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

/*

core collision functions and data structures, plus part of the public API
for geometry objects

*/

#include <ode/common.h>
#include <ode/rotation.h>
#include <ode/objects.h>
#include "config.h"
#include "matrix.h"
#include "odemath.h"
#include "collision_kernel.h"
#include "collision_util.h"
#include "collision_std.h"
#include "collision_transform.h"
#include "collision_trimesh_internal.h"
#include "collision_space_internal.h"
#include "odeou.h"

#ifdef dLIBCCD_ENABLED
# include "collision_libccd.h"
#endif /* dLIBCCD_ENABLED */


#ifdef _MSC_VER
#pragma warning(disable:4291)  // for VC++, no complaints about "no matching operator delete found"
#endif

//****************************************************************************
// helper functions for dCollide()ing a space with another geom

// this struct records the parameters passed to dCollideSpaceGeom()

#if dATOMICS_ENABLED 
static volatile atomicptr s_cachedPosR = 0; // dxPosR *
#endif // dATOMICS_ENABLED

static inline dxPosR* dAllocPosr()
{
    dxPosR *retPosR;

#if dATOMICS_ENABLED
    retPosR = (dxPosR *)AtomicExchangePointer(&s_cachedPosR, NULL);

    if (!retPosR)
#endif
    {
        retPosR = (dxPosR*) dAlloc (sizeof(dxPosR));
    }

    return retPosR;
}

static inline void dFreePosr(dxPosR *oldPosR)
{
#if dATOMICS_ENABLED
    if (!AtomicCompareExchangePointer(&s_cachedPosR, NULL, (atomicptr)oldPosR))
#endif
    {
        dFree(oldPosR, sizeof(dxPosR));
    }
}

/*extern */void dClearPosrCache(void)
{
#if dATOMICS_ENABLED
    // No threads should be accessing ODE at this time already,
    // hence variable may be read directly.
    dxPosR *existingPosR = (dxPosR *)s_cachedPosR;

    if (existingPosR)
    {
        dFree(existingPosR, sizeof(dxPosR));

        s_cachedPosR = 0;
    }
#endif
}

struct SpaceGeomColliderData {
    int flags;			// space left in contacts array
    dContactGeom *contact;
    int skip;
};


static void space_geom_collider (void *data, dxGeom *o1, dxGeom *o2)
{
    SpaceGeomColliderData *d = (SpaceGeomColliderData*) data;
    if (d->flags & NUMC_MASK) {
        int n = dCollide (o1,o2,d->flags,d->contact,d->skip);
        d->contact = CONTACT (d->contact,d->skip*n);
        d->flags -= n;
    }
}


static int dCollideSpaceGeom (dxGeom *o1, dxGeom *o2, int flags, dContactGeom *contact, int skip)
{
    SpaceGeomColliderData data;
    data.flags = flags;
    data.contact = contact;
    data.skip = skip;
    dSpaceCollide2 (o1,o2,&data,&space_geom_collider);
    return (flags & NUMC_MASK) - (data.flags & NUMC_MASK);
}

//****************************************************************************
// dispatcher for the N^2 collider functions

// function pointers and modes for n^2 class collider functions

struct dColliderEntry {
    dColliderFn *fn;	// collider function, 0 = no function available
    int reverse;		// 1 = reverse o1 and o2
};
static dColliderEntry colliders[dGeomNumClasses][dGeomNumClasses];
static int colliders_initialized = 0;


// setCollider() will refuse to write over a collider entry once it has
// been written.

static void setCollider (int i, int j, dColliderFn *fn)
{
    if (colliders[i][j].fn == 0) {
        colliders[i][j].fn = fn;
        colliders[i][j].reverse = 0;
    }
    if (colliders[j][i].fn == 0) {
        colliders[j][i].fn = fn;
        colliders[j][i].reverse = 1;
    }
}


static void setAllColliders (int i, dColliderFn *fn)
{
    for (int j=0; j<dGeomNumClasses; j++) setCollider (i,j,fn);
}

/*extern */void dInitColliders()
{
    dIASSERT(!colliders_initialized);
    colliders_initialized = 1;

    memset (colliders,0,sizeof(colliders));

    int i,j;

    // setup space colliders
    for (i=dFirstSpaceClass; i <= dLastSpaceClass; i++) {
        for (j=0; j < dGeomNumClasses; j++) {
            setCollider (i,j,&dCollideSpaceGeom);
        }
    }

    setCollider (dSphereClass,dSphereClass,&dCollideSphereSphere);
    setCollider (dSphereClass,dBoxClass,&dCollideSphereBox);
    setCollider (dSphereClass,dPlaneClass,&dCollideSpherePlane);
    setCollider (dBoxClass,dBoxClass,&dCollideBoxBox);
    setCollider (dBoxClass,dPlaneClass,&dCollideBoxPlane);
    setCollider (dCapsuleClass,dSphereClass,&dCollideCapsuleSphere);
    setCollider (dCapsuleClass,dBoxClass,&dCollideCapsuleBox);
    setCollider (dCapsuleClass,dCapsuleClass,&dCollideCapsuleCapsule);
    setCollider (dCapsuleClass,dPlaneClass,&dCollideCapsulePlane);
    setCollider (dRayClass,dSphereClass,&dCollideRaySphere);
    setCollider (dRayClass,dBoxClass,&dCollideRayBox);
    setCollider (dRayClass,dCapsuleClass,&dCollideRayCapsule);
    setCollider (dRayClass,dPlaneClass,&dCollideRayPlane);
    setCollider (dRayClass,dCylinderClass,&dCollideRayCylinder);
#if dTRIMESH_ENABLED
    setCollider (dTriMeshClass,dSphereClass,&dCollideSTL);
    setCollider (dTriMeshClass,dBoxClass,&dCollideBTL);
    setCollider (dTriMeshClass,dRayClass,&dCollideRTL);
    setCollider (dTriMeshClass,dTriMeshClass,&dCollideTTL);
    setCollider (dTriMeshClass,dCapsuleClass,&dCollideCCTL);
    setCollider (dTriMeshClass,dPlaneClass,&dCollideTrimeshPlane);
    setCollider (dCylinderClass,dTriMeshClass,&dCollideCylinderTrimesh);
    setCollider (dConvexClass,dTriMeshClass,&dCollideConvexTrimesh);
#endif

#ifdef dLIBCCD_BOX_CYL
    setCollider (dBoxClass,dCylinderClass,&dCollideBoxCylinderCCD);
#else
    setCollider (dCylinderClass,dBoxClass,&dCollideCylinderBox);
#endif
    setCollider (dCylinderClass,dSphereClass,&dCollideCylinderSphere);
    setCollider (dCylinderClass,dPlaneClass,&dCollideCylinderPlane);

#ifdef dLIBCCD_CYL_CYL
    setCollider (dCylinderClass, dCylinderClass, &dCollideCylinderCylinder);
#endif
#ifdef dLIBCCD_CAP_CYL
    setCollider (dCapsuleClass, dCylinderClass, &dCollideCapsuleCylinder);
#endif

    //--> Convex Collision
#ifdef dLIBCCD_CONVEX_BOX
    setCollider (dConvexClass, dBoxClass, &dCollideConvexBoxCCD);
#else
    setCollider (dConvexClass,dBoxClass,&dCollideConvexBox);
#endif

#ifdef dLIBCCD_CONVEX_CAP
    setCollider (dConvexClass,dCapsuleClass,&dCollideConvexCapsuleCCD);
#else
    setCollider (dConvexClass,dCapsuleClass,&dCollideConvexCapsule);
#endif

#ifdef dLIBCCD_CONVEX_CYL
    setCollider (dConvexClass,dCylinderClass,&dCollideConvexCylinderCCD);
#endif

#ifdef dLIBCCD_CONVEX_SPHERE
    setCollider (dConvexClass,dSphereClass,&dCollideConvexSphereCCD);
#else
    setCollider (dSphereClass,dConvexClass,&dCollideSphereConvex);
#endif

#ifdef dLIBCCD_CONVEX_CONVEX
    setCollider (dConvexClass,dConvexClass,&dCollideConvexConvexCCD);
#else
    setCollider (dConvexClass,dConvexClass,&dCollideConvexConvex);
#endif

    setCollider (dConvexClass,dPlaneClass,&dCollideConvexPlane);
    setCollider (dRayClass,dConvexClass,&dCollideRayConvex);
    //<-- Convex Collision

    //--> dHeightfield Collision
    setCollider (dHeightfieldClass,dRayClass,&dCollideHeightfield);
    setCollider (dHeightfieldClass,dSphereClass,&dCollideHeightfield);
    setCollider (dHeightfieldClass,dBoxClass,&dCollideHeightfield);
    setCollider (dHeightfieldClass,dCapsuleClass,&dCollideHeightfield);
    setCollider (dHeightfieldClass,dCylinderClass,&dCollideHeightfield);
    setCollider (dHeightfieldClass,dConvexClass,&dCollideHeightfield);
#if dTRIMESH_ENABLED
    setCollider (dHeightfieldClass,dTriMeshClass,&dCollideHeightfield);
#endif
    //<-- dHeightfield Collision

    setAllColliders (dGeomTransformClass,&dCollideTransform);
}

/*extern */void dFinitColliders()
{
    colliders_initialized = 0;
}

void dSetColliderOverride (int i, int j, dColliderFn *fn)
{
    dIASSERT( colliders_initialized );
    dAASSERT( i < dGeomNumClasses );
    dAASSERT( j < dGeomNumClasses );

    colliders[i][j].fn = fn;
    colliders[i][j].reverse = 0;
    colliders[j][i].fn = fn;
    colliders[j][i].reverse = 1;
}

/*
*	NOTE!
*	If it is necessary to add special processing mode without contact generation
*	use NULL contact parameter value as indicator, not zero in flags.
*/
int dCollide (dxGeom *o1, dxGeom *o2, int flags, dContactGeom *contact, int skip)
{
    dAASSERT(o1 && o2 && contact);
    dUASSERT(colliders_initialized,"Please call ODE initialization (dInitODE() or similar) before using the library");
    dUASSERT(o1->type >= 0 && o1->type < dGeomNumClasses,"bad o1 class number");
    dUASSERT(o2->type >= 0 && o2->type < dGeomNumClasses,"bad o2 class number");
    // Even though comparison for greater or equal to one is used in all the 
    // other places, here it is more logical to check for greater than zero
    // because function does not require any specific number of contact slots - 
    // it must be just a positive.
    dUASSERT((flags & NUMC_MASK) > 0, "no contacts requested"); 

    // Extra precaution for zero contact count in parameters
    if ((flags & NUMC_MASK) == 0) return 0;
    // no contacts if both geoms are the same
    if (o1 == o2) return 0;

    // no contacts if both geoms on the same body, and the body is not 0
    if (o1->body == o2->body && o1->body) return 0;

    o1->recomputePosr();
    o2->recomputePosr();

    dColliderEntry *ce = &colliders[o1->type][o2->type];
    int count = 0;
    if (ce->fn) {
        if (ce->reverse) {
            count = (*ce->fn) (o2,o1,flags,contact,skip);
            for (int i=0; i<count; i++) {
                dContactGeom *c = CONTACT(contact,skip*i);
                c->normal[0] = -c->normal[0];
                c->normal[1] = -c->normal[1];
                c->normal[2] = -c->normal[2];
                dxGeom *tmp = c->g1;
                c->g1 = c->g2;
                c->g2 = tmp;
                int tmpint = c->side1;
                c->side1 = c->side2;
                c->side2 = tmpint;
            }
        }
        else {
            count = (*ce->fn) (o1,o2,flags,contact,skip);
        }
    }
    return count;
}

//****************************************************************************
// dxGeom

dxGeom::dxGeom (dSpaceID _space, int is_placeable)
{
    // setup body vars. invalid type of -1 must be changed by the constructor.
    type = -1;
    gflags = GEOM_DIRTY | GEOM_AABB_BAD | GEOM_ENABLED;
    if (is_placeable) gflags |= GEOM_PLACEABLE;
    data = 0;
    body = 0;
    body_next = 0;
    if (is_placeable) {
        final_posr = dAllocPosr();
        dSetZero (final_posr->pos,4);
        dRSetIdentity (final_posr->R);
    }
    else {
        final_posr = 0;
    }
    offset_posr = 0;

    // setup space vars
    next = 0;
    tome = 0;
    next_ex = 0;
    tome_ex = 0;
    parent_space = 0;
    dSetZero (aabb,6);
    category_bits = ~0;
    collide_bits = ~0;

    // put this geom in a space if required
    if (_space) dSpaceAdd (_space,this);
}


dxGeom::~dxGeom()
{
    if (parent_space) dSpaceRemove (parent_space,this);
    if ((gflags & GEOM_PLACEABLE) && (!body || (body && offset_posr)))
        dFreePosr(final_posr);
    if (offset_posr) dFreePosr(offset_posr);
    bodyRemove();
}

unsigned dxGeom::getParentSpaceTLSKind() const
{
    return parent_space ? parent_space->tls_kind : dSPACE_TLS_KIND_INIT_VALUE;
}

int dxGeom::AABBTest (dxGeom *, dReal [6])
{
    return 1;
}


void dxGeom::bodyRemove()
{
    if (body) {
        // delete this geom from body list
        dxGeom **last = &body->geom, *g = body->geom;
        while (g) {
            if (g == this) {
                *last = g->body_next;
                break;
            }
            last = &g->body_next;
            g = g->body_next;
        }
        body = 0;
        body_next = 0;
    }
}

inline void myswap(dReal& a, dReal& b) { dReal t=b; b=a; a=t; }


inline void matrixInvert(const dMatrix3& inMat, dMatrix3& outMat)
{
    memcpy(outMat, inMat, sizeof(dMatrix3));
    // swap _12 and _21
    myswap(outMat[0 + 4*1], outMat[1 + 4*0]);
    // swap _31 and _13
    myswap(outMat[2 + 4*0], outMat[0 + 4*2]);
    // swap _23 and _32
    myswap(outMat[1 + 4*2], outMat[2 + 4*1]);
}

void getBodyPosr(const dxPosR& offset_posr, const dxPosR& final_posr, dxPosR& body_posr)
{
    dMatrix3 inv_offset;
    matrixInvert(offset_posr.R, inv_offset);

    dMultiply0_333(body_posr.R, final_posr.R, inv_offset);
    dVector3 world_offset;
    dMultiply0_331(world_offset, body_posr.R, offset_posr.pos);
    body_posr.pos[0] = final_posr.pos[0] - world_offset[0];
    body_posr.pos[1] = final_posr.pos[1] - world_offset[1];
    body_posr.pos[2] = final_posr.pos[2] - world_offset[2];
}

void getWorldOffsetPosr(const dxPosR& body_posr, const dxPosR& world_posr, dxPosR& offset_posr)
{
    dMatrix3 inv_body;
    matrixInvert(body_posr.R, inv_body);

    dMultiply0_333(offset_posr.R, inv_body, world_posr.R);
    dVector3 world_offset;
    world_offset[0] = world_posr.pos[0] - body_posr.pos[0];
    world_offset[1] = world_posr.pos[1] - body_posr.pos[1];
    world_offset[2] = world_posr.pos[2] - body_posr.pos[2];
    dMultiply0_331(offset_posr.pos, inv_body, world_offset);
}

void dxGeom::computePosr()
{
    // should only be recalced if we need to - ie offset from a body
    dIASSERT(offset_posr);  
    dIASSERT(body);

    dMultiply0_331 (final_posr->pos,body->posr.R,offset_posr->pos);
    final_posr->pos[0] += body->posr.pos[0];
    final_posr->pos[1] += body->posr.pos[1];
    final_posr->pos[2] += body->posr.pos[2];
    dMultiply0_333 (final_posr->R,body->posr.R,offset_posr->R);
}

bool dxGeom::controlGeometry(int /*controlClass*/, int /*controlCode*/, void * /*dataValue*/, int *dataSize)
{
    dAASSERT(false && "Control class/code is not supported for current geom");

    *dataSize = 0;
    return false;
}

//****************************************************************************
// misc

dxGeom *dGeomGetBodyNext (dxGeom *geom)
{
    return geom->body_next;
}

//****************************************************************************
// public API for geometry objects

void dGeomDestroy (dxGeom *g)
{
    dAASSERT (g);
    delete g;
}


void dGeomSetData (dxGeom *g, void *data)
{
    dAASSERT (g);
    g->data = data;
}


void *dGeomGetData (dxGeom *g)
{
    dAASSERT (g);
    return g->data;
}


void dGeomSetBody (dxGeom *g, dxBody *b)
{
    dAASSERT (g);
    dUASSERT (b == NULL || (g->gflags & GEOM_PLACEABLE),"geom must be placeable");
    CHECK_NOT_LOCKED (g->parent_space);

    if (b) {
        if (!g->body) dFreePosr(g->final_posr);
        if (g->body != b) {
            if (g->offset_posr) {
                dFreePosr(g->offset_posr);
                g->offset_posr = 0;
            }
            g->final_posr = &b->posr;
            g->bodyRemove();
            g->bodyAdd (b);
        }
        dGeomMoved (g);
    }
    else {
        if (g->body) {
            if (g->offset_posr)
            {
                // if we're offset, we already have our own final position, make sure its updated
                g->recomputePosr();
                dFreePosr(g->offset_posr);
                g->offset_posr = 0;
            }
            else
            {
                g->final_posr = dAllocPosr();
                memcpy (g->final_posr->pos,g->body->posr.pos,sizeof(dVector3));
                memcpy (g->final_posr->R,g->body->posr.R,sizeof(dMatrix3));
            }
            g->bodyRemove();
        }
        // dGeomMoved() should not be called if the body is being set to 0, as the
        // new position of the geom is set to the old position of the body, so the
        // effective position of the geom remains unchanged.
    }
}


dBodyID dGeomGetBody (dxGeom *g)
{
    dAASSERT (g);
    return g->body;
}


void dGeomSetPosition (dxGeom *g, dReal x, dReal y, dReal z)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    CHECK_NOT_LOCKED (g->parent_space);
    if (g->offset_posr) {
        // move body such that body+offset = position
        dVector3 world_offset;
        dMultiply0_331(world_offset, g->body->posr.R, g->offset_posr->pos);
        dBodySetPosition(g->body,
            x - world_offset[0],
            y - world_offset[1],
            z - world_offset[2]);
    }
    else if (g->body) {
        // this will call dGeomMoved (g), so we don't have to
        dBodySetPosition (g->body,x,y,z);
    }
    else {
        g->final_posr->pos[0] = x;
        g->final_posr->pos[1] = y;
        g->final_posr->pos[2] = z;
        dGeomMoved (g);
    }
}


void dGeomSetRotation (dxGeom *g, const dMatrix3 R)
{
    dAASSERT (g && R);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    CHECK_NOT_LOCKED (g->parent_space);
    if (g->offset_posr) {
        g->recomputePosr();
        // move body such that body+offset = rotation
        dxPosR new_final_posr;
        dxPosR new_body_posr;
        memcpy(new_final_posr.pos, g->final_posr->pos, sizeof(dVector3));
        memcpy(new_final_posr.R, R, sizeof(dMatrix3));
        getBodyPosr(*g->offset_posr, new_final_posr, new_body_posr);
        dBodySetRotation(g->body, new_body_posr.R);
        dBodySetPosition(g->body, new_body_posr.pos[0], new_body_posr.pos[1], new_body_posr.pos[2]);
    }
    else if (g->body) {
        // this will call dGeomMoved (g), so we don't have to
        dBodySetRotation (g->body,R);
    }
    else {
        memcpy (g->final_posr->R,R,sizeof(dMatrix3));
        dGeomMoved (g);
    }
}


void dGeomSetQuaternion (dxGeom *g, const dQuaternion quat)
{
    dAASSERT (g && quat);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    CHECK_NOT_LOCKED (g->parent_space);
    if (g->offset_posr) {
        g->recomputePosr();
        // move body such that body+offset = rotation
        dxPosR new_final_posr;
        dxPosR new_body_posr;
        dQtoR (quat, new_final_posr.R);
        memcpy(new_final_posr.pos, g->final_posr->pos, sizeof(dVector3));

        getBodyPosr(*g->offset_posr, new_final_posr, new_body_posr);
        dBodySetRotation(g->body, new_body_posr.R);
        dBodySetPosition(g->body, new_body_posr.pos[0], new_body_posr.pos[1], new_body_posr.pos[2]);
    }
    if (g->body) {
        // this will call dGeomMoved (g), so we don't have to
        dBodySetQuaternion (g->body,quat);
    }
    else {
        dQtoR (quat, g->final_posr->R);
        dGeomMoved (g);
    }
}


const dReal * dGeomGetPosition (dxGeom *g)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    g->recomputePosr();
    return g->final_posr->pos;
}


void dGeomCopyPosition(dxGeom *g, dVector3 pos)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    g->recomputePosr();
    const dReal* src = g->final_posr->pos;
    pos[0] = src[0];
    pos[1] = src[1];
    pos[2] = src[2];
}


const dReal * dGeomGetRotation (dxGeom *g)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    g->recomputePosr();
    return g->final_posr->R;
}


void dGeomCopyRotation(dxGeom *g, dMatrix3 R)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    g->recomputePosr();
    const dReal* src = g->final_posr->R;
    R[0]  = src[0];
    R[1]  = src[1];
    R[2]  = src[2];
    R[4]  = src[4];
    R[5]  = src[5];
    R[6]  = src[6];
    R[8]  = src[8];
    R[9]  = src[9];
    R[10] = src[10];
}


void dGeomGetQuaternion (dxGeom *g, dQuaternion quat)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    if (g->body && !g->offset_posr) {
        const dReal * body_quat = dBodyGetQuaternion (g->body);
        quat[0] = body_quat[0];
        quat[1] = body_quat[1];
        quat[2] = body_quat[2];
        quat[3] = body_quat[3];
    }
    else {
        g->recomputePosr();
        dRtoQ (g->final_posr->R, quat);
    }
}


void dGeomGetAABB (dxGeom *g, dReal aabb[6])
{
    dAASSERT (g);
    dAASSERT (aabb);
    g->recomputeAABB();
    memcpy (aabb,g->aabb,6 * sizeof(dReal));
}


int dGeomIsSpace (dxGeom *g)
{
    dAASSERT (g);
    return IS_SPACE(g);
}


dSpaceID dGeomGetSpace (dxGeom *g)
{
    dAASSERT (g);
    return g->parent_space;
}


int dGeomGetClass (dxGeom *g)
{
    dAASSERT (g);
    return g->type;
}


void dGeomSetCategoryBits (dxGeom *g, unsigned long bits)
{
    dAASSERT (g);
    CHECK_NOT_LOCKED (g->parent_space);
    g->category_bits = bits;
}


void dGeomSetCollideBits (dxGeom *g, unsigned long bits)
{
    dAASSERT (g);
    CHECK_NOT_LOCKED (g->parent_space);
    g->collide_bits = bits;
}


unsigned long dGeomGetCategoryBits (dxGeom *g)
{
    dAASSERT (g);
    return g->category_bits;
}


unsigned long dGeomGetCollideBits (dxGeom *g)
{
    dAASSERT (g);
    return g->collide_bits;
}


void dGeomEnable (dxGeom *g)
{
    dAASSERT (g);
    g->gflags |= GEOM_ENABLED;
}

void dGeomDisable (dxGeom *g)
{
    dAASSERT (g);
    g->gflags &= ~GEOM_ENABLED;
}

int dGeomIsEnabled (dxGeom *g)
{
    dAASSERT (g);
    return (g->gflags & GEOM_ENABLED) != 0;
}


void dGeomGetRelPointPos (dGeomID g, dReal px, dReal py, dReal pz, dVector3 result)
{
    dAASSERT (g);

    if ((g->gflags & GEOM_PLACEABLE) == 0) {
        result[0] = px;
        result[1] = py;
        result[2] = pz;
        return;
    }

    g->recomputePosr();

    dVector3 prel,p;
    prel[0] = px;
    prel[1] = py;
    prel[2] = pz;
    prel[3] = 0;
    dMultiply0_331 (p,g->final_posr->R,prel);
    result[0] = p[0] + g->final_posr->pos[0];
    result[1] = p[1] + g->final_posr->pos[1];
    result[2] = p[2] + g->final_posr->pos[2];
}


void dGeomGetPosRelPoint (dGeomID g, dReal px, dReal py, dReal pz, dVector3 result)
{
    dAASSERT (g);
    if ((g->gflags & GEOM_PLACEABLE) == 0) {
        result[0] = px;
        result[1] = py;
        result[2] = pz;
        return;
    }

    g->recomputePosr();

    dVector3 prel;
    prel[0] = px - g->final_posr->pos[0];
    prel[1] = py - g->final_posr->pos[1];
    prel[2] = pz - g->final_posr->pos[2];
    prel[3] = 0;
    dMultiply1_331 (result,g->final_posr->R,prel);
}


void dGeomVectorToWorld (dGeomID g, dReal px, dReal py, dReal pz, dVector3 result)
{
    dAASSERT (g);
    if ((g->gflags & GEOM_PLACEABLE) == 0) {
        result[0] = px;
        result[1] = py;
        result[2] = pz;
        return;
    }

    g->recomputePosr();

    dVector3 p;
    p[0] = px;
    p[1] = py;
    p[2] = pz;
    p[3] = 0;
    dMultiply0_331 (result,g->final_posr->R,p);
}


void dGeomVectorFromWorld (dGeomID g, dReal px, dReal py, dReal pz, dVector3 result)
{
    dAASSERT (g);
    if ((g->gflags & GEOM_PLACEABLE) == 0) {
        result[0] = px;
        result[1] = py;
        result[2] = pz;
        return;
    }

    g->recomputePosr();

    dVector3 p;
    p[0] = px;
    p[1] = py;
    p[2] = pz;
    p[3] = 0;
    dMultiply1_331 (result,g->final_posr->R,p);
}



int dGeomLowLevelControl (dxGeom *g, int controlClass, int controlCode, void *dataValue, int *dataSize)
{
    dAASSERT (g);
    dAASSERT (dataSize);

    if (!dataSize) {
        return false;
    }

    bool result = g->controlGeometry(controlClass, controlCode, dataValue, dataSize);
    return result;
}

//****************************************************************************
// C interface that lets the user make new classes. this interface is a lot
// more cumbersome than C++ subclassing, which is what is used internally
// in ODE. this API is mainly to support legacy code.

static int num_user_classes = 0;
static dGeomClass user_classes [dMaxUserClasses];


struct dxUserGeom : public dxGeom {
    void *user_data;

    dxUserGeom (int class_num);
    ~dxUserGeom();
    void computeAABB();
    int AABBTest (dxGeom *o, dReal aabb[6]);
};


dxUserGeom::dxUserGeom (int class_num) : dxGeom (0,1)
{
    type = class_num;
    int size = user_classes[type-dFirstUserClass].bytes;
    user_data = dAlloc (size);
    memset (user_data,0,size);
}


dxUserGeom::~dxUserGeom()
{
    dGeomClass *c = &user_classes[type-dFirstUserClass];
    if (c->dtor) c->dtor (this);
    dFree (user_data,c->bytes);
}


void dxUserGeom::computeAABB()
{
    user_classes[type-dFirstUserClass].aabb (this,aabb);
}


int dxUserGeom::AABBTest (dxGeom *o, dReal aabb[6])
{
    dGeomClass *c = &user_classes[type-dFirstUserClass];
    if (c->aabb_test) return c->aabb_test (this,o,aabb);
    else return 1;
}


static int dCollideUserGeomWithGeom (dxGeom *o1, dxGeom *o2, int flags, dContactGeom *contact, int skip)
{
    // this generic collider function is called the first time that a user class
    // tries to collide against something. it will find out the correct collider
    // function and then set the colliders array so that the correct function is
    // called directly the next time around.

    int t1 = o1->type;	// note that o1 is a user geom
    int t2 = o2->type;	// o2 *may* be a user geom

    // find the collider function to use. if o1 does not know how to collide with
    // o2, then o2 might know how to collide with o1 (provided that it is a user
    // geom).
    dColliderFn *fn = user_classes[t1-dFirstUserClass].collider (t2);
    int reverse = 0;
    if (!fn && t2 >= dFirstUserClass && t2 <= dLastUserClass) {
        fn = user_classes[t2-dFirstUserClass].collider (t1);
        reverse = 1;
    }

    // set the colliders array so that the correct function is called directly
    // the next time around. note that fn can be 0 here if no collider was found,
    // which means that dCollide() will always return 0 for this case.
    colliders[t1][t2].fn = fn;
    colliders[t1][t2].reverse = reverse;
    colliders[t2][t1].fn = fn;
    colliders[t2][t1].reverse = !reverse;

    // now call the collider function indirectly through dCollide(), so that
    // contact reversing is properly handled.
    return dCollide (o1,o2,flags,contact,skip);
}


int dCreateGeomClass (const dGeomClass *c)
{
    dUASSERT(c && c->bytes >= 0 && c->collider && c->aabb,"bad geom class");

    if (num_user_classes >= dMaxUserClasses) {
        dDebug (0,"too many user classes, you must increase the limit and "
            "recompile ODE");
    }
    user_classes[num_user_classes] = *c;
    int class_number = num_user_classes + dFirstUserClass;
    setAllColliders (class_number,&dCollideUserGeomWithGeom);

    num_user_classes++;
    return class_number;
}

/*extern */void dFinitUserClasses()
{
    num_user_classes = 0;
}

void * dGeomGetClassData (dxGeom *g)
{
    dUASSERT (g && g->type >= dFirstUserClass &&
        g->type <= dLastUserClass,"not a custom class");
    dxUserGeom *user = (dxUserGeom*) g;
    return user->user_data;
}


dGeomID dCreateGeom (int classnum)
{
    dUASSERT (classnum >= dFirstUserClass &&
        classnum <= dLastUserClass,"not a custom class");
    return new dxUserGeom (classnum);
}



/* ************************************************************************ */
/* geom offset from body */

void dGeomCreateOffset (dxGeom *g)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    dUASSERT (g->body, "geom must be on a body");  
    if (g->offset_posr)
    {
        return; // already created
    }
    dIASSERT (g->final_posr == &g->body->posr);

    g->final_posr = dAllocPosr();
    g->offset_posr = dAllocPosr();
    dSetZero (g->offset_posr->pos,4);
    dRSetIdentity (g->offset_posr->R);

    g->gflags |= GEOM_POSR_BAD;
}

void dGeomSetOffsetPosition (dxGeom *g, dReal x, dReal y, dReal z)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    dUASSERT (g->body, "geom must be on a body");  
    CHECK_NOT_LOCKED (g->parent_space);
    if (!g->offset_posr) 
    {
        dGeomCreateOffset(g);
    }
    g->offset_posr->pos[0] = x;
    g->offset_posr->pos[1] = y;
    g->offset_posr->pos[2] = z;
    dGeomMoved (g);
}

void dGeomSetOffsetRotation (dxGeom *g, const dMatrix3 R)
{
    dAASSERT (g && R);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    dUASSERT (g->body, "geom must be on a body");  
    CHECK_NOT_LOCKED (g->parent_space);
    if (!g->offset_posr) 
    {
        dGeomCreateOffset (g);
    }
    memcpy (g->offset_posr->R,R,sizeof(dMatrix3));
    dGeomMoved (g);
}

void dGeomSetOffsetQuaternion (dxGeom *g, const dQuaternion quat)
{
    dAASSERT (g && quat);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    dUASSERT (g->body, "geom must be on a body");  
    CHECK_NOT_LOCKED (g->parent_space);
    if (!g->offset_posr) 
    {
        dGeomCreateOffset (g);
    }
    dQtoR (quat, g->offset_posr->R);
    dGeomMoved (g);
}

void dGeomSetOffsetWorldPosition (dxGeom *g, dReal x, dReal y, dReal z)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    dUASSERT (g->body, "geom must be on a body");  
    CHECK_NOT_LOCKED (g->parent_space);
    if (!g->offset_posr) 
    {
        dGeomCreateOffset(g);
    }
    dBodyGetPosRelPoint(g->body, x, y, z, g->offset_posr->pos);
    dGeomMoved (g);
}

void dGeomSetOffsetWorldRotation (dxGeom *g, const dMatrix3 R)
{
    dAASSERT (g && R);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    dUASSERT (g->body, "geom must be on a body");  
    CHECK_NOT_LOCKED (g->parent_space);
    if (!g->offset_posr) 
    {
        dGeomCreateOffset (g);
    }
    g->recomputePosr();

    dxPosR new_final_posr;
    memcpy(new_final_posr.pos, g->final_posr->pos, sizeof(dVector3));
    memcpy(new_final_posr.R, R, sizeof(dMatrix3));

    getWorldOffsetPosr(g->body->posr, new_final_posr, *g->offset_posr);
    dGeomMoved (g);
}

void dGeomSetOffsetWorldQuaternion (dxGeom *g, const dQuaternion quat)
{
    dAASSERT (g && quat);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    dUASSERT (g->body, "geom must be on a body");  
    CHECK_NOT_LOCKED (g->parent_space);
    if (!g->offset_posr) 
    {
        dGeomCreateOffset (g);
    }

    g->recomputePosr();

    dxPosR new_final_posr;
    memcpy(new_final_posr.pos, g->final_posr->pos, sizeof(dVector3));
    dQtoR (quat, new_final_posr.R);

    getWorldOffsetPosr(g->body->posr, new_final_posr, *g->offset_posr);
    dGeomMoved (g);
}

void dGeomClearOffset(dxGeom *g)
{
    dAASSERT (g);
    dUASSERT (g->gflags & GEOM_PLACEABLE,"geom must be placeable");
    if (g->offset_posr)
    {
        dIASSERT(g->body);
        // no longer need an offset posr
        dFreePosr(g->offset_posr);
        g->offset_posr = 0;
        // the geom will now share the position of the body
        dFreePosr(g->final_posr);
        g->final_posr = &g->body->posr;
        // geom has moved
        g->gflags &= ~GEOM_POSR_BAD;
        dGeomMoved (g);
    }
}

int dGeomIsOffset(dxGeom *g)
{
    dAASSERT (g);
    return ((0 != g->offset_posr) ? 1 : 0);
}

static const dVector3 OFFSET_POSITION_ZERO = { 0.0f, 0.0f, 0.0f, 0.0f };

const dReal * dGeomGetOffsetPosition (dxGeom *g)
{
    dAASSERT (g);
    if (g->offset_posr)
    {
        return g->offset_posr->pos;
    }
    return OFFSET_POSITION_ZERO;
}

void dGeomCopyOffsetPosition (dxGeom *g, dVector3 pos)
{
    dAASSERT (g);
    if (g->offset_posr)
    {
        const dReal* src = g->offset_posr->pos;
        pos[0] = src[0];
        pos[1] = src[1];
        pos[2] = src[2];
    }
    else
    {
        pos[0] = 0;
        pos[1] = 0;
        pos[2] = 0;
    }
}

static const dMatrix3 OFFSET_ROTATION_ZERO = 
{ 
    1.0f, 0.0f, 0.0f, 0.0f, 
    0.0f, 1.0f, 0.0f, 0.0f, 
    0.0f, 0.0f, 1.0f, 0.0f, 
};

const dReal * dGeomGetOffsetRotation (dxGeom *g)
{
    dAASSERT (g);
    if (g->offset_posr)
    {
        return g->offset_posr->R;
    }
    return OFFSET_ROTATION_ZERO;
}

void dGeomCopyOffsetRotation (dxGeom *g, dMatrix3 R)
{
    dAASSERT (g);
    if (g->offset_posr)
    {
        const dReal* src = g->offset_posr->R;
        R[0]  = src[0];
        R[1]  = src[1];
        R[2]  = src[2];
        R[4]  = src[4];
        R[5]  = src[5];
        R[6]  = src[6];
        R[8]  = src[8];
        R[9]  = src[9];
        R[10] = src[10];
    }
    else
    {
        R[0]  = OFFSET_ROTATION_ZERO[0];
        R[1]  = OFFSET_ROTATION_ZERO[1];
        R[2]  = OFFSET_ROTATION_ZERO[2];
        R[4]  = OFFSET_ROTATION_ZERO[4];
        R[5]  = OFFSET_ROTATION_ZERO[5];
        R[6]  = OFFSET_ROTATION_ZERO[6];
        R[8]  = OFFSET_ROTATION_ZERO[8];
        R[9]  = OFFSET_ROTATION_ZERO[9];
        R[10] = OFFSET_ROTATION_ZERO[10];
    }
}

void dGeomGetOffsetQuaternion (dxGeom *g, dQuaternion result)
{
    dAASSERT (g);
    if (g->offset_posr)
    {
        dRtoQ (g->offset_posr->R, result);
    }
    else
    {
        dSetZero (result,4);
        result[0] = 1;
    }
}


