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/*
*
* Copyright (C) 2000 Silicon Graphics, Inc. All Rights Reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* Further, this software is distributed without any warranty that it is
* free of the rightful claim of any third person regarding infringement
* or the like. Any license provided herein, whether implied or
* otherwise, applies only to this software file. Patent licenses, if
* any, provided herein do not apply to combinations of this program with
* other software, or any other product whatsoever.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
* Mountain View, CA 94043, or:
*
* http://www.sgi.com
*
* For further information regarding this notice, see:
*
* http://oss.sgi.com/projects/GenInfo/NoticeExplan/
*
*/
// -*- C++ -*-
/*
* Copyright (C) 1990,91 Silicon Graphics, Inc.
*
_______________________________________________________________________
______________ S I L I C O N G R A P H I C S I N C . ____________
|
| $Revision: 1.1.1.1 $
|
| Description:
| This file defines the SoLevelOfDetail node class.
|
| Author(s) : Paul S. Strauss, Nick Thompson
|
______________ S I L I C O N G R A P H I C S I N C . ____________
_______________________________________________________________________
*/
#ifndef _SO_LEVEL_OF_DETAIL_
#define _SO_LEVEL_OF_DETAIL_
#include <Inventor/fields/SoMFFloat.h>
#include <Inventor/nodes/SoGroup.h>
//////////////////////////////////////////////////////////////////////////////
//
// Class: SoLevelOfDetail
//
// Level-of-detail group node. The children of this node typically
// represent the same object or objects at varying levels of detail,
// from highest detail to lowest. The size of the objects when
// projected into the viewport is used to determine which version to
// use (i.e., which child to traverse).
//
// The size is computed as the area of the screen rectangle enclosing
// the projection of the 3D bounding box that encloses all of the
// children. When rendering, this size is compared to the values in
// the screenArea field. If the size is greater than the first value,
// child 0 is traversed. If it is smaller than the first, but greater
// than the second, child 1 is traversed, and so on. If there are
// fewer children than are required by this rule, the last child is
// traversed. The screenArea field contains just 0 by default, so the
// first child is always traversed.
//
// The size calculation takes the current complexity into account. If
// the complexity is 0 or is of type BOUNDING_BOX, the last child is
// always traversed. If the complexity is less than .5, the computed
// size is scaled down appropriately to use (possibly) a less
// detailed representation. If the complexity is greater than .5, the
// size is scaled up. At complexity 1, the first child is always used.
//
// Picking and the callback action use the same traversal rules as
// rendering. Bounding boxes are computed to enclose all children (as
// is needed to compute the projected size). All other actions are
// implemented as for SoGroup, except that SoLevelOfDetail
// saves/restores state (like a separator) when applying any action.
//
//////////////////////////////////////////////////////////////////////////////
// C-api: prefix=SoLvlOfDtl
// C-api: public=screenArea
class SoLevelOfDetail : public SoGroup {
SO_NODE_HEADER(SoLevelOfDetail);
public:
// Fields
SoMFFloat screenArea; // Areas to use for comparison
// Default constructor
SoLevelOfDetail();
// Constructor that takes approximate number of children
// C-api: name=CreateN
SoLevelOfDetail(int nChildren);
SoEXTENDER public:
// Implement actions:
virtual void doAction(SoAction *action);
virtual void callback(SoCallbackAction *action);
virtual void GLRender(SoGLRenderAction *action);
virtual void rayPick(SoRayPickAction *action);
SoINTERNAL public:
static void initClass();
protected:
virtual ~SoLevelOfDetail();
private:
// This action is used to compute the screen-space bbox
static SoGetBoundingBoxAction *bboxAction;
};
#endif /* _SO_LEVEL_OF_DETAIL_ */
|
