/*************************************************************************
 *                                                                       *
 * 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.                     *
 *                                                                       *
 *************************************************************************/

/*

standard ODE geometry primitives: public API and pairwise collision functions.

the rule is that only the low level primitive collision functions should set
dContactGeom::g1 and dContactGeom::g2.

*/

#include <ode/common.h>
#include <ode/collision.h>
#include <ode/matrix.h>
#include <ode/rotation.h>
#include <ode/odemath.h>
#include "collision_kernel.h"
#include "collision_std.h"
#include "collision_util.h"



//****************************************************************************
// sphere public API

dxSphere::dxSphere (dSpaceID space, dReal _radius) : dxGeom (space,1)
{
  type = dSphereClass;
  radius = _radius;
}


void dxSphere::computeAABB()
{
  aabb[0] = final_posr->pos[0] - radius;
  aabb[1] = final_posr->pos[0] + radius;
  aabb[2] = final_posr->pos[1] - radius;
  aabb[3] = final_posr->pos[1] + radius;
  aabb[4] = final_posr->pos[2] - radius;
  aabb[5] = final_posr->pos[2] + radius;
}


EXPORT_C dGeomID dCreateSphere (dSpaceID space, dReal radius)
{
  return new dxSphere (space,radius);
}


EXPORT_C void dGeomSphereSetRadius (dGeomID g, dReal radius)
{
  dxSphere *s = (dxSphere*) g;
  s->radius = radius;
  dGeomMoved (g);
}


EXPORT_C dReal dGeomSphereGetRadius (dGeomID g)
{
  dxSphere *s = (dxSphere*) g;
  return s->radius;
}


EXPORT_C dReal dGeomSpherePointDepth (dGeomID g, dReal x, dReal y, dReal z)
{
  g->recomputePosr();
  
  dxSphere *s = (dxSphere*) g;
  dReal * pos = s->final_posr->pos;
  return s->radius - dSqrt (dMUL((x-pos[0]),(x-pos[0])) +
			    dMUL((y-pos[1]),(y-pos[1])) +
			    dMUL((z-pos[2]),(z-pos[2])));
}

//****************************************************************************
// pairwise collision functions for standard geom types

int dCollideSphereSphere (dxGeom *o1, dxGeom *o2, int /*flags*/,
			  dContactGeom *contact, int /*skip*/)
{
  dxSphere *sphere1 = (dxSphere*) o1;
  dxSphere *sphere2 = (dxSphere*) o2;

  contact->g1 = o1;
  contact->g2 = o2;

  return dCollideSpheres (o1->final_posr->pos,sphere1->radius,
			  o2->final_posr->pos,sphere2->radius,contact);
}


int dCollideSphereBox (dxGeom *o1, dxGeom *o2, int /*flags*/,
		       dContactGeom *contact, int /*skip*/)
{
  // this is easy. get the sphere center `p' relative to the box, and then clip
  // that to the boundary of the box (call that point `q'). if q is on the
  // boundary of the box and |p-q| is <= sphere radius, they touch.
  // if q is inside the box, the sphere is inside the box, so set a contact
  // normal to push the sphere to the closest box face.

  dVector3 l,t,p,q,r;
  dReal depth;
  int onborder = 0;

  dxSphere *sphere = (dxSphere*) o1;
  dxBox *box = (dxBox*) o2;

  contact->g1 = o1;
  contact->g2 = o2;

  p[0] = o1->final_posr->pos[0] - o2->final_posr->pos[0];
  p[1] = o1->final_posr->pos[1] - o2->final_posr->pos[1];
  p[2] = o1->final_posr->pos[2] - o2->final_posr->pos[2];

  l[0] = dMUL(box->side[0],REAL(0.5));
  t[0] = dDOT14(p,o2->final_posr->R);
  if (t[0] < -l[0]) { t[0] = -l[0]; onborder = 1; }
  if (t[0] >  l[0]) { t[0] =  l[0]; onborder = 1; }

  l[1] = dMUL(box->side[1],REAL(0.5));
  t[1] = dDOT14(p,o2->final_posr->R+1);
  if (t[1] < -l[1]) { t[1] = -l[1]; onborder = 1; }
  if (t[1] >  l[1]) { t[1] =  l[1]; onborder = 1; }

  t[2] = dDOT14(p,o2->final_posr->R+2);
  l[2] = dMUL(box->side[2],REAL(0.5));
  if (t[2] < -l[2]) { t[2] = -l[2]; onborder = 1; }
  if (t[2] >  l[2]) { t[2] =  l[2]; onborder = 1; }

  if (!onborder) {
    // sphere center inside box. find closest face to `t'
    dReal min_distance = l[0] - dFabs(t[0]);
    int mini = 0;
    for (int i=1; i<3; i++) {
      dReal face_distance = l[i] - dFabs(t[i]);
      if (face_distance < min_distance) {
	min_distance = face_distance;
	mini = i;
      }
    }
    // contact position = sphere center
    contact->pos[0] = o1->final_posr->pos[0];
    contact->pos[1] = o1->final_posr->pos[1];
    contact->pos[2] = o1->final_posr->pos[2];
    // contact normal points to closest face
    dVector3 tmp;
    tmp[0] = 0;
    tmp[1] = 0;
    tmp[2] = 0;
    tmp[mini] = (t[mini] > 0) ? REAL(1.0) : REAL(-1.0);
    dMULTIPLY0_331 (contact->normal,o2->final_posr->R,tmp);
    // contact depth = distance to wall along normal plus radius
    contact->depth = min_distance + sphere->radius;
    return 1;
  }

  t[3] = 0;			//@@@ hmmm
  dMULTIPLY0_331 (q,o2->final_posr->R,t);
  r[0] = p[0] - q[0];
  r[1] = p[1] - q[1];
  r[2] = p[2] - q[2];
  depth = sphere->radius - dSqrt(dDOT(r,r));
  if (depth < 0) return 0;
  contact->pos[0] = q[0] + o2->final_posr->pos[0];
  contact->pos[1] = q[1] + o2->final_posr->pos[1];
  contact->pos[2] = q[2] + o2->final_posr->pos[2];
  contact->normal[0] = r[0];
  contact->normal[1] = r[1];
  contact->normal[2] = r[2];
  dNormalize3 (contact->normal);
  contact->depth = depth;
  return 1;
}


int dCollideSpherePlane (dxGeom *o1, dxGeom *o2, int /*flags*/,
			 dContactGeom *contact, int /*skip*/)
{
  dxSphere *sphere = (dxSphere*) o1;
  dxPlane *plane = (dxPlane*) o2;

  contact->g1 = o1;
  contact->g2 = o2;
  dReal k = dDOT (o1->final_posr->pos,plane->p);
  dReal depth = plane->p[3] - k + sphere->radius;
  if (depth >= 0) {
    contact->normal[0] = plane->p[0];
    contact->normal[1] = plane->p[1];
    contact->normal[2] = plane->p[2];
    contact->pos[0] = o1->final_posr->pos[0] - dMUL(plane->p[0],sphere->radius);
    contact->pos[1] = o1->final_posr->pos[1] - dMUL(plane->p[1],sphere->radius);
    contact->pos[2] = o1->final_posr->pos[2] - dMUL(plane->p[2],sphere->radius);
    contact->depth = depth;
    return 1;
  }
  else return 0;
}