openGL MSAA在带有nouveau驱动程序的linux上不起作用

最近我尝试在 Linux下使用MSAA(多重采样抗锯齿).结果令人惊讶：一切都像Nvidia专有驱动程序的魅力一样,但是有了nouveau驱动程序它不起作用.关于这一点的奇怪之处在于glxingo说支持GLX_ARB_multisample并且我能够获得适当的FBConfig,GLX_SAMPLE_BUFFERS设置为1,GLX_SAMPLES设置为4(或8).但是在渲染时,图片没有应用抗锯齿.我的项目和freeglut都存在这个问题,所以我将提供一个基于过剩的小程序来证明这个问题：

/*
 * Test multisampling and polygon smoothing.
 *
 * Brian Paul
 * 4 November 2002
 */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>


static GLfloat Zrot = 0;
static GLboolean Anim = GL_TRUE;
static GLboolean HaveMultisample = GL_TRUE;
static GLboolean DoMultisample = GL_TRUE;


static void
PrintString(const char *s)
{
   while (*s) {
      glutBitmapCharacter(GLUT_BITMAP_8_BY_13,(int) *s);
      s++;
   }
}


static void
Polygon( GLint verts,GLfloat radius,GLfloat z )
{
   int i;
   for (i = 0; i < verts; i++) {
      float a = (i * 2.0 * 3.14159) / verts;
      float x = radius * cos(a);
      float y = radius * sin(a);
      glVertex3f(x,y,z);
   }
}


static void
DrawObject( void )
{
   glLineWidth(3.0);
   glColor3f(1,1,1);
   glBegin(GL_LINE_LOOP);
   Polygon(12,1.2,0);
   glEnd();

   glLineWidth(1.0);
   glColor3f(1,1.1,0);
   glEnd();

   glColor3f(1,0);
   glBegin(GL_POLYGON);
   Polygon(12,0.4,0.3);
   glEnd();

   glColor3f(0,0.6,0.2);
   glEnd();

   glColor3f(0,1);
   glBegin(GL_POLYGON);
   Polygon(12,0.8,0.1);
   glEnd();

   glColor3f(1,1.0,0);
   glEnd();
}


static void
Display( void )
{
   glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

   glColor3f(1,1);
   if (HaveMultisample) {
      glRasterPos2f(-3.1,-1.6);
      if (DoMultisample)
         PrintString("MULTISAMPLE");
      else
         PrintString("MULTISAMPLE (off)");
   }
   glRasterPos2f(-0.8,-1.6);
   PrintString("No antialiasing");
   glRasterPos2f(1.6,-1.6);
   PrintString("GL_POLYGON_SMOOTH");

   /* multisample */
   if (HaveMultisample) {
      glEnable(GL_DEPTH_TEST);
      if (DoMultisample)
         glEnable(GL_MULTISAMPLE_ARB);
      glPushMatrix();
      glTranslatef(-2.5,0);
      glPushMatrix();
      glRotatef(Zrot,1);
      DrawObject();
      glPopMatrix();
      glPopMatrix();
      glDisable(GL_MULTISAMPLE_ARB);
      glDisable(GL_DEPTH_TEST);
   }

   /* non-aa */
   glEnable(GL_DEPTH_TEST);
   glPushMatrix();
   glTranslatef(0,0);
   glPushMatrix();
   glRotatef(Zrot,1);
   DrawObject();
   glPopMatrix();
   glPopMatrix();
   glDisable(GL_DEPTH_TEST);

   /* polygon smooth */
   glEnable(GL_POLYGON_SMOOTH);
   glEnable(GL_LINE_SMOOTH);
   glEnable(GL_BLEND);
   glPushMatrix();
   glTranslatef(2.5,1);
   DrawObject();
   glPopMatrix();
   glPopMatrix();
   glDisable(GL_LINE_SMOOTH);
   glDisable(GL_POLYGON_SMOOTH);
   glDisable(GL_BLEND);

   glutSwapBuffers();
}


static void
Reshape( int width,int height )
{
   GLfloat ar = (float) width / (float) height;
   glViewport( 0,width,height );
   glMatrixMode( GL_PROJECTION );
   glLoadIdentity();
   glOrtho(-2.0*ar,2.0*ar,-2.0,2.0,-1.0,1.0);
   glMatrixMode( GL_MODELVIEW );
   glLoadIdentity();
}


static void
Idle( void )
{
   Zrot = 0.01 * glutGet(GLUT_ELAPSED_TIME);
   glutPostRedisplay();
}


static void
Key( unsigned char key,int x,int y )
{
   const GLfloat step = 1.0;
   (void) x;
   (void) y;
   switch (key) {
      case 'a':
         Anim = !Anim;
         if (Anim)
            glutIdleFunc(Idle);
         else
            glutIdleFunc(NULL);
         break;
      case 'm':
         DoMultisample = !DoMultisample;
         break;
      case 'z':
         Zrot = (int) (Zrot - step);
         break;
      case 'Z':
         Zrot = (int) (Zrot + step);
         break;
      case 27:
         exit(0);
         break;
   }
   glutPostRedisplay();
}


static void
Init( void )
{
   /* GLUT imposes the four samples/pixel requirement */
   int s;
   glGetIntegerv(GL_SAMPLES_ARB,&s);
   if (!glutExtensionSupported("GL_ARB_multisample") || s < 1) {
      printf("Warning: multisample antialiasing not supported.n");
      HaveMultisample = GL_FALSE;
   }
   printf("GL_RENDERER = %sn",(char *) glGetString(GL_RENDERER));
   printf("GL_SAMPLES_ARB = %dn",s);

   glBlendFunc(GL_SRC_ALPHA,GL_ONE);
   glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
   glBlendFunc(GL_SRC_ALPHA_SATURATE,GL_ONE);

   glGetIntegerv(GL_MULTISAMPLE_ARB,&s);
   printf("GL_MULTISAMPLE_ARB = %dn",s);
}


int
main( int argc,char *argv[] )
{
   glutInit( &argc,argv );
   glutInitWindowPosition( 0,0 );
   glutInitWindowSize( 600,300 );
   glutInitDisplayMode( GLUT_RGB | GLUT_ALPHA | GLUT_DOUBLE |
                        GLUT_DEPTH | GLUT_MULTISAMPLE );
   glutCreateWindow(argv[0]);
   glutReshapeFunc( Reshape );
   glutKeyboardFunc( Key );
   glutDisplayFunc( Display );
   if (Anim)
      glutIdleFunc( Idle );
   Init();
   glutMainLoop();
   return 0;
}

这是glxinfo输出(不包括视觉信息)：

name of display: :0.0
display: :0  screen: 0
direct rendering: Yes
server glx vendor string: SGI
server glx version string: 1.4
server glx extensions:
    GLX_ARB_multisample,GLX_EXT_import_context,GLX_EXT_texture_from_pixmap,GLX_EXT_visual_info,GLX_EXT_visual_rating,GLX_MESA_copy_sub_buffer,GLX_OML_swap_method,GLX_SGI_swap_control,GLX_SGIS_multisample,GLX_SGIX_fbconfig,GLX_SGIX_pbuffer,GLX_SGIX_visual_select_group,GLX_INTEL_swap_event
client glx vendor string: Mesa Project and SGI
client glx version string: 1.4
client glx extensions:
    GLX_ARB_create_context,GLX_ARB_create_context_profile,GLX_ARB_get_proc_address,GLX_ARB_multisample,GLX_EXT_framebuffer_sRGB,GLX_EXT_create_context_es2_profile,GLX_MESA_multithread_makecurrent,GLX_MESA_swap_control,GLX_OML_sync_control,GLX_SGI_make_current_read,GLX_SGI_video_sync,GLX_INTEL_swap_event
GLX version: 1.4
GLX extensions:
    GLX_ARB_get_proc_address,GLX_EXT_texture_from_pixmap
OpenGL vendor string: nouveau
OpenGL renderer string: Gallium 0.4 on NVC1
OpenGL version string: 2.1 Mesa 8.0.4
OpenGL shading language version string: 1.30
OpenGL extensions:
    GL_ARB_multisample,GL_EXT_abgr,GL_EXT_bgra,GL_EXT_blend_color,GL_EXT_blend_minmax,GL_EXT_blend_subtract,GL_EXT_copy_texture,GL_EXT_polygon_offset,GL_EXT_subtexture,GL_EXT_texture_object,GL_EXT_vertex_array,GL_EXT_compiled_vertex_array,GL_EXT_texture,GL_EXT_texture3D,GL_IBM_rasterpos_clip,GL_ARB_point_parameters,GL_EXT_draw_range_elements,GL_EXT_packed_pixels,GL_EXT_point_parameters,GL_EXT_rescale_normal,GL_EXT_separate_specular_color,GL_EXT_texture_edge_clamp,GL_SGIS_generate_mipmap,GL_SGIS_texture_border_clamp,GL_SGIS_texture_edge_clamp,GL_SGIS_texture_lod,GL_ARB_framebuffer_sRGB,GL_ARB_multitexture,GL_EXT_framebuffer_sRGB,GL_IBM_multimode_draw_arrays,GL_IBM_texture_mirrored_repeat,GL_ARB_texture_cube_map,GL_ARB_texture_env_add,GL_ARB_transpose_matrix,GL_EXT_blend_func_separate,GL_EXT_fog_coord,GL_EXT_multi_draw_arrays,GL_EXT_secondary_color,GL_EXT_texture_env_add,GL_EXT_texture_filter_anisotropic,GL_EXT_texture_lod_bias,GL_INGR_blend_func_separate,GL_NV_blend_square,GL_NV_light_max_exponent,GL_NV_texgen_reflection,GL_NV_texture_env_combine4,GL_SUN_multi_draw_arrays,GL_ARB_texture_border_clamp,GL_ARB_texture_compression,GL_EXT_framebuffer_object,GL_EXT_texture_env_combine,GL_EXT_texture_env_dot3,GL_MESA_window_pos,GL_NV_packed_depth_stencil,GL_NV_texture_rectangle,GL_ARB_depth_texture,GL_ARB_occlusion_query,GL_ARB_shadow,GL_ARB_texture_env_combine,GL_ARB_texture_env_crossbar,GL_ARB_texture_env_dot3,GL_ARB_texture_mirrored_repeat,GL_ARB_window_pos,GL_EXT_stencil_two_side,GL_EXT_texture_cube_map,GL_NV_depth_clamp,GL_NV_fog_distance,GL_APPLE_packed_pixels,GL_APPLE_vertex_array_object,GL_ARB_draw_buffers,GL_ARB_fragment_program,GL_ARB_fragment_shader,GL_ARB_shader_objects,GL_ARB_vertex_program,GL_ARB_vertex_shader,GL_ATI_draw_buffers,GL_ATI_texture_env_combine3,GL_EXT_shadow_funcs,GL_EXT_stencil_wrap,GL_MESA_pack_invert,GL_NV_primitive_restart,GL_ARB_depth_clamp,GL_ARB_fragment_program_shadow,GL_ARB_half_float_pixel,GL_ARB_occlusion_query2,GL_ARB_point_sprite,GL_ARB_shading_language_100,GL_ARB_sync,GL_ARB_texture_non_power_of_two,GL_ARB_vertex_buffer_object,GL_ATI_blend_equation_separate,GL_EXT_blend_equation_separate,GL_OES_read_format,GL_ARB_color_buffer_float,GL_ARB_pixel_buffer_object,GL_ARB_texture_compression_rgtc,GL_ARB_texture_rectangle,GL_ATI_texture_compression_3dc,GL_EXT_packed_float,GL_EXT_pixel_buffer_object,GL_EXT_texture_compression_rgtc,GL_EXT_texture_mirror_clamp,GL_EXT_texture_rectangle,GL_EXT_texture_sRGB,GL_EXT_texture_shared_exponent,GL_ARB_framebuffer_object,GL_EXT_framebuffer_blit,GL_EXT_framebuffer_multisample,GL_EXT_packed_depth_stencil,GL_ARB_vertex_array_object,GL_ATI_separate_stencil,GL_ATI_texture_mirror_once,GL_EXT_draw_buffers2,GL_EXT_draw_instanced,GL_EXT_gpu_program_parameters,GL_EXT_texture_array,GL_EXT_texture_compression_latc,GL_EXT_texture_integer,GL_EXT_texture_sRGB_decode,GL_EXT_timer_query,GL_OES_EGL_image,GL_MESA_texture_array,GL_ARB_copy_buffer,GL_ARB_depth_buffer_float,GL_ARB_draw_instanced,GL_ARB_half_float_vertex,GL_ARB_instanced_arrays,GL_ARB_map_buffer_range,GL_ARB_texture_rg,GL_ARB_texture_swizzle,GL_ARB_vertex_array_bgra,GL_EXT_separate_shader_objects,GL_EXT_texture_swizzle,GL_EXT_vertex_array_bgra,GL_NV_conditional_render,GL_AMD_conservative_depth,GL_AMD_draw_buffers_blend,GL_ARB_ES2_compatibility,GL_ARB_draw_buffers_blend,GL_ARB_draw_elements_base_vertex,GL_ARB_explicit_attrib_location,GL_ARB_fragment_coord_conventions,GL_ARB_provoking_vertex,GL_ARB_sampler_objects,GL_ARB_seamless_cube_map,GL_ARB_shader_texture_lod,GL_EXT_provoking_vertex,GL_EXT_texture_snorm,GL_MESA_texture_signed_rgba,GL_NV_texture_barrier,GL_ARB_robustness,GL_ARB_transform_feedback2,GL_ARB_conservative_depth,GL_ARB_texture_storage,GL_EXT_transform_feedback

glewIsSupported表示扩展名可用,glGetIntegerv表示获取FBConfig时指定的样本数为4.
我不知道发生了什么.

编辑：这是glXQueryExtensionsString的输出：
GLX_ARB_get_proc_address GLX_ARB_multisample GLX_EXT_import_context GLX_EXT_visual_info GLX_EXT_visual_rating GLX_MESA_copy_sub_buffer GLX_MESA_multithread_makecurrent GLX_MESA_swap_control GLX_OML_swap_method GLX_OML_sync_control GLX_SGI_make_current_read GLX_SGI_swap_control GLX_SGI_video_sync GLX_SGIS_multisample GLX_SGIX_fbconfig GLX_SGIX_pbuffer GLX_SGIX_visual_select_group GLX_EXT_texture_from_pixmap