JointTransform.cpp

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/*
===========================================================================

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).  

Doom 3 Source Code is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Doom 3 Source Code 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with Doom 3 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

===========================================================================
*/

#include "../precompiled.h"
#pragma hdrstop


/*
=============
idJointMat::ToJointQuat
=============
*/
idJointQuat idJointMat::ToJointQuat( void ) const {
        idJointQuat     jq;
        float           trace;
        float           s;
        float           t;
        int             i;
        int                     j;
        int                     k;

        static int      next[3] = { 1, 2, 0 };

        trace = mat[0 * 4 + 0] + mat[1 * 4 + 1] + mat[2 * 4 + 2];

        if ( trace > 0.0f ) {

                t = trace + 1.0f;
                s = idMath::InvSqrt( t ) * 0.5f;

                jq.q[3] = s * t;
                jq.q[0] = ( mat[1 * 4 + 2] - mat[2 * 4 + 1] ) * s;
                jq.q[1] = ( mat[2 * 4 + 0] - mat[0 * 4 + 2] ) * s;
                jq.q[2] = ( mat[0 * 4 + 1] - mat[1 * 4 + 0] ) * s;

        } else {

                i = 0;
                if ( mat[1 * 4 + 1] > mat[0 * 4 + 0] ) {
                        i = 1;
                }
                if ( mat[2 * 4 + 2] > mat[i * 4 + i] ) {
                        i = 2;
                }
                j = next[i];
                k = next[j];

                t = ( mat[i * 4 + i] - ( mat[j * 4 + j] + mat[k * 4 + k] ) ) + 1.0f;
                s = idMath::InvSqrt( t ) * 0.5f;

                jq.q[i] = s * t;
                jq.q[3] = ( mat[j * 4 + k] - mat[k * 4 + j] ) * s;
                jq.q[j] = ( mat[i * 4 + j] + mat[j * 4 + i] ) * s;
                jq.q[k] = ( mat[i * 4 + k] + mat[k * 4 + i] ) * s;
        }

        jq.t[0] = mat[0 * 4 + 3];
        jq.t[1] = mat[1 * 4 + 3];
        jq.t[2] = mat[2 * 4 + 3];

        return jq;
}