tess.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

  case GLU_TESS_ERROR_DATA:
    tess->callErrorData = (fn == NULL) ?
	&__gl_noErrorData : (void (GLAPIENTRY *)(GLenum, void *)) fn;
    return;
  case GLU_TESS_COMBINE:
    tess->callCombine = (fn == NULL) ? &noCombine :
	(void (GLAPIENTRY *)(GLdouble [3],void *[4], GLfloat [4], void ** )) fn;
    return;
  case GLU_TESS_COMBINE_DATA:
    tess->callCombineData = (fn == NULL) ? &__gl_noCombineData :
					   (void (GLAPIENTRY *)(GLdouble [3],
						     void *[4],
						     GLfloat [4],
						     void **,
						     void *)) fn;
    return;
  case GLU_TESS_MESH:
    tess->callMesh = (fn == NULL) ? &noMesh : (void (GLAPIENTRY *)(GLUmesh *)) fn;
    return;
  default:
    CALL_ERROR_OR_ERROR_DATA( GLU_INVALID_ENUM );
    return;
  }
}

static int AddVertex( GLUtesselator *tess, GLdouble coords[3], void *data )
{
  GLUhalfEdge *e;

  e = tess->lastEdge;
  if( e == NULL ) {
    /* Make a self-loop (one vertex, one edge). */

    e = __gl_meshMakeEdge( tess->mesh );
    if (e == NULL) return 0;
    if ( !__gl_meshSplice( e, e->Sym ) ) return 0;
  } else {
    /* Create a new vertex and edge which immediately follow e
     * in the ordering around the left face.
     */
    if (__gl_meshSplitEdge( e ) == NULL) return 0;
    e = e->Lnext;
  }

  /* The new vertex is now e->Org. */
  e->Org->data = data;
  e->Org->coords[0] = coords[0];
  e->Org->coords[1] = coords[1];
  e->Org->coords[2] = coords[2];

  /* The winding of an edge says how the winding number changes as we
   * cross from the edge''s right face to its left face.  We add the
   * vertices in such an order that a CCW contour will add +1 to
   * the winding number of the region inside the contour.
   */
  e->winding = 1;
  e->Sym->winding = -1;

  tess->lastEdge = e;

  return 1;
}


static void CacheVertex( GLUtesselator *tess, GLdouble coords[3], void *data )
{
  CachedVertex *v = &tess->cache[tess->cacheCount];

  v->data = data;
  v->coords[0] = coords[0];
  v->coords[1] = coords[1];
  v->coords[2] = coords[2];
  ++tess->cacheCount;
}


static int EmptyCache( GLUtesselator *tess )
{
  CachedVertex *v = tess->cache;
  CachedVertex *vLast;

  tess->mesh = __gl_meshNewMesh();
  if (tess->mesh == NULL) return 0;

  for( vLast = v + tess->cacheCount; v < vLast; ++v ) {
    if ( !AddVertex( tess, v->coords, v->data ) ) return 0;
  }
  tess->cacheCount = 0;
  tess->emptyCache = FALSE;

  return 1;
}


void GLAPIENTRY
gluTessVertex( GLUtesselator *tess, GLdouble coords[3], void *data )
{
  int i, tooLarge = FALSE;
  GLdouble x, clamped[3];

  RequireState( tess, T_IN_CONTOUR );

  if( tess->emptyCache ) {
    if ( !EmptyCache( tess ) ) {
       CALL_ERROR_OR_ERROR_DATA( GLU_OUT_OF_MEMORY );
       return;
    }
    tess->lastEdge = NULL;
  }
  for( i = 0; i < 3; ++i ) {
    x = coords[i];
    if( x < - GLU_TESS_MAX_COORD ) {
      x = - GLU_TESS_MAX_COORD;
      tooLarge = TRUE;
    }
    if( x > GLU_TESS_MAX_COORD ) {
      x = GLU_TESS_MAX_COORD;
      tooLarge = TRUE;
    }
    clamped[i] = x;
  }
  if( tooLarge ) {
    CALL_ERROR_OR_ERROR_DATA( GLU_TESS_COORD_TOO_LARGE );
  }

  if( tess->mesh == NULL ) {
    if( tess->cacheCount < TESS_MAX_CACHE ) {
      CacheVertex( tess, clamped, data );
      return;
    }
    if ( !EmptyCache( tess ) ) {
       CALL_ERROR_OR_ERROR_DATA( GLU_OUT_OF_MEMORY );
       return;
    }
  }
  if ( !AddVertex( tess, clamped, data ) ) {
       CALL_ERROR_OR_ERROR_DATA( GLU_OUT_OF_MEMORY );
  }
}


void GLAPIENTRY
gluTessBeginPolygon( GLUtesselator *tess, void *data )
{
  RequireState( tess, T_DORMANT );

  tess->state = T_IN_POLYGON;
  tess->cacheCount = 0;
  tess->emptyCache = FALSE;
  tess->mesh = NULL;

  tess->polygonData= data;
}


void GLAPIENTRY
gluTessBeginContour( GLUtesselator *tess )
{
  RequireState( tess, T_IN_POLYGON );

  tess->state = T_IN_CONTOUR;
  tess->lastEdge = NULL;
  if( tess->cacheCount > 0 ) {
    /* Just set a flag so we don't get confused by empty contours
     * -- these can be generated accidentally with the obsolete
     * NextContour() interface.
     */
    tess->emptyCache = TRUE;
  }
}


void GLAPIENTRY
gluTessEndContour( GLUtesselator *tess )
{
  RequireState( tess, T_IN_CONTOUR );
  tess->state = T_IN_POLYGON;
}

void GLAPIENTRY
gluTessEndPolygon( GLUtesselator *tess )
{
  GLUmesh *mesh;

  if (setjmp(tess->env) != 0) { 
     /* come back here if out of memory */
     CALL_ERROR_OR_ERROR_DATA( GLU_OUT_OF_MEMORY );
     return;
  }

  RequireState( tess, T_IN_POLYGON );
  tess->state = T_DORMANT;

  if( tess->mesh == NULL ) {
    if( ! tess->flagBoundary && tess->callMesh == &noMesh ) {

      /* Try some special code to make the easy cases go quickly
       * (eg. convex polygons).  This code does NOT handle multiple contours,
       * intersections, edge flags, and of course it does not generate
       * an explicit mesh either.
       */
      if( __gl_renderCache( tess )) {
	tess->polygonData= NULL;
	return;
      }
    }
    if ( !EmptyCache( tess ) ) longjmp(tess->env,1); /* could've used a label*/
  }

  /* Determine the polygon normal and project vertices onto the plane
   * of the polygon.
   */
  __gl_projectPolygon( tess );

  /* __gl_computeInterior( tess ) computes the planar arrangement specified
   * by the given contours, and further subdivides this arrangement
   * into regions.  Each region is marked "inside" if it belongs
   * to the polygon, according to the rule given by tess->windingRule.
   * Each interior region is guaranteed be monotone.
   */
  if ( !__gl_computeInterior( tess ) ) {
     longjmp(tess->env,1);	/* could've used a label */
  }

  mesh = tess->mesh;
  if( ! tess->fatalError ) {
    int rc = 1;

    /* If the user wants only the boundary contours, we throw away all edges
     * except those which separate the interior from the exterior.
     * Otherwise we tessellate all the regions marked "inside".
     */
    if( tess->boundaryOnly ) {
      rc = __gl_meshSetWindingNumber( mesh, 1, TRUE );
    } else {
      rc = __gl_meshTessellateInterior( mesh );
    }
    if (rc == 0) longjmp(tess->env,1);	/* could've used a label */

    __gl_meshCheckMesh( mesh );

    if( tess->callBegin != &noBegin || tess->callEnd != &noEnd
       || tess->callVertex != &noVertex || tess->callEdgeFlag != &noEdgeFlag
       || tess->callBeginData != &__gl_noBeginData
       || tess->callEndData != &__gl_noEndData
       || tess->callVertexData != &__gl_noVertexData
       || tess->callEdgeFlagData != &__gl_noEdgeFlagData )
    {
      if( tess->boundaryOnly ) {
	__gl_renderBoundary( tess, mesh );  /* output boundary contours */
      } else {
	__gl_renderMesh( tess, mesh );	   /* output strips and fans */
      }
    }
    if( tess->callMesh != &noMesh ) {

      /* Throw away the exterior faces, so that all faces are interior.
       * This way the user doesn't have to check the "inside" flag,
       * and we don't need to even reveal its existence.  It also leaves
       * the freedom for an implementation to not generate the exterior
       * faces in the first place.
       */
      __gl_meshDiscardExterior( mesh );
      (*tess->callMesh)( mesh );		/* user wants the mesh itself */
      tess->mesh = NULL;
      tess->polygonData= NULL;
      return;
    }
  }
  __gl_meshDeleteMesh( mesh );
  tess->polygonData= NULL;
  tess->mesh = NULL;
}


/*XXXblythe unused function*/
#if 0
void GLAPIENTRY
gluDeleteMesh( GLUmesh *mesh )
{
  __gl_meshDeleteMesh( mesh );
}
#endif



/*******************************************************/

/* Obsolete calls -- for backward compatibility */

void GLAPIENTRY
gluBeginPolygon( GLUtesselator *tess )
{
  gluTessBeginPolygon( tess, NULL );
  gluTessBeginContour( tess );
}


/*ARGSUSED*/
void GLAPIENTRY
gluNextContour( GLUtesselator *tess, GLenum type )
{
  gluTessEndContour( tess );
  gluTessBeginContour( tess );
}


void GLAPIENTRY
gluEndPolygon( GLUtesselator *tess )
{
  gluTessEndContour( tess );
  gluTessEndPolygon( tess );
}