/*************************************************************************
 *                                                                       *
 * Open Dynamics Engine, Copyright (C) 2001-2003 Russell L. Smith.       *
 * All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *
 *                                                                       *
 * This library is free software; you can redistribute it and/or         *
 * modify it under the terms of EITHER:                                  *
 *   (1) 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. The text of the GNU Lesser      *
 *       General Public License is included with this library in the     *
 *       file LICENSE.TXT.                                               *
 *   (2) The BSD-style license that is included with this library in     *
 *       the file LICENSE-BSD.TXT.                                       *
 *                                                                       *
 * 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 files    *
 * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
 *                                                                       *
 *************************************************************************/

/*

internal data structures and functions for collision detection.

*/

#ifndef _ODE_COLLISION_KERNEL_H_
#define _ODE_COLLISION_KERNEL_H_

#include <ode/common.h>
#include <ode/contact.h>
#include <ode/collision.h>
#include "objects.h"

//****************************************************************************
// constants and macros

// mask for the number-of-contacts field in the dCollide() flags parameter
#define NUMC_MASK (0xffff)

#define IS_SPACE(geom) \
  ((geom)->type >= dFirstSpaceClass && (geom)->type <= dLastSpaceClass)

//****************************************************************************
// geometry object base class


// geom flags.
//
// GEOM_DIRTY means that the space data structures for this geom are
// potentially not up to date. NOTE THAT all space parents of a dirty geom
// are themselves dirty. this is an invariant that must be enforced.
//
// GEOM_AABB_BAD means that the cached AABB for this geom is not up to date.
// note that GEOM_DIRTY does not imply GEOM_AABB_BAD, as the geom might
// recalculate its own AABB but does not know how to update the space data
// structures for the space it is in. but GEOM_AABB_BAD implies GEOM_DIRTY.
// the valid combinations are: 
//		0
//		GEOM_DIRTY
//		GEOM_DIRTY|GEOM_AABB_BAD
//		GEOM_DIRTY|GEOM_AABB_BAD|GEOM_POSR_BAD

enum {
  GEOM_DIRTY	= 1,	// geom is 'dirty', i.e. position unknown
  GEOM_POSR_BAD = 2,	// geom's final posr is not valid
  GEOM_AABB_BAD	= 4,	// geom's AABB is not valid
  GEOM_PLACEABLE = 8,	// geom is placeable
  GEOM_ENABLED = 16,		// geom is enabled

  // Ray specific
  RAY_FIRSTCONTACT = 0x10000,
  RAY_BACKFACECULL = 0x20000,
  RAY_CLOSEST_HIT  = 0x40000
};


// geometry object base class. pos and R will either point to a separately
// allocated buffer (if body is 0 - pos points to the dxPosR object) or to
// the pos and R of the body (if body nonzero).
// a dGeomID is a pointer to this object.

struct dxGeom : public dBase {
  int type;		// geom type number, set by subclass constructor
  int gflags;		// flags used by geom and space
  void *data;		// user-defined data pointer
  dBodyID body;		// dynamics body associated with this object (if any)
  dxGeom *body_next;	// next geom in body's linked list of associated geoms
  dxPosR *final_posr;	// final position of the geom in world coordinates
  dxPosR *offset_posr;	// offset from body in local coordinates

  // information used by spaces
  dxGeom *next;		// next geom in linked list of geoms
  dxGeom **tome;	// linked list backpointer
  dxSpace *parent_space;// the space this geom is contained in, 0 if none
  dReal aabb[6];	// cached AABB for this space
  unsigned long category_bits,collide_bits;

  dxGeom (dSpaceID _space, int is_placeable);
  virtual ~dxGeom();


  // calculate our new final position from our offset and body
  void computePosr();

  // recalculate our new final position if needed
  void recomputePosr()
  {
    if (gflags & GEOM_POSR_BAD) {
      computePosr();
      gflags &= ~GEOM_POSR_BAD;
    }
  }

  virtual void computeAABB()=0;
  // compute the AABB for this object and put it in aabb. this function
  // always performs a fresh computation, it does not inspect the
  // GEOM_AABB_BAD flag.

  virtual int AABBTest (dxGeom *o, dReal aabb[6]);
  // test whether the given AABB object intersects with this object, return
  // 1=yes, 0=no. this is used as an early-exit test in the space collision
  // functions. the default implementation returns 1, which is the correct
  // behavior if no more detailed implementation can be provided.

  // utility functions

  // compute the AABB only if it is not current. this function manipulates
  // the GEOM_AABB_BAD flag.

  void recomputeAABB() {
    if (gflags & GEOM_AABB_BAD) {
      // our aabb functions assume final_posr is up to date
      recomputePosr(); 
      computeAABB();
      gflags &= ~GEOM_AABB_BAD;
    }
  }

  // add and remove this geom from a linked list maintained by a space.

  void spaceAdd (dxGeom **first_ptr) {
    next = *first_ptr;
    tome = first_ptr;
    if (*first_ptr) (*first_ptr)->tome = &next;
    *first_ptr = this;
  }
  void spaceRemove() {
    if (next) next->tome = tome;
    *tome = next;
  }

  // add and remove this geom from a linked list maintained by a body.

  void bodyAdd (dxBody *b) {
    body = b;
    body_next = b->geom;
    b->geom = this;
  }
  void bodyRemove();
};

//****************************************************************************
// the base space class
//
// the contained geoms are divided into two kinds: clean and dirty.
// the clean geoms have not moved since they were put in the list,
// and their AABBs are valid. the dirty geoms have changed position, and
// their AABBs are may not be valid. the two types are distinguished by the
// GEOM_DIRTY flag. all dirty geoms come *before* all clean geoms in the list.

struct dxSpace : public dxGeom {
  int count;			// number of geoms in this space
  dxGeom *first;		// first geom in list
  int cleanup;			// cleanup mode, 1=destroy geoms on exit

  // cached state for getGeom()
  int current_index;		// only valid if current_geom != 0
  dxGeom *current_geom;		// if 0 then there is no information

  // locking stuff. the space is locked when it is currently traversing its
  // internal data structures, e.g. in collide() and collide2(). operations
  // that modify the contents of the space are not permitted when the space
  // is locked.
  int lock_count;

  dxSpace (dSpaceID _space);
  ~dxSpace();

  void computeAABB();

  void setCleanup (int mode);
  int getCleanup();
  int query (dxGeom *geom);
  int getNumGeoms();
  virtual dxGeom *getGeom (int i);

  virtual void add (dxGeom *);
  virtual void remove (dxGeom *);
  virtual void dirty (dxGeom *);

  virtual void cleanGeoms()=0;
  // turn all dirty geoms into clean geoms by computing their AABBs and any
  // other space data structures that are required. this should clear the
  // GEOM_DIRTY and GEOM_AABB_BAD flags of all geoms.

  virtual void collide (void *data, dNearCallback *callback)=0;
  virtual void collide2 (void *data, dxGeom *geom, dNearCallback *callback)=0;
};


#endif