src/glu/sgi/libnurbs/internals/curvesub.cc

   1 /*
   2 ** License Applicability. Except to the extent portions of this file are
   3 ** made subject to an alternative license as permitted in the SGI Free
   4 ** Software License B, Version 1.1 (the "License"), the contents of this
   5 ** file are subject only to the provisions of the License. You may not use
   6 ** this file except in compliance with the License. You may obtain a copy
   7 ** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
   8 ** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
   9 **
  10 ** http://oss.sgi.com/projects/FreeB
  11 **
  12 ** Note that, as provided in the License, the Software is distributed on an
  13 ** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
  14 ** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
  15 ** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
  16 ** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
  17 **
  18 ** Original Code. The Original Code is: OpenGL Sample Implementation,
  19 ** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
  20 ** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
  21 ** Copyright in any portions created by third parties is as indicated
  22 ** elsewhere herein. All Rights Reserved.
  23 **
  24 ** Additional Notice Provisions: The application programming interfaces
  25 ** established by SGI in conjunction with the Original Code are The
  26 ** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
  27 ** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
  28 ** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
  29 ** Window System(R) (Version 1.3), released October 19, 1998. This software
  30 ** was created using the OpenGL(R) version 1.2.1 Sample Implementation
  31 ** published by SGI, but has not been independently verified as being
  32 ** compliant with the OpenGL(R) version 1.2.1 Specification.
  33 */
  34
  35 /*
  36  * curvesub.c++
  37  *
  38  */
  39
  40 #include "glimports.h"
  41 #include "myassert.h"
  42 #include "mystdio.h"
  43 #include "subdivider.h"
  44 #include "renderhints.h"
  45 #include "backend.h"
  46 #include "quilt.h"
  47 #include "curvelist.h"
  48 #include "nurbsconsts.h"
  49
  50 /*--------------------------------------------------------------------------
  51  * drawCurves - main curve rendering entry point
  52  *--------------------------------------------------------------------------
  53  */
  54
  55 void
  56 Subdivider::drawCurves( void )
  57 {
  58     REAL        from[1], to[1];
  59     Flist       bpts;
  60     qlist->getRange( from, to, bpts );
  61
  62     renderhints.init( );
  63
  64     backend.bgncurv();
  65     for( int i=bpts.start; i<bpts.end-1; i++ ) {
  66         REAL pta, ptb;
  67         pta = bpts.pts[i];
  68         ptb = bpts.pts[i+1];
  69
  70         qlist->downloadAll( &pta, &ptb, backend );
  71
  72         Curvelist curvelist( qlist, pta, ptb );
  73         samplingSplit( curvelist, renderhints.maxsubdivisions );
  74     }
  75     backend.endcurv();
  76 }
  77
  78
  79 /*--------------------------------------------------------------------------
  80  * samplingSplit - recursively subdivide patch, cull check each subpatch
  81  *--------------------------------------------------------------------------
  82  */
  83
  84 void
  85 Subdivider::samplingSplit( Curvelist& curvelist, int subdivisions )
  86 {
  87     if( curvelist.cullCheck() == CULL_TRIVIAL_REJECT )  return;
  88
  89     curvelist.getstepsize();
  90
  91     if( curvelist.needsSamplingSubdivision() && (subdivisions > 0) ) {
  92         REAL mid = ( curvelist.range[0] + curvelist.range[1] ) * 0.5;
  93         Curvelist lowerlist( curvelist, mid );
  94         samplingSplit( lowerlist, subdivisions-1 ); // lower
  95         samplingSplit( curvelist, subdivisions-1 ); // upper
  96     } else {
  97         long nu = 1 + ((long) (curvelist.range[2] / curvelist.stepsize));
  98         backend.curvgrid( curvelist.range[0], curvelist.range[1], nu );
  99         backend.curvmesh( 0, nu );
 100     }
 101 }
 102