src/mesa/main/context.c

/* $Id: context.c,v 1.52 2000/03/31 01:05:51 brianp Exp $ */

/*
 * Mesa 3-D graphics library
 * Version:  3.3
 *
 * Copyright (C) 1999-2000  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


#ifdef PC_HEADER
#include "all.h"
#else
#include "glheader.h"
#include "accum.h"
#include "alphabuf.h"
#include "clip.h"
#include "context.h"
#include "cva.h"
#include "depth.h"
#include "dlist.h"
#include "eval.h"
#include "enums.h"
#include "extensions.h"
#include "fog.h"
#include "get.h"
#include "glapi.h"
#include "glapinoop.h"
#include "glthread.h"
#include "hash.h"
#include "light.h"
#include "macros.h"
#include "matrix.h"
#include "mem.h"
#include "mmath.h"
#include "pb.h"
#include "pipeline.h"
#include "shade.h"
#include "simple_list.h"
#include "stencil.h"
#include "stages.h"
#include "state.h"
#include "translate.h"
#include "teximage.h"
#include "texobj.h"
#include "texstate.h"
#include "texture.h"
#include "types.h"
#include "varray.h"
#include "vb.h"
#include "vbcull.h"
#include "vbrender.h"
#include "vbxform.h"
#include "vertices.h"
#include "xform.h"
#endif



/**********************************************************************/
/*****                  Context and Thread management             *****/
/**********************************************************************/


#if !defined(THREADS)

struct immediate *_mesa_CurrentInput = NULL;

#endif




/**********************************************************************/
/*****                   Profiling functions                      *****/
/**********************************************************************/

#ifdef PROFILE

#include <sys/times.h>
#include <sys/param.h>


/*
 * Return system time in seconds.
 * NOTE:  this implementation may not be very portable!
 */
GLdouble gl_time( void )
{
   static GLdouble prev_time = 0.0;
   static GLdouble time;
   struct tms tm;
   clock_t clk;

   clk = times(&tm);

#ifdef CLK_TCK
   time = (double)clk / (double)CLK_TCK;
#else
   time = (double)clk / (double)HZ;
#endif

   if (time>prev_time) {
      prev_time = time;
      return time;
   }
   else {
      return prev_time;
   }
}

/*
 * Reset the timing/profiling counters
 */
static void init_timings( GLcontext *ctx )
{
   ctx->BeginEndCount = 0;
   ctx->BeginEndTime = 0.0;
   ctx->VertexCount = 0;
   ctx->VertexTime = 0.0;
   ctx->PointCount = 0;
   ctx->PointTime = 0.0;
   ctx->LineCount = 0;
   ctx->LineTime = 0.0;
   ctx->PolygonCount = 0;
   ctx->PolygonTime = 0.0;
   ctx->ClearCount = 0;
   ctx->ClearTime = 0.0;
   ctx->SwapCount = 0;
   ctx->SwapTime = 0.0;
}


/*
 * Print the accumulated timing/profiling data.
 */
static void print_timings( GLcontext *ctx )
{
   GLdouble beginendrate;
   GLdouble vertexrate;
   GLdouble pointrate;
   GLdouble linerate;
   GLdouble polygonrate;
   GLdouble overhead;
   GLdouble clearrate;
   GLdouble swaprate;
   GLdouble avgvertices;

   if (ctx->BeginEndTime>0.0) {
      beginendrate = ctx->BeginEndCount / ctx->BeginEndTime;
   }
   else {
      beginendrate = 0.0;
   }
   if (ctx->VertexTime>0.0) {
      vertexrate = ctx->VertexCount / ctx->VertexTime;
   }
   else {
      vertexrate = 0.0;
   }
   if (ctx->PointTime>0.0) {
      pointrate = ctx->PointCount / ctx->PointTime;
   }
   else {
      pointrate = 0.0;
   }
   if (ctx->LineTime>0.0) {
      linerate = ctx->LineCount / ctx->LineTime;
   }
   else {
      linerate = 0.0;
   }
   if (ctx->PolygonTime>0.0) {
      polygonrate = ctx->PolygonCount / ctx->PolygonTime;
   }
   else {
      polygonrate = 0.0;
   }
   if (ctx->ClearTime>0.0) {
      clearrate = ctx->ClearCount / ctx->ClearTime;
   }
   else {
      clearrate = 0.0;
   }
   if (ctx->SwapTime>0.0) {
      swaprate = ctx->SwapCount / ctx->SwapTime;
   }
   else {
      swaprate = 0.0;
   }

   if (ctx->BeginEndCount>0) {
      avgvertices = (GLdouble) ctx->VertexCount / (GLdouble) ctx->BeginEndCount;
   }
   else {
      avgvertices = 0.0;
   }

   overhead = ctx->BeginEndTime - ctx->VertexTime - ctx->PointTime
              - ctx->LineTime - ctx->PolygonTime;


   printf("                          Count   Time (s)    Rate (/s) \n");
   printf("--------------------------------------------------------\n");
   printf("glBegin/glEnd           %7d  %8.3f   %10.3f\n",
          ctx->BeginEndCount, ctx->BeginEndTime, beginendrate);
   printf("  vertexes transformed  %7d  %8.3f   %10.3f\n",
          ctx->VertexCount, ctx->VertexTime, vertexrate );
   printf("  points rasterized     %7d  %8.3f   %10.3f\n",
          ctx->PointCount, ctx->PointTime, pointrate );
   printf("  lines rasterized      %7d  %8.3f   %10.3f\n",
          ctx->LineCount, ctx->LineTime, linerate );
   printf("  polygons rasterized   %7d  %8.3f   %10.3f\n",
          ctx->PolygonCount, ctx->PolygonTime, polygonrate );
   printf("  overhead                       %8.3f\n", overhead );
   printf("glClear                 %7d  %8.3f   %10.3f\n",
          ctx->ClearCount, ctx->ClearTime, clearrate );
   printf("SwapBuffers             %7d  %8.3f   %10.3f\n",
          ctx->SwapCount, ctx->SwapTime, swaprate );
   printf("\n");

   printf("Average number of vertices per begin/end: %8.3f\n", avgvertices );
}
#endif





/**********************************************************************/
/***** GL Visual allocation/destruction                           *****/
/**********************************************************************/


/*
 * Allocate a new GLvisual object.
 * Input:  rgbFlag - GL_TRUE=RGB(A) mode, GL_FALSE=Color Index mode
 *         alphaFlag - alloc software alpha buffers?
 *         dbFlag - double buffering?
 *         stereoFlag - stereo buffer?
 *         depthBits - requested bits per depth buffer value
 *                     Any value in [0, 32] is acceptable but the actual
 *                     depth type will be GLushort or GLuint as needed.
 *         stencilBits - requested minimum bits per stencil buffer value
 *         accumBits - requested minimum bits per accum buffer component
 *         indexBits - number of bits per pixel if rgbFlag==GL_FALSE
 *         red/green/blue/alphaBits - number of bits per color component
 *                                    in frame buffer for RGB(A) mode.
 *                                    We always use 8 in core Mesa though.
 * Return:  pointer to new GLvisual or NULL if requested parameters can't
 *          be met.
 */
GLvisual *
_mesa_create_visual( GLboolean rgbFlag,
                     GLboolean alphaFlag,
                     GLboolean dbFlag,
                     GLboolean stereoFlag,
                     GLint redBits,
                     GLint greenBits,
                     GLint blueBits,
                     GLint alphaBits,
                     GLint indexBits,
                     GLint depthBits,
                     GLint stencilBits,
                     GLint accumRedBits,
                     GLint accumGreenBits,
                     GLint accumBlueBits,
                     GLint accumAlphaBits,
                     GLint numSamples )
{
   GLvisual *vis;

   /* This is to catch bad values from device drivers not updated for
    * Mesa 3.3.  Some device drivers just passed 1.  That's a REALLY
    * bad value now (a 1-bit depth buffer!?!).
    */
   assert(depthBits == 0 || depthBits > 1);

   if (depthBits < 0 || depthBits > 32) {
      return NULL;
   }
   if (stencilBits < 0 || stencilBits > (GLint) (8 * sizeof(GLstencil))) {
      return NULL;
   }
   if (accumRedBits < 0 || accumRedBits > (GLint) (8 * sizeof(GLaccum))) {
      return NULL;
   }
   if (accumGreenBits < 0 || accumGreenBits > (GLint) (8 * sizeof(GLaccum))) {
      return NULL;
   }
   if (accumBlueBits < 0 || accumBlueBits > (GLint) (8 * sizeof(GLaccum))) {
      return NULL;
   }
   if (accumAlphaBits < 0 || accumAlphaBits > (GLint) (8 * sizeof(GLaccum))) {
      return NULL;
   }

   vis = (GLvisual *) CALLOC( sizeof(GLvisual) );
   if (!vis) {
      return NULL;
   }

   vis->RGBAflag   = rgbFlag;
   vis->DBflag     = dbFlag;
   vis->StereoFlag = stereoFlag;
   vis->RedBits    = redBits;
   vis->GreenBits  = greenBits;
   vis->BlueBits   = blueBits;
   vis->AlphaBits  = alphaFlag ? (8 * sizeof(GLubyte)) : alphaBits;

   vis->IndexBits      = indexBits;
   vis->DepthBits      = depthBits;
   vis->AccumRedBits   = (accumRedBits > 0) ? (8 * sizeof(GLaccum)) : 0;
   vis->AccumGreenBits = (accumGreenBits > 0) ? (8 * sizeof(GLaccum)) : 0;
   vis->AccumBlueBits  = (accumBlueBits > 0) ? (8 * sizeof(GLaccum)) : 0;
   vis->AccumAlphaBits = (accumAlphaBits > 0) ? (8 * sizeof(GLaccum)) : 0;
   vis->StencilBits    = (stencilBits > 0) ? (8 * sizeof(GLstencil)) : 0;

   vis->SoftwareAlpha = alphaFlag;

   if (depthBits == 0) {
      /* Special case.  Even if we don't have a depth buffer we need
       * good values for DepthMax for Z vertex transformation purposes.
       */
      vis->DepthMax = 1;
      vis->DepthMaxF = 1.0F;
   }
   else {
      vis->DepthMax = (1 << depthBits) - 1;
      vis->DepthMaxF = (GLfloat) vis->DepthMax;
   }

   return vis;
}


/* This function should no longer be used. Use _mesa_create_visual() instead */
GLvisual *gl_create_visual( GLboolean rgbFlag,
                            GLboolean alphaFlag,
                            GLboolean dbFlag,
                            GLboolean stereoFlag,
                            GLint depthBits,
                            GLint stencilBits,
                            GLint accumBits,
                            GLint indexBits,
                            GLint redBits,
                            GLint greenBits,
                            GLint blueBits,
                            GLint alphaBits )
{
   return _mesa_create_visual(rgbFlag, alphaFlag, dbFlag, stereoFlag,
                              redBits, greenBits, blueBits, alphaBits,
                              indexBits, depthBits, stencilBits,
                              accumBits, accumBits, accumBits, accumBits, 0);
}


void
_mesa_destroy_visual( GLvisual *vis )
{
   FREE(vis);
}


/* obsolete */
void gl_destroy_visual( GLvisual *vis )
{
   _mesa_destroy_visual(vis);
}



/**********************************************************************/
/***** GL Framebuffer allocation/destruction                      *****/
/**********************************************************************/


/*
 * Create a new framebuffer.  A GLframebuffer is a struct which
 * encapsulates the depth, stencil and accum buffers and related
 * parameters.
 * Input:  visual - a GLvisual pointer
 *         softwareDepth - create/use a software depth buffer?
 *         softwareStencil - create/use a software stencil buffer?
 *         softwareAccum - create/use a software accum buffer?
 *         softwareAlpha - create/use a software alpha buffer?

 * Return:  pointer to new GLframebuffer struct or NULL if error.
 */
GLframebuffer *gl_create_framebuffer( GLvisual *visual,
                                      GLboolean softwareDepth,
                                      GLboolean softwareStencil,
                                      GLboolean softwareAccum,
                                      GLboolean softwareAlpha )
{
   GLframebuffer *buffer;

   buffer = CALLOC_STRUCT(gl_frame_buffer);
   if (!buffer) {
      return NULL;
   }

   /* sanity checks */
   if (softwareDepth ) {
      assert(visual->DepthBits > 0);
   }
   if (softwareStencil) {
      assert(visual->StencilBits > 0);
   }
   if (softwareAccum) {
      assert(visual->RGBAflag);
      assert(visual->AccumRedBits > 0);
      assert(visual->AccumGreenBits > 0);
      assert(visual->AccumBlueBits > 0);
   }
   if (softwareAlpha) {
      assert(visual->RGBAflag);
      assert(visual->AlphaBits > 0);
   }

   buffer->Visual = visual;
   buffer->UseSoftwareDepthBuffer = softwareDepth;
   buffer->UseSoftwareStencilBuffer = softwareStencil;
   buffer->UseSoftwareAccumBuffer = softwareAccum;
   buffer->UseSoftwareAlphaBuffers = softwareAlpha;

   return buffer;
}



/*
 * Free a framebuffer struct and its buffers.
 */
void gl_destroy_framebuffer( GLframebuffer *buffer )
{
   if (buffer) {
      if (buffer->DepthBuffer) {
         FREE( buffer->DepthBuffer );
      }
      if (buffer->Accum) {
         FREE( buffer->Accum );
      }
      if (buffer->Stencil) {
         FREE( buffer->Stencil );
      }
      if (buffer->FrontLeftAlpha) {
         FREE( buffer->FrontLeftAlpha );
      }
      if (buffer->BackLeftAlpha) {
         FREE( buffer->BackLeftAlpha );
      }
      if (buffer->FrontRightAlpha) {
         FREE( buffer->FrontRightAlpha );
      }
      if (buffer->BackRightAlpha) {
         FREE( buffer->BackRightAlpha );
      }
      FREE(buffer);
   }
}



/**********************************************************************/
/*****       Context allocation, initialization, destroying       *****/
/**********************************************************************/


_glthread_DECLARE_STATIC_MUTEX(OneTimeLock);


/*
 * This function just calls all the various one-time-init functions in Mesa.
 */
static void one_time_init( void )
{
   static GLboolean alreadyCalled = GL_FALSE;
   _glthread_LOCK_MUTEX(OneTimeLock);
   if (!alreadyCalled) {
      /* do some implementation tests */
      assert( sizeof(GLbyte) == 1 );
      assert( sizeof(GLshort) >= 2 );
      assert( sizeof(GLint) >= 4 );
      assert( sizeof(GLubyte) == 1 );
      assert( sizeof(GLushort) >= 2 );
      assert( sizeof(GLuint) >= 4 );

      gl_init_clip();
      gl_init_eval();
      _mesa_init_fog();
      _mesa_init_math();
      gl_init_lists();
      gl_init_shade();
      gl_init_texture();
      gl_init_transformation();
      gl_init_translate();
      gl_init_vbrender();
      gl_init_vbxform();
      gl_init_vertices();

      if (getenv("MESA_DEBUG")) {
         _glapi_noop_enable_warnings(GL_TRUE);
      }
      else {
         _glapi_noop_enable_warnings(GL_FALSE);
      }

#if defined(DEBUG) && defined(__DATE__) && defined(__TIME__)
   fprintf(stderr, "Mesa DEBUG build %s %s\n", __DATE__, __TIME__);
#endif

      alreadyCalled = GL_TRUE;
   }
   _glthread_UNLOCK_MUTEX(OneTimeLock);
}



/*
 * Allocate and initialize a shared context state structure.
 */
static struct gl_shared_state *alloc_shared_state( void )
{
   GLuint d;
   struct gl_shared_state *ss;
   GLboolean outOfMemory;

   ss = CALLOC_STRUCT(gl_shared_state);
   if (!ss)
      return NULL;

   ss->DisplayList = _mesa_NewHashTable();

   ss->TexObjects = _mesa_NewHashTable();

   /* Default Texture objects */
   outOfMemory = GL_FALSE;
   for (d = 1 ; d <= 3 ; d++) {
      ss->DefaultD[d] = gl_alloc_texture_object(ss, 0, d);
      if (!ss->DefaultD[d]) {
         outOfMemory = GL_TRUE;
         break;
      }
      ss->DefaultD[d]->RefCount++; /* don't free if not in use */
   }

   if (!ss->DisplayList || !ss->TexObjects || outOfMemory) {
      /* Ran out of memory at some point.  Free everything and return NULL */
      if (ss->DisplayList)
         _mesa_DeleteHashTable(ss->DisplayList);
      if (ss->TexObjects)
         _mesa_DeleteHashTable(ss->TexObjects);
      if (ss->DefaultD[1])
         gl_free_texture_object(ss, ss->DefaultD[1]);
      if (ss->DefaultD[2])
         gl_free_texture_object(ss, ss->DefaultD[2]);
      if (ss->DefaultD[3])
         gl_free_texture_object(ss, ss->DefaultD[3]);
      FREE(ss);
      return NULL;
   }
   else {
      return ss;
   }
}


/*
 * Deallocate a shared state context and all children structures.
 */
static void free_shared_state( GLcontext *ctx, struct gl_shared_state *ss )
{
   /* Free display lists */
   while (1) {
      GLuint list = _mesa_HashFirstEntry(ss->DisplayList);
      if (list) {
         gl_destroy_list(ctx, list);
      }
      else {
         break;
      }
   }
   _mesa_DeleteHashTable(ss->DisplayList);

   /* Free texture objects */
   while (ss->TexObjectList)
   {
      if (ctx->Driver.DeleteTexture)
         (*ctx->Driver.DeleteTexture)( ctx, ss->TexObjectList );
      /* this function removes from linked list too! */
      gl_free_texture_object(ss, ss->TexObjectList);
   }
   _mesa_DeleteHashTable(ss->TexObjects);

   FREE(ss);
}



/*
 * Initialize the nth light.  Note that the defaults for light 0 are
 * different than the other lights.
 */
static void init_light( struct gl_light *l, GLuint n )
{
   make_empty_list( l );

   ASSIGN_4V( l->Ambient, 0.0, 0.0, 0.0, 1.0 );
   if (n==0) {
      ASSIGN_4V( l->Diffuse, 1.0, 1.0, 1.0, 1.0 );
      ASSIGN_4V( l->Specular, 1.0, 1.0, 1.0, 1.0 );
   }
   else {
      ASSIGN_4V( l->Diffuse, 0.0, 0.0, 0.0, 1.0 );
      ASSIGN_4V( l->Specular, 0.0, 0.0, 0.0, 1.0 );
   }
   ASSIGN_4V( l->EyePosition, 0.0, 0.0, 1.0, 0.0 );
   ASSIGN_3V( l->EyeDirection, 0.0, 0.0, -1.0 );
   l->SpotExponent = 0.0;
   gl_compute_spot_exp_table( l );
   l->SpotCutoff = 180.0;
   l->CosCutoff = 0.0;		/* KW: -ve values not admitted */
   l->ConstantAttenuation = 1.0;
   l->LinearAttenuation = 0.0;
   l->QuadraticAttenuation = 0.0;
   l->Enabled = GL_FALSE;
}



static void init_lightmodel( struct gl_lightmodel *lm )
{
   ASSIGN_4V( lm->Ambient, 0.2, 0.2, 0.2, 1.0 );
   lm->LocalViewer = GL_FALSE;
   lm->TwoSide = GL_FALSE;
   lm->ColorControl = GL_SINGLE_COLOR;
}


static void init_material( struct gl_material *m )
{
   ASSIGN_4V( m->Ambient,  0.2, 0.2, 0.2, 1.0 );
   ASSIGN_4V( m->Diffuse,  0.8, 0.8, 0.8, 1.0 );
   ASSIGN_4V( m->Specular, 0.0, 0.0, 0.0, 1.0 );
   ASSIGN_4V( m->Emission, 0.0, 0.0, 0.0, 1.0 );
   m->Shininess = 0.0;
   m->AmbientIndex = 0;
   m->DiffuseIndex = 1;
   m->SpecularIndex = 1;
}



static void init_texture_unit( GLcontext *ctx, GLuint unit )
{
   struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];

   texUnit->EnvMode = GL_MODULATE;
   ASSIGN_4V( texUnit->EnvColor, 0.0, 0.0, 0.0, 0.0 );
   texUnit->TexGenEnabled = 0;
   texUnit->GenModeS = GL_EYE_LINEAR;
   texUnit->GenModeT = GL_EYE_LINEAR;
   texUnit->GenModeR = GL_EYE_LINEAR;
   texUnit->GenModeQ = GL_EYE_LINEAR;
   /* Yes, these plane coefficients are correct! */
   ASSIGN_4V( texUnit->ObjectPlaneS, 1.0, 0.0, 0.0, 0.0 );
   ASSIGN_4V( texUnit->ObjectPlaneT, 0.0, 1.0, 0.0, 0.0 );
   ASSIGN_4V( texUnit->ObjectPlaneR, 0.0, 0.0, 0.0, 0.0 );
   ASSIGN_4V( texUnit->ObjectPlaneQ, 0.0, 0.0, 0.0, 0.0 );
   ASSIGN_4V( texUnit->EyePlaneS, 1.0, 0.0, 0.0, 0.0 );
   ASSIGN_4V( texUnit->EyePlaneT, 0.0, 1.0, 0.0, 0.0 );
   ASSIGN_4V( texUnit->EyePlaneR, 0.0, 0.0, 0.0, 0.0 );
   ASSIGN_4V( texUnit->EyePlaneQ, 0.0, 0.0, 0.0, 0.0 );

   texUnit->CurrentD[1] = ctx->Shared->DefaultD[1];
   texUnit->CurrentD[2] = ctx->Shared->DefaultD[2];
   texUnit->CurrentD[3] = ctx->Shared->DefaultD[3];
}


static void init_fallback_arrays( GLcontext *ctx )
{
   struct gl_client_array *cl;
   GLuint i;

   cl = &ctx->Fallback.Normal;
   cl->Size = 3;
   cl->Type = GL_FLOAT;
   cl->Stride = 0;
   cl->StrideB = 0;
   cl->Ptr = (void *) ctx->Current.Normal;
   cl->Enabled = 1;

   cl = &ctx->Fallback.Color;
   cl->Size = 4;
   cl->Type = GL_UNSIGNED_BYTE;
   cl->Stride = 0;
   cl->StrideB = 0;
   cl->Ptr = (void *) ctx->Current.ByteColor;
   cl->Enabled = 1;

   cl = &ctx->Fallback.Index;
   cl->Size = 1;
   cl->Type = GL_UNSIGNED_INT;
   cl->Stride = 0;
   cl->StrideB = 0;
   cl->Ptr = (void *) &ctx->Current.Index;
   cl->Enabled = 1;

   for (i = 0 ; i < MAX_TEXTURE_UNITS ; i++) {
      cl = &ctx->Fallback.TexCoord[i];
      cl->Size = 4;
      cl->Type = GL_FLOAT;
      cl->Stride = 0;
      cl->StrideB = 0;
      cl->Ptr = (void *) ctx->Current.Texcoord[i];
      cl->Enabled = 1;
   }

   cl = &ctx->Fallback.EdgeFlag;
   cl->Size = 1;
   cl->Type = GL_UNSIGNED_BYTE;
   cl->Stride = 0;
   cl->StrideB = 0;
   cl->Ptr = (void *) &ctx->Current.EdgeFlag;
   cl->Enabled = 1;
}


/* Initialize a 1-D evaluator map */
static void init_1d_map( struct gl_1d_map *map, int n, const float *initial )
{
   map->Order = 1;
   map->u1 = 0.0;
   map->u2 = 1.0;
   map->Points = (GLfloat *) MALLOC(n * sizeof(GLfloat));
   if (map->Points) {
      GLint i;
      for (i=0;i<n;i++)
         map->Points[i] = initial[i];
   }
}


/* Initialize a 2-D evaluator map */
static void init_2d_map( struct gl_2d_map *map, int n, const float *initial )
{
   map->Uorder = 1;
   map->Vorder = 1;
   map->u1 = 0.0;
   map->u2 = 1.0;
   map->v1 = 0.0;
   map->v2 = 1.0;
   map->Points = (GLfloat *) MALLOC(n * sizeof(GLfloat));
   if (map->Points) {
      GLint i;
      for (i=0;i<n;i++)
         map->Points[i] = initial[i];
   }
}


static void init_color_table( struct gl_color_table *p )
{
   p->Table[0] = 255;
   p->Table[1] = 255;
   p->Table[2] = 255;
   p->Table[3] = 255;
   p->Size = 1;
   p->IntFormat = GL_RGBA;
   p->Format = GL_RGBA;
}


/*
 * Initialize the attribute groups in a GLcontext.
 */
static void init_attrib_groups( GLcontext *ctx )
{
   GLuint i, j;

   assert(ctx);

   /* Constants, may be overriden by device drivers */
   ctx->Const.MaxTextureLevels = MAX_TEXTURE_LEVELS;
   ctx->Const.MaxTextureSize = 1 << (MAX_TEXTURE_LEVELS - 1);
   ctx->Const.MaxTextureUnits = MAX_TEXTURE_UNITS;
   ctx->Const.MaxArrayLockSize = MAX_ARRAY_LOCK_SIZE;
   ctx->Const.SubPixelBits = SUB_PIXEL_BITS;
   ctx->Const.MinPointSize = MIN_POINT_SIZE;
   ctx->Const.MaxPointSize = MAX_POINT_SIZE;
   ctx->Const.MinPointSizeAA = MIN_POINT_SIZE;
   ctx->Const.MaxPointSizeAA = MAX_POINT_SIZE;
   ctx->Const.PointSizeGranularity = POINT_SIZE_GRANULARITY;
   ctx->Const.MinLineWidth = MIN_LINE_WIDTH;
   ctx->Const.MaxLineWidth = MAX_LINE_WIDTH;
   ctx->Const.MinLineWidthAA = MIN_LINE_WIDTH;
   ctx->Const.MaxLineWidthAA = MAX_LINE_WIDTH;
   ctx->Const.LineWidthGranularity = LINE_WIDTH_GRANULARITY;
   ctx->Const.NumAuxBuffers = NUM_AUX_BUFFERS;

   /* Modelview matrix */
   gl_matrix_ctr( &ctx->ModelView );
   gl_matrix_alloc_inv( &ctx->ModelView );

   ctx->ModelViewStackDepth = 0;
   for (i = 0; i < MAX_MODELVIEW_STACK_DEPTH - 1; i++) {
      gl_matrix_ctr( &ctx->ModelViewStack[i] );
      gl_matrix_alloc_inv( &ctx->ModelViewStack[i] );
   }

   /* Projection matrix - need inv for user clipping in clip space*/
   gl_matrix_ctr( &ctx->ProjectionMatrix );
   gl_matrix_alloc_inv( &ctx->ProjectionMatrix );

   gl_matrix_ctr( &ctx->ModelProjectMatrix );
   gl_matrix_ctr( &ctx->ModelProjectWinMatrix );
   ctx->ModelProjectWinMatrixUptodate = GL_FALSE;

   ctx->ProjectionStackDepth = 0;
   ctx->NearFarStack[0][0] = 1.0; /* These values seem weird by make */
   ctx->NearFarStack[0][1] = 0.0; /* sense mathematically. */

   for (i = 0; i < MAX_PROJECTION_STACK_DEPTH - 1; i++) {
      gl_matrix_ctr( &ctx->ProjectionStack[i] );
      gl_matrix_alloc_inv( &ctx->ProjectionStack[i] );
   }

   /* Texture matrix */
   for (i=0; i<MAX_TEXTURE_UNITS; i++) {
      gl_matrix_ctr( &ctx->TextureMatrix[i] );
      ctx->TextureStackDepth[i] = 0;
      for (j = 0; j < MAX_TEXTURE_STACK_DEPTH - 1; j++) {
         ctx->TextureStack[i][j].inv = 0;
      }
   }

   /* Accumulate buffer group */
   ASSIGN_4V( ctx->Accum.ClearColor, 0.0, 0.0, 0.0, 0.0 );

   /* Color buffer group */
   ctx->Color.IndexMask = 0xffffffff;
   ctx->Color.ColorMask[0] = 0xff;
   ctx->Color.ColorMask[1] = 0xff;
   ctx->Color.ColorMask[2] = 0xff;
   ctx->Color.ColorMask[3] = 0xff;
   ctx->Color.SWmasking = GL_FALSE;
   ctx->Color.ClearIndex = 0;
   ASSIGN_4V( ctx->Color.ClearColor, 0.0, 0.0, 0.0, 0.0 );
   ctx->Color.DrawBuffer = GL_FRONT;
   ctx->Color.AlphaEnabled = GL_FALSE;
   ctx->Color.AlphaFunc = GL_ALWAYS;
   ctx->Color.AlphaRef = 0;
   ctx->Color.BlendEnabled = GL_FALSE;
   ctx->Color.BlendSrcRGB = GL_ONE;
   ctx->Color.BlendDstRGB = GL_ZERO;
   ctx->Color.BlendSrcA = GL_ONE;
   ctx->Color.BlendDstA = GL_ZERO;
   ctx->Color.BlendEquation = GL_FUNC_ADD_EXT;
   ctx->Color.BlendFunc = NULL;  /* this pointer set only when needed */
   ASSIGN_4V( ctx->Color.BlendColor, 0.0, 0.0, 0.0, 0.0 );
   ctx->Color.IndexLogicOpEnabled = GL_FALSE;
   ctx->Color.ColorLogicOpEnabled = GL_FALSE;
   ctx->Color.SWLogicOpEnabled = GL_FALSE;
   ctx->Color.LogicOp = GL_COPY;
   ctx->Color.DitherFlag = GL_TRUE;
   ctx->Color.MultiDrawBuffer = GL_FALSE;

   /* Current group */
   ASSIGN_4V( ctx->Current.ByteColor, 255, 255, 255, 255);
   ctx->Current.Index = 1;
   for (i=0; i<MAX_TEXTURE_UNITS; i++)
      ASSIGN_4V( ctx->Current.Texcoord[i], 0.0, 0.0, 0.0, 1.0 );
   ASSIGN_4V( ctx->Current.RasterPos, 0.0, 0.0, 0.0, 1.0 );
   ctx->Current.RasterDistance = 0.0;
   ASSIGN_4V( ctx->Current.RasterColor, 1.0, 1.0, 1.0, 1.0 );
   ctx->Current.RasterIndex = 1;
   for (i=0; i<MAX_TEXTURE_UNITS; i++)
      ASSIGN_4V( ctx->Current.RasterMultiTexCoord[i], 0.0, 0.0, 0.0, 1.0 );
   ctx->Current.RasterTexCoord = ctx->Current.RasterMultiTexCoord[0];
   ctx->Current.RasterPosValid = GL_TRUE;
   ctx->Current.EdgeFlag = GL_TRUE;
   ASSIGN_3V( ctx->Current.Normal, 0.0, 0.0, 1.0 );
   ctx->Current.Primitive = (GLenum) (GL_POLYGON + 1);

   ctx->Current.Flag = (VERT_NORM|VERT_INDEX|VERT_RGBA|VERT_EDGE|
                        VERT_TEX0_1|VERT_TEX1_1|VERT_MATERIAL);

   init_fallback_arrays( ctx );

   /* Depth buffer group */
   ctx->Depth.Test = GL_FALSE;
   ctx->Depth.Clear = 1.0;
   ctx->Depth.Func = GL_LESS;
   ctx->Depth.Mask = GL_TRUE;
   ctx->Depth.OcclusionTest = GL_FALSE;

   /* Evaluators group */
   ctx->Eval.Map1Color4 = GL_FALSE;
   ctx->Eval.Map1Index = GL_FALSE;
   ctx->Eval.Map1Normal = GL_FALSE;
   ctx->Eval.Map1TextureCoord1 = GL_FALSE;
   ctx->Eval.Map1TextureCoord2 = GL_FALSE;
   ctx->Eval.Map1TextureCoord3 = GL_FALSE;
   ctx->Eval.Map1TextureCoord4 = GL_FALSE;
   ctx->Eval.Map1Vertex3 = GL_FALSE;
   ctx->Eval.Map1Vertex4 = GL_FALSE;
   ctx->Eval.Map2Color4 = GL_FALSE;
   ctx->Eval.Map2Index = GL_FALSE;
   ctx->Eval.Map2Normal = GL_FALSE;
   ctx->Eval.Map2TextureCoord1 = GL_FALSE;
   ctx->Eval.Map2TextureCoord2 = GL_FALSE;
   ctx->Eval.Map2TextureCoord3 = GL_FALSE;
   ctx->Eval.Map2TextureCoord4 = GL_FALSE;
   ctx->Eval.Map2Vertex3 = GL_FALSE;
   ctx->Eval.Map2Vertex4 = GL_FALSE;
   ctx->Eval.AutoNormal = GL_FALSE;
   ctx->Eval.MapGrid1un = 1;
   ctx->Eval.MapGrid1u1 = 0.0;
   ctx->Eval.MapGrid1u2 = 1.0;
   ctx->Eval.MapGrid2un = 1;
   ctx->Eval.MapGrid2vn = 1;
   ctx->Eval.MapGrid2u1 = 0.0;
   ctx->Eval.MapGrid2u2 = 1.0;
   ctx->Eval.MapGrid2v1 = 0.0;
   ctx->Eval.MapGrid2v2 = 1.0;

   /* Evaluator data */
   {
      static GLfloat vertex[4] = { 0.0, 0.0, 0.0, 1.0 };
      static GLfloat normal[3] = { 0.0, 0.0, 1.0 };
      static GLfloat index[1] = { 1.0 };
      static GLfloat color[4] = { 1.0, 1.0, 1.0, 1.0 };
      static GLfloat texcoord[4] = { 0.0, 0.0, 0.0, 1.0 };

      init_1d_map( &ctx->EvalMap.Map1Vertex3, 3, vertex );
      init_1d_map( &ctx->EvalMap.Map1Vertex4, 4, vertex );
      init_1d_map( &ctx->EvalMap.Map1Index, 1, index );
      init_1d_map( &ctx->EvalMap.Map1Color4, 4, color );
      init_1d_map( &ctx->EvalMap.Map1Normal, 3, normal );
      init_1d_map( &ctx->EvalMap.Map1Texture1, 1, texcoord );
      init_1d_map( &ctx->EvalMap.Map1Texture2, 2, texcoord );
      init_1d_map( &ctx->EvalMap.Map1Texture3, 3, texcoord );
      init_1d_map( &ctx->EvalMap.Map1Texture4, 4, texcoord );

      init_2d_map( &ctx->EvalMap.Map2Vertex3, 3, vertex );
      init_2d_map( &ctx->EvalMap.Map2Vertex4, 4, vertex );
      init_2d_map( &ctx->EvalMap.Map2Index, 1, index );
      init_2d_map( &ctx->EvalMap.Map2Color4, 4, color );
      init_2d_map( &ctx->EvalMap.Map2Normal, 3, normal );
      init_2d_map( &ctx->EvalMap.Map2Texture1, 1, texcoord );
      init_2d_map( &ctx->EvalMap.Map2Texture2, 2, texcoord );
      init_2d_map( &ctx->EvalMap.Map2Texture3, 3, texcoord );
      init_2d_map( &ctx->EvalMap.Map2Texture4, 4, texcoord );
   }

   /* Fog group */
   ctx->Fog.Enabled = GL_FALSE;
   ctx->Fog.Mode = GL_EXP;
   ASSIGN_4V( ctx->Fog.Color, 0.0, 0.0, 0.0, 0.0 );
   ctx->Fog.Index = 0.0;
   ctx->Fog.Density = 1.0;
   ctx->Fog.Start = 0.0;
   ctx->Fog.End = 1.0;

   /* Hint group */
   ctx->Hint.PerspectiveCorrection = GL_DONT_CARE;
   ctx->Hint.PointSmooth = GL_DONT_CARE;
   ctx->Hint.LineSmooth = GL_DONT_CARE;
   ctx->Hint.PolygonSmooth = GL_DONT_CARE;
   ctx->Hint.Fog = GL_DONT_CARE;

   ctx->Hint.AllowDrawWin = GL_TRUE;
   ctx->Hint.AllowDrawSpn = GL_TRUE;
   ctx->Hint.AllowDrawMem = GL_TRUE;
   ctx->Hint.StrictLighting = GL_TRUE;

   /* Pipeline */
   gl_pipeline_init( ctx );
   gl_cva_init( ctx );

   /* Extensions */
   gl_extensions_ctr( ctx );

   ctx->AllowVertexCull = CLIP_CULLED_BIT;

   /* Lighting group */
   for (i=0;i<MAX_LIGHTS;i++) {
      init_light( &ctx->Light.Light[i], i );
   }
   make_empty_list( &ctx->Light.EnabledList );

   init_lightmodel( &ctx->Light.Model );
   init_material( &ctx->Light.Material[0] );
   init_material( &ctx->Light.Material[1] );
   ctx->Light.ShadeModel = GL_SMOOTH;
   ctx->Light.Enabled = GL_FALSE;
   ctx->Light.ColorMaterialFace = GL_FRONT_AND_BACK;
   ctx->Light.ColorMaterialMode = GL_AMBIENT_AND_DIFFUSE;
   ctx->Light.ColorMaterialBitmask
      = gl_material_bitmask( ctx,
                             GL_FRONT_AND_BACK,
                             GL_AMBIENT_AND_DIFFUSE, ~0, 0 );

   ctx->Light.ColorMaterialEnabled = GL_FALSE;

   /* Lighting miscellaneous */
   ctx->ShineTabList = MALLOC_STRUCT( gl_shine_tab );
   make_empty_list( ctx->ShineTabList );
   for (i = 0 ; i < 10 ; i++) {
      struct gl_shine_tab *s = MALLOC_STRUCT( gl_shine_tab );
      s->shininess = -1;
      s->refcount = 0;
      insert_at_tail( ctx->ShineTabList, s );
   }
   for (i = 0 ; i < 4 ; i++) {
      ctx->ShineTable[i] = ctx->ShineTabList->prev;
      ctx->ShineTable[i]->refcount++;
   }


   /* Line group */
   ctx->Line.SmoothFlag = GL_FALSE;
   ctx->Line.StippleFlag = GL_FALSE;
   ctx->Line.Width = 1.0;
   ctx->Line.StipplePattern = 0xffff;
   ctx->Line.StippleFactor = 1;

   /* Display List group */
   ctx->List.ListBase = 0;

   /* Pixel group */
   ctx->Pixel.RedBias = 0.0;
   ctx->Pixel.RedScale = 1.0;
   ctx->Pixel.GreenBias = 0.0;
   ctx->Pixel.GreenScale = 1.0;
   ctx->Pixel.BlueBias = 0.0;
   ctx->Pixel.BlueScale = 1.0;
   ctx->Pixel.AlphaBias = 0.0;
   ctx->Pixel.AlphaScale = 1.0;
   ctx->Pixel.ScaleOrBiasRGBA = GL_FALSE;
   ctx->Pixel.DepthBias = 0.0;
   ctx->Pixel.DepthScale = 1.0;
   ctx->Pixel.IndexOffset = 0;
   ctx->Pixel.IndexShift = 0;
   ctx->Pixel.ZoomX = 1.0;
   ctx->Pixel.ZoomY = 1.0;
   ctx->Pixel.MapColorFlag = GL_FALSE;
   ctx->Pixel.MapStencilFlag = GL_FALSE;
   ctx->Pixel.MapStoSsize = 1;
   ctx->Pixel.MapItoIsize = 1;
   ctx->Pixel.MapItoRsize = 1;
   ctx->Pixel.MapItoGsize = 1;
   ctx->Pixel.MapItoBsize = 1;
   ctx->Pixel.MapItoAsize = 1;
   ctx->Pixel.MapRtoRsize = 1;
   ctx->Pixel.MapGtoGsize = 1;
   ctx->Pixel.MapBtoBsize = 1;
   ctx->Pixel.MapAtoAsize = 1;
   ctx->Pixel.MapStoS[0] = 0;
   ctx->Pixel.MapItoI[0] = 0;
   ctx->Pixel.MapItoR[0] = 0.0;
   ctx->Pixel.MapItoG[0] = 0.0;
   ctx->Pixel.MapItoB[0] = 0.0;
   ctx->Pixel.MapItoA[0] = 0.0;
   ctx->Pixel.MapItoR8[0] = 0;
   ctx->Pixel.MapItoG8[0] = 0;
   ctx->Pixel.MapItoB8[0] = 0;
   ctx->Pixel.MapItoA8[0] = 0;
   ctx->Pixel.MapRtoR[0] = 0.0;
   ctx->Pixel.MapGtoG[0] = 0.0;
   ctx->Pixel.MapBtoB[0] = 0.0;
   ctx->Pixel.MapAtoA[0] = 0.0;

   /* Point group */
   ctx->Point.SmoothFlag = GL_FALSE;
   ctx->Point.Size = 1.0;
   ctx->Point.Params[0] = 1.0;
   ctx->Point.Params[1] = 0.0;
   ctx->Point.Params[2] = 0.0;
   ctx->Point.Attenuated = GL_FALSE;
   ctx->Point.MinSize = 0.0;
   ctx->Point.MaxSize = (GLfloat) MAX_POINT_SIZE;
   ctx->Point.Threshold = 1.0;

   /* Polygon group */
   ctx->Polygon.CullFlag = GL_FALSE;
   ctx->Polygon.CullFaceMode = GL_BACK;
   ctx->Polygon.FrontFace = GL_CCW;
   ctx->Polygon.FrontBit = 0;
   ctx->Polygon.FrontMode = GL_FILL;
   ctx->Polygon.BackMode = GL_FILL;
   ctx->Polygon.Unfilled = GL_FALSE;
   ctx->Polygon.SmoothFlag = GL_FALSE;
   ctx->Polygon.StippleFlag = GL_FALSE;
   ctx->Polygon.OffsetFactor = 0.0F;
   ctx->Polygon.OffsetUnits = 0.0F;
   ctx->Polygon.OffsetPoint = GL_FALSE;
   ctx->Polygon.OffsetLine = GL_FALSE;
   ctx->Polygon.OffsetFill = GL_FALSE;

   /* Polygon Stipple group */
   MEMSET( ctx->PolygonStipple, 0xff, 32*sizeof(GLuint) );

   /* Scissor group */
   ctx->Scissor.Enabled = GL_FALSE;
   ctx->Scissor.X = 0;
   ctx->Scissor.Y = 0;
   ctx->Scissor.Width = 0;
   ctx->Scissor.Height = 0;

   /* Stencil group */
   ctx->Stencil.Enabled = GL_FALSE;
   ctx->Stencil.Function = GL_ALWAYS;
   ctx->Stencil.FailFunc = GL_KEEP;
   ctx->Stencil.ZPassFunc = GL_KEEP;
   ctx->Stencil.ZFailFunc = GL_KEEP;
   ctx->Stencil.Ref = 0;
   ctx->Stencil.ValueMask = STENCIL_MAX;
   ctx->Stencil.Clear = 0;
   ctx->Stencil.WriteMask = STENCIL_MAX;

   /* Texture group */
   ctx->Texture.CurrentUnit = 0;      /* multitexture */
   ctx->Texture.CurrentTransformUnit = 0; /* multitexture */
   ctx->Texture.Enabled = 0;
   for (i=0; i<MAX_TEXTURE_UNITS; i++)
      init_texture_unit( ctx, i );
   init_color_table(&ctx->Texture.Palette);

   /* Transformation group */
   ctx->Transform.MatrixMode = GL_MODELVIEW;
   ctx->Transform.Normalize = GL_FALSE;
   ctx->Transform.RescaleNormals = GL_FALSE;
   for (i=0;i<MAX_CLIP_PLANES;i++) {
      ctx->Transform.ClipEnabled[i] = GL_FALSE;
      ASSIGN_4V( ctx->Transform.EyeUserPlane[i], 0.0, 0.0, 0.0, 0.0 );
   }
   ctx->Transform.AnyClip = GL_FALSE;

   /* Viewport group */
   ctx->Viewport.X = 0;
   ctx->Viewport.Y = 0;
   ctx->Viewport.Width = 0;
   ctx->Viewport.Height = 0;
   ctx->Viewport.Near = 0.0;
   ctx->Viewport.Far = 1.0;
   gl_matrix_ctr(&ctx->Viewport.WindowMap);

#define Sz 10
#define Tz 14
   ctx->Viewport.WindowMap.m[Sz] = 0.5 * ctx->Visual->DepthMaxF;
   ctx->Viewport.WindowMap.m[Tz] = 0.5 * ctx->Visual->DepthMaxF;
#undef Sz
#undef Tz

   ctx->Viewport.WindowMap.flags = MAT_FLAG_GENERAL_SCALE|MAT_FLAG_TRANSLATION;
   ctx->Viewport.WindowMap.type = MATRIX_3D_NO_ROT;

   /* Vertex arrays */
   ctx->Array.Vertex.Size = 4;
   ctx->Array.Vertex.Type = GL_FLOAT;
   ctx->Array.Vertex.Stride = 0;
   ctx->Array.Vertex.StrideB = 0;
   ctx->Array.Vertex.Ptr = NULL;
   ctx->Array.Vertex.Enabled = GL_FALSE;
   ctx->Array.Normal.Type = GL_FLOAT;
   ctx->Array.Normal.Stride = 0;
   ctx->Array.Normal.StrideB = 0;
   ctx->Array.Normal.Ptr = NULL;
   ctx->Array.Normal.Enabled = GL_FALSE;
   ctx->Array.Color.Size = 4;
   ctx->Array.Color.Type = GL_FLOAT;
   ctx->Array.Color.Stride = 0;
   ctx->Array.Color.StrideB = 0;
   ctx->Array.Color.Ptr = NULL;
   ctx->Array.Color.Enabled = GL_FALSE;
   ctx->Array.Index.Type = GL_FLOAT;
   ctx->Array.Index.Stride = 0;
   ctx->Array.Index.StrideB = 0;
   ctx->Array.Index.Ptr = NULL;
   ctx->Array.Index.Enabled = GL_FALSE;
   for (i = 0; i < MAX_TEXTURE_UNITS; i++) {
      ctx->Array.TexCoord[i].Size = 4;
      ctx->Array.TexCoord[i].Type = GL_FLOAT;
      ctx->Array.TexCoord[i].Stride = 0;
      ctx->Array.TexCoord[i].StrideB = 0;
      ctx->Array.TexCoord[i].Ptr = NULL;
      ctx->Array.TexCoord[i].Enabled = GL_FALSE;
   }
   ctx->Array.TexCoordInterleaveFactor = 1;
   ctx->Array.EdgeFlag.Stride = 0;
   ctx->Array.EdgeFlag.StrideB = 0;
   ctx->Array.EdgeFlag.Ptr = NULL;
   ctx->Array.EdgeFlag.Enabled = GL_FALSE;
   ctx->Array.ActiveTexture = 0;   /* GL_ARB_multitexture */

   /* Pixel transfer */
   ctx->Pack.Alignment = 4;
   ctx->Pack.RowLength = 0;
   ctx->Pack.ImageHeight = 0;
   ctx->Pack.SkipPixels = 0;
   ctx->Pack.SkipRows = 0;
   ctx->Pack.SkipImages = 0;
   ctx->Pack.SwapBytes = GL_FALSE;
   ctx->Pack.LsbFirst = GL_FALSE;
   ctx->Unpack.Alignment = 4;
   ctx->Unpack.RowLength = 0;
   ctx->Unpack.ImageHeight = 0;
   ctx->Unpack.SkipPixels = 0;
   ctx->Unpack.SkipRows = 0;
   ctx->Unpack.SkipImages = 0;
   ctx->Unpack.SwapBytes = GL_FALSE;
   ctx->Unpack.LsbFirst = GL_FALSE;

   /* Feedback */
   ctx->Feedback.Type = GL_2D;   /* TODO: verify */
   ctx->Feedback.Buffer = NULL;
   ctx->Feedback.BufferSize = 0;
   ctx->Feedback.Count = 0;

   /* Selection/picking */
   ctx->Select.Buffer = NULL;
   ctx->Select.BufferSize = 0;
   ctx->Select.BufferCount = 0;
   ctx->Select.Hits = 0;
   ctx->Select.NameStackDepth = 0;

   /* Optimized Accum buffer */
   ctx->IntegerAccumMode = GL_TRUE;
   ctx->IntegerAccumScaler = 0.0;

   /* Renderer and client attribute stacks */
   ctx->AttribStackDepth = 0;
   ctx->ClientAttribStackDepth = 0;

   /* Miscellaneous */
   ctx->NewState = NEW_ALL;
   ctx->RenderMode = GL_RENDER;
   ctx->StippleCounter = 0;
   ctx->NeedNormals = GL_FALSE;
   ctx->DoViewportMapping = GL_TRUE;

   ctx->NeedEyeCoords = GL_FALSE;
   ctx->NeedEyeNormals = GL_FALSE;
   ctx->vb_proj_matrix = &ctx->ModelProjectMatrix;

   /* Display list */
   ctx->CallDepth = 0;
   ctx->ExecuteFlag = GL_TRUE;
   ctx->CompileFlag = GL_FALSE;
   ctx->CurrentListPtr = NULL;
   ctx->CurrentBlock = NULL;
   ctx->CurrentListNum = 0;
   ctx->CurrentPos = 0;

   ctx->ErrorValue = (GLenum) GL_NO_ERROR;

   ctx->CatchSignals = GL_TRUE;
   ctx->OcclusionResult = GL_FALSE;

   /* For debug/development only */
   ctx->NoRaster = getenv("MESA_NO_RASTER") ? GL_TRUE : GL_FALSE;
   ctx->FirstTimeCurrent = GL_TRUE;

   /* Dither disable */
   ctx->NoDither = getenv("MESA_NO_DITHER") ? GL_TRUE : GL_FALSE;
   if (ctx->NoDither) {
      if (getenv("MESA_DEBUG")) {
         fprintf(stderr, "MESA_NO_DITHER set - dithering disabled\n");
      }
      ctx->Color.DitherFlag = GL_FALSE;
   }
}




/*
 * Allocate the proxy textures.  If we run out of memory part way through
 * the allocations clean up and return GL_FALSE.
 * Return:  GL_TRUE=success, GL_FALSE=failure
 */
static GLboolean alloc_proxy_textures( GLcontext *ctx )
{
   GLboolean out_of_memory;
   GLint i;

   ctx->Texture.Proxy1D = gl_alloc_texture_object(NULL, 0, 1);
   if (!ctx->Texture.Proxy1D) {
      return GL_FALSE;
   }

   ctx->Texture.Proxy2D = gl_alloc_texture_object(NULL, 0, 2);
   if (!ctx->Texture.Proxy2D) {
      gl_free_texture_object(NULL, ctx->Texture.Proxy1D);
      return GL_FALSE;
   }

   ctx->Texture.Proxy3D = gl_alloc_texture_object(NULL, 0, 3);
   if (!ctx->Texture.Proxy3D) {
      gl_free_texture_object(NULL, ctx->Texture.Proxy1D);
      gl_free_texture_object(NULL, ctx->Texture.Proxy2D);
      return GL_FALSE;
   }

   out_of_memory = GL_FALSE;
   for (i=0;i<MAX_TEXTURE_LEVELS;i++) {
      ctx->Texture.Proxy1D->Image[i] = _mesa_alloc_texture_image();
      ctx->Texture.Proxy2D->Image[i] = _mesa_alloc_texture_image();
      ctx->Texture.Proxy3D->Image[i] = _mesa_alloc_texture_image();
      if (!ctx->Texture.Proxy1D->Image[i]
          || !ctx->Texture.Proxy2D->Image[i]
          || !ctx->Texture.Proxy3D->Image[i]) {
         out_of_memory = GL_TRUE;
      }
   }
   if (out_of_memory) {
      for (i=0;i<MAX_TEXTURE_LEVELS;i++) {
         if (ctx->Texture.Proxy1D->Image[i]) {
            _mesa_free_texture_image(ctx->Texture.Proxy1D->Image[i]);
         }
         if (ctx->Texture.Proxy2D->Image[i]) {
            _mesa_free_texture_image(ctx->Texture.Proxy2D->Image[i]);
         }
         if (ctx->Texture.Proxy3D->Image[i]) {
            _mesa_free_texture_image(ctx->Texture.Proxy3D->Image[i]);
         }
      }
      gl_free_texture_object(NULL, ctx->Texture.Proxy1D);
      gl_free_texture_object(NULL, ctx->Texture.Proxy2D);
      gl_free_texture_object(NULL, ctx->Texture.Proxy3D);
      return GL_FALSE;
   }
   else {
      return GL_TRUE;
   }
}



/*
 * Initialize a GLcontext struct.
 */
GLboolean gl_initialize_context_data( GLcontext *ctx,
                                      GLvisual *visual,
                                      GLcontext *share_list,
                                      void *driver_ctx,
                                      GLboolean direct )
{
   (void) direct;  /* not used */

   /* misc one-time initializations */
   one_time_init();

   ctx->DriverCtx = driver_ctx;
   ctx->Visual = visual;
   ctx->DrawBuffer = NULL;
   ctx->ReadBuffer = NULL;

   ctx->VB = gl_vb_create_for_immediate( ctx );
   if (!ctx->VB) {
      FREE( ctx );
      return GL_FALSE;
   }
   ctx->input = ctx->VB->IM;

   ctx->PB = gl_alloc_pb();
   if (!ctx->PB) {
      FREE( ctx->VB );
      FREE( ctx );
      return GL_FALSE;
   }

   if (share_list) {
      /* share the group of display lists of another context */
      ctx->Shared = share_list->Shared;
   }
   else {
      /* allocate new group of display lists */
      ctx->Shared = alloc_shared_state();
      if (!ctx->Shared) {
         FREE(ctx->VB);
         FREE(ctx->PB);
         FREE(ctx);
         return GL_FALSE;
      }
   }
   _glthread_LOCK_MUTEX(ctx->Shared->Mutex);
   ctx->Shared->RefCount++;
   _glthread_UNLOCK_MUTEX(ctx->Shared->Mutex);

   init_attrib_groups( ctx );

   gl_reset_vb( ctx->VB );
   gl_reset_input( ctx );

   if (visual->DBflag) {
      ctx->Color.DrawBuffer = GL_BACK;
      ctx->Color.DriverDrawBuffer = GL_BACK_LEFT;
      ctx->Color.DrawDestMask = BACK_LEFT_BIT;
      ctx->Pixel.ReadBuffer = GL_BACK;
      ctx->Pixel.DriverReadBuffer = GL_BACK_LEFT;
   }
   else {
      ctx->Color.DrawBuffer = GL_FRONT;
      ctx->Color.DriverDrawBuffer = GL_FRONT_LEFT;
      ctx->Color.DrawDestMask = FRONT_LEFT_BIT;
      ctx->Pixel.ReadBuffer = GL_FRONT;
      ctx->Pixel.DriverReadBuffer = GL_FRONT_LEFT;
   }

#ifdef PROFILE
   init_timings( ctx );
#endif

   if (!alloc_proxy_textures(ctx)) {
      free_shared_state(ctx, ctx->Shared);
      FREE(ctx->VB);
      FREE(ctx->PB);
      FREE(ctx);
      return GL_FALSE;
   }

   /* setup API dispatch tables */
   ctx->Exec = (struct _glapi_table *) CALLOC(_glapi_get_dispatch_table_size() * sizeof(void *));
   ctx->Save = (struct _glapi_table *) CALLOC(_glapi_get_dispatch_table_size() * sizeof(void *));
   if (!ctx->Exec || !ctx->Save) {
      free_shared_state(ctx, ctx->Shared);
      FREE(ctx->VB);
      FREE(ctx->PB);
      if (ctx->Exec)
         FREE(ctx->Exec);
      FREE(ctx);
   }
   _mesa_init_exec_table( ctx->Exec );
   _mesa_init_dlist_table( ctx->Save );
   ctx->CurrentDispatch = ctx->Exec;

   return GL_TRUE;
}



/*
 * Allocate and initialize a GLcontext structure.
 * Input:  visual - a GLvisual pointer
 *         sharelist - another context to share display lists with or NULL
 *         driver_ctx - pointer to device driver's context state struct
 * Return:  pointer to a new gl_context struct or NULL if error.
 */
GLcontext *gl_create_context( GLvisual *visual,
                              GLcontext *share_list,
                              void *driver_ctx,
                              GLboolean direct )
{
   GLcontext *ctx = (GLcontext *) CALLOC( sizeof(GLcontext) );
   if (!ctx) {
      return NULL;
   }

   if (gl_initialize_context_data(ctx, visual, share_list,
                                  driver_ctx, direct)) {
      return ctx;
   }
   else {
      FREE(ctx);
      return NULL;
   }
}



/*
 * Free the data associated with the given context.
 * But don't free() the GLcontext struct itself!
 */
void gl_free_context_data( GLcontext *ctx )
{
   struct gl_shine_tab *s, *tmps;
   GLuint i, j;

   /* if we're destroying the current context, unbind it first */
   if (ctx == gl_get_current_context()) {
      gl_make_current(NULL, NULL);
   }

#ifdef PROFILE
   if (getenv("MESA_PROFILE")) {
      print_timings( ctx );
   }
#endif

   gl_matrix_dtr( &ctx->ModelView );
   for (i = 0; i < MAX_MODELVIEW_STACK_DEPTH - 1; i++) {
      gl_matrix_dtr( &ctx->ModelViewStack[i] );
   }
   gl_matrix_dtr( &ctx->ProjectionMatrix );
   for (i = 0; i < MAX_PROJECTION_STACK_DEPTH - 1; i++) {
      gl_matrix_dtr( &ctx->ProjectionStack[i] );
   }
   for (i = 0; i < MAX_TEXTURE_UNITS; i++) {
      gl_matrix_dtr( &ctx->TextureMatrix[i] );
      for (j = 0; j < MAX_TEXTURE_STACK_DEPTH - 1; j++) {
         gl_matrix_dtr( &ctx->TextureStack[i][j] );
      }
   }

   FREE( ctx->PB );

   if(ctx->input != ctx->VB->IM)
      gl_immediate_free( ctx->input );

   gl_vb_free( ctx->VB );

   _glthread_LOCK_MUTEX(ctx->Shared->Mutex);
   ctx->Shared->RefCount--;
   assert(ctx->Shared->RefCount >= 0);
   _glthread_UNLOCK_MUTEX(ctx->Shared->Mutex);
   if (ctx->Shared->RefCount == 0) {
      /* free shared state */
      free_shared_state( ctx, ctx->Shared );
   }

   foreach_s( s, tmps, ctx->ShineTabList ) {
      FREE( s );
   }
   FREE( ctx->ShineTabList );

   /* Free proxy texture objects */
   gl_free_texture_object( NULL, ctx->Texture.Proxy1D );
   gl_free_texture_object( NULL, ctx->Texture.Proxy2D );
   gl_free_texture_object( NULL, ctx->Texture.Proxy3D );

   /* Free evaluator data */
   if (ctx->EvalMap.Map1Vertex3.Points)
      FREE( ctx->EvalMap.Map1Vertex3.Points );
   if (ctx->EvalMap.Map1Vertex4.Points)
      FREE( ctx->EvalMap.Map1Vertex4.Points );
   if (ctx->EvalMap.Map1Index.Points)
      FREE( ctx->EvalMap.Map1Index.Points );
   if (ctx->EvalMap.Map1Color4.Points)
      FREE( ctx->EvalMap.Map1Color4.Points );
   if (ctx->EvalMap.Map1Normal.Points)
      FREE( ctx->EvalMap.Map1Normal.Points );
   if (ctx->EvalMap.Map1Texture1.Points)
      FREE( ctx->EvalMap.Map1Texture1.Points );
   if (ctx->EvalMap.Map1Texture2.Points)
      FREE( ctx->EvalMap.Map1Texture2.Points );
   if (ctx->EvalMap.Map1Texture3.Points)
      FREE( ctx->EvalMap.Map1Texture3.Points );
   if (ctx->EvalMap.Map1Texture4.Points)
      FREE( ctx->EvalMap.Map1Texture4.Points );

   if (ctx->EvalMap.Map2Vertex3.Points)
      FREE( ctx->EvalMap.Map2Vertex3.Points );
   if (ctx->EvalMap.Map2Vertex4.Points)
      FREE( ctx->EvalMap.Map2Vertex4.Points );
   if (ctx->EvalMap.Map2Index.Points)
      FREE( ctx->EvalMap.Map2Index.Points );
   if (ctx->EvalMap.Map2Color4.Points)
      FREE( ctx->EvalMap.Map2Color4.Points );
   if (ctx->EvalMap.Map2Normal.Points)
      FREE( ctx->EvalMap.Map2Normal.Points );
   if (ctx->EvalMap.Map2Texture1.Points)
      FREE( ctx->EvalMap.Map2Texture1.Points );
   if (ctx->EvalMap.Map2Texture2.Points)
      FREE( ctx->EvalMap.Map2Texture2.Points );
   if (ctx->EvalMap.Map2Texture3.Points)
      FREE( ctx->EvalMap.Map2Texture3.Points );
   if (ctx->EvalMap.Map2Texture4.Points)
      FREE( ctx->EvalMap.Map2Texture4.Points );

   /* Free cache of immediate buffers. */
   while (ctx->nr_im_queued-- > 0) {
      struct immediate * next = ctx->freed_im_queue->next;
      FREE( ctx->freed_im_queue );
      ctx->freed_im_queue = next;
   }
   gl_extensions_dtr(ctx);

   FREE(ctx->Exec);
   FREE(ctx->Save);
}



/*
 * Destroy a GLcontext structure.
 */
void gl_destroy_context( GLcontext *ctx )
{
   if (ctx) {
      gl_free_context_data(ctx);
      FREE( (void *) ctx );
   }
}



/*
 * Called by the driver after both the context and driver are fully
 * initialized.  Currently just reads the config file.
 */
void gl_context_initialize( GLcontext *ctx )
{
   gl_read_config_file( ctx );
}



/*
 * Copy attribute groups from one context to another.
 * Input:  src - source context
 *         dst - destination context
 *         mask - bitwise OR of GL_*_BIT flags
 */
void gl_copy_context( const GLcontext *src, GLcontext *dst, GLuint mask )
{
   if (mask & GL_ACCUM_BUFFER_BIT) {
      MEMCPY( &dst->Accum, &src->Accum, sizeof(struct gl_accum_attrib) );
   }
   if (mask & GL_COLOR_BUFFER_BIT) {
      MEMCPY( &dst->Color, &src->Color, sizeof(struct gl_colorbuffer_attrib) );
   }
   if (mask & GL_CURRENT_BIT) {
      MEMCPY( &dst->Current, &src->Current, sizeof(struct gl_current_attrib) );
   }
   if (mask & GL_DEPTH_BUFFER_BIT) {
      MEMCPY( &dst->Depth, &src->Depth, sizeof(struct gl_depthbuffer_attrib) );
   }
   if (mask & GL_ENABLE_BIT) {
      /* no op */
   }
   if (mask & GL_EVAL_BIT) {
      MEMCPY( &dst->Eval, &src->Eval, sizeof(struct gl_eval_attrib) );
   }
   if (mask & GL_FOG_BIT) {
      MEMCPY( &dst->Fog, &src->Fog, sizeof(struct gl_fog_attrib) );
   }
   if (mask & GL_HINT_BIT) {
      MEMCPY( &dst->Hint, &src->Hint, sizeof(struct gl_hint_attrib) );
   }
   if (mask & GL_LIGHTING_BIT) {
      MEMCPY( &dst->Light, &src->Light, sizeof(struct gl_light_attrib) );
      /*       gl_reinit_light_attrib( &dst->Light ); */
   }
   if (mask & GL_LINE_BIT) {
      MEMCPY( &dst->Line, &src->Line, sizeof(struct gl_line_attrib) );
   }
   if (mask & GL_LIST_BIT) {
      MEMCPY( &dst->List, &src->List, sizeof(struct gl_list_attrib) );
   }
   if (mask & GL_PIXEL_MODE_BIT) {
      MEMCPY( &dst->Pixel, &src->Pixel, sizeof(struct gl_pixel_attrib) );
   }
   if (mask & GL_POINT_BIT) {
      MEMCPY( &dst->Point, &src->Point, sizeof(struct gl_point_attrib) );
   }
   if (mask & GL_POLYGON_BIT) {
      MEMCPY( &dst->Polygon, &src->Polygon, sizeof(struct gl_polygon_attrib) );
   }
   if (mask & GL_POLYGON_STIPPLE_BIT) {
      /* Use loop instead of MEMCPY due to problem with Portland Group's
       * C compiler.  Reported by John Stone.
       */
      int i;
      for (i=0;i<32;i++) {
         dst->PolygonStipple[i] = src->PolygonStipple[i];
      }
   }
   if (mask & GL_SCISSOR_BIT) {
      MEMCPY( &dst->Scissor, &src->Scissor, sizeof(struct gl_scissor_attrib) );
   }
   if (mask & GL_STENCIL_BUFFER_BIT) {
      MEMCPY( &dst->Stencil, &src->Stencil, sizeof(struct gl_stencil_attrib) );
   }
   if (mask & GL_TEXTURE_BIT) {
      MEMCPY( &dst->Texture, &src->Texture, sizeof(struct gl_texture_attrib) );
   }
   if (mask & GL_TRANSFORM_BIT) {
      MEMCPY( &dst->Transform, &src->Transform, sizeof(struct gl_transform_attrib) );
   }
   if (mask & GL_VIEWPORT_BIT) {
      MEMCPY( &dst->Viewport, &src->Viewport, sizeof(struct gl_viewport_attrib) );
   }
}


/*
 * Set the current context, binding the given frame buffer to the context.
 */
void gl_make_current( GLcontext *newCtx, GLframebuffer *buffer )
{
   gl_make_current2( newCtx, buffer, buffer );
}


/*
 * Bind the given context to the given draw-buffer and read-buffer
 * and make it the current context for this thread.
 */
void gl_make_current2( GLcontext *newCtx, GLframebuffer *drawBuffer,
                       GLframebuffer *readBuffer )
{
#if 0
   GLcontext *oldCtx = gl_get_context();

   /* Flush the old context
    */
   if (oldCtx) {
      ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(oldCtx, "gl_make_current");

      /* unbind frame buffers from context */
      if (oldCtx->DrawBuffer) {
         oldCtx->DrawBuffer = NULL;
      }
      if (oldCtx->ReadBuffer) {
         oldCtx->ReadBuffer = NULL;
      }
   }
#endif

   /* We call this function periodically (just here for now) in
    * order to detect when multithreading has begun.
    */
   _glapi_check_multithread();

   _glapi_set_context((void *) newCtx);
   ASSERT(gl_get_current_context() == newCtx);
   if (newCtx) {
      SET_IMMEDIATE(newCtx, newCtx->input);
      _glapi_set_dispatch(newCtx->CurrentDispatch);
   }
   else {
      _glapi_set_dispatch(NULL);  /* none current */
   }

   if (MESA_VERBOSE) fprintf(stderr, "gl_make_current()\n");

   if (newCtx && drawBuffer && readBuffer) {
      /* TODO: check if newCtx and buffer's visual match??? */
      newCtx->DrawBuffer = drawBuffer;
      newCtx->ReadBuffer = readBuffer;
      newCtx->NewState = NEW_ALL;   /* just to be safe */
      gl_update_state( newCtx );
   }

   /* We can use this to help debug user's problems.  Tell the to set
    * the MESA_INFO env variable before running their app.  Then the
    * first time each context is made current we'll print some useful
    * information.
    */
   if (newCtx && newCtx->FirstTimeCurrent) {
      if (getenv("MESA_INFO")) {
         fprintf(stderr, "Mesa GL_VERSION = %s\n", (char *) _mesa_GetString(GL_VERSION));
         fprintf(stderr, "Mesa GL_RENDERER = %s\n", (char *) _mesa_GetString(GL_RENDERER));
         fprintf(stderr, "Mesa GL_VENDOR = %s\n", (char *) _mesa_GetString(GL_VENDOR));
         fprintf(stderr, "Mesa GL_EXTENSIONS = %s\n", (char *) _mesa_GetString(GL_EXTENSIONS));
#if defined(THREADS)
         fprintf(stderr, "Mesa thread-safe: YES\n");
#else
         fprintf(stderr, "Mesa thread-safe: NO\n");
#endif
#if defined(USE_X86_ASM)
         fprintf(stderr, "Mesa x86-optimized: YES\n");
#else
         fprintf(stderr, "Mesa x86-optimized: NO\n");
#endif
      }
      newCtx->FirstTimeCurrent = GL_FALSE;
   }
}



/*
 * Return current context handle for the calling thread.
 * This isn't the fastest way to get the current context.
 * If you need speed, see the GET_CURRENT_CONTEXT() macro in context.h
 */
GLcontext *gl_get_current_context( void )
{
   return (GLcontext *) _glapi_get_context();
}



/*
 * This should be called by device drivers just before they do a
 * swapbuffers.  Any pending rendering commands will be executed.
 */
void
_mesa_swapbuffers(GLcontext *ctx)
{
   FLUSH_VB( ctx, "swap buffers" );
}



/*
 * Return pointer to this context's current API dispatch table.
 * It'll either be the immediate-mode execute dispatcher or the
 * display list compile dispatcher.
 */
struct _glapi_table *
_mesa_get_dispatch(GLcontext *ctx)
{
   return ctx->CurrentDispatch;
}



/**********************************************************************/
/*****                Miscellaneous functions                     *****/
/**********************************************************************/


/*
 * This function is called when the Mesa user has stumbled into a code
 * path which may not be implemented fully or correctly.
 */
void gl_problem( const GLcontext *ctx, const char *s )
{
   fprintf( stderr, "Mesa implementation error: %s\n", s );
   fprintf( stderr, "Report to mesa-bugs@mesa3d.org\n" );
   (void) ctx;
}



/*
 * This is called to inform the user that he or she has tried to do
 * something illogical or if there's likely a bug in their program
 * (like enabled depth testing without a depth buffer).
 */
void gl_warning( const GLcontext *ctx, const char *s )
{
   GLboolean debug;
#ifdef DEBUG
   debug = GL_TRUE;
#else
   if (getenv("MESA_DEBUG")) {
      debug = GL_TRUE;
   }
   else {
      debug = GL_FALSE;
   }
#endif
   if (debug) {
      fprintf( stderr, "Mesa warning: %s\n", s );
   }
   (void) ctx;
}



/*
 * Compile an error into current display list.
 */
void gl_compile_error( GLcontext *ctx, GLenum error, const char *s )
{
   if (ctx->CompileFlag)
      gl_save_error( ctx, error, s );

   if (ctx->ExecuteFlag)
      gl_error( ctx, error, s );
}



/*
 * This is Mesa's error handler.  Normally, all that's done is the updating
 * of the current error value.  If Mesa is compiled with -DDEBUG or if the
 * environment variable "MESA_DEBUG" is defined then a real error message
 * is printed to stderr.
 * Input:  error - the error value
 *         s - a diagnostic string
 */
void gl_error( GLcontext *ctx, GLenum error, const char *s )
{
   GLboolean debug;

#ifdef DEBUG
   debug = GL_TRUE;
#else
   if (getenv("MESA_DEBUG")) {
      debug = GL_TRUE;
   }
   else {
      debug = GL_FALSE;
   }
#endif

   if (debug) {
      char errstr[1000];

      switch (error) {
	 case GL_NO_ERROR:
	    strcpy( errstr, "GL_NO_ERROR" );
	    break;
	 case GL_INVALID_VALUE:
	    strcpy( errstr, "GL_INVALID_VALUE" );
	    break;
	 case GL_INVALID_ENUM:
	    strcpy( errstr, "GL_INVALID_ENUM" );
	    break;
	 case GL_INVALID_OPERATION:
	    strcpy( errstr, "GL_INVALID_OPERATION" );
	    break;
	 case GL_STACK_OVERFLOW:
	    strcpy( errstr, "GL_STACK_OVERFLOW" );
	    break;
	 case GL_STACK_UNDERFLOW:
	    strcpy( errstr, "GL_STACK_UNDERFLOW" );
	    break;
	 case GL_OUT_OF_MEMORY:
	    strcpy( errstr, "GL_OUT_OF_MEMORY" );
	    break;
	 default:
	    strcpy( errstr, "unknown" );
	    break;
      }
      fprintf( stderr, "Mesa user error: %s in %s\n", errstr, s );
   }

   if (ctx->ErrorValue==GL_NO_ERROR) {
      ctx->ErrorValue = error;
   }

   /* Call device driver's error handler, if any.  This is used on the Mac. */
   if (ctx->Driver.Error) {
      (*ctx->Driver.Error)( ctx );
   }
}



void
_mesa_Finish( void )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glFinish");
   if (ctx->Driver.Finish) {
      (*ctx->Driver.Finish)( ctx );
   }
}



void
_mesa_Flush( void )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glFlush");
   if (ctx->Driver.Flush) {
      (*ctx->Driver.Flush)( ctx );
   }
}