContext ctx = OSMesaCreateContext( OSMESA_RGBA, NULL );
  void *buffer;
  const char *gl_renderer;
  buffer = malloc( Width * Height * 4 * sizeof(GLubyte) );
  //OSMesaMakeCurrent( ctx, buffer, GL_UNSIGNED_BYTE, Width, Height );
  gl_renderer=(const char *)glGetString(GL_VERSION_1_2);
  return 0;
}

compiled with :

gcc \
  -Xlinker "-rpath=/home/kevin/mesa_osmesa/lib" \
  -Lmesa_osmesa/lib/ \
  -lOSMesa -lGLU mesatest.c

it segfaults at :

glGetString () at glapi_x86-64.S:9876

just like the VTK test.

With both the OSMesaCreateContext and OSMesaMakeCurrent lines
uncommented it completes successfully.

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