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From: "K.Tamura" <kouzou@ymg.urban.or.jp>
Newsgroups: playstation.ny.test
Subject: =?iso-2022-jp?B?GyRCJCokXiQxJTMhPCVKITwbKEo=?=
Date: Sat, 27 Sep 1997 21:55:52 +0900
Organization: PlayStation Net Yarouze
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　暇な人は関数ポインタのテーブル使う方式に
　直して遊んでください(笑)
　atanのテーブルは自分で作るべし。


int GetAngle( long dx, long dy ){

        unsigned int    index = 0;
        int     angle;
        int distance;


        if ( dx == 0 ){
                if ( dy < 0 ){
                        return (192);
                }else{
                        return (64);
                }
        }
        if ( dy == 0 ){
                if ( dx < 0 ){
                        return (128);
                }else{
                        return (0);
                }
        }

        if ( dy < 0 ){
                index |= 4;
                dy = - dy;
        }
        if ( dx < 0 ){
                index |= 2;
                dx = -dx;
        }
        if ( dx < dy ) index |= 1;

        switch ( index ){
                case 0:{
                        angle = atan_tbl[ (dy<<8)/dx ];                
/* 0 */
                        break;
                }
                case 1:{
                        angle = 64 - atan_tbl[ (dx<<8)/dy ];           
/* 1 */
                        break;
                }
                case 2:{
                        angle = 128 - atan_tbl[ (dy<<8)/dx ];          
/* 3 */
                        break;
                }
                case 3:{
                        angle = 64 + atan_tbl[ (dx<<8)/dy ];           
/* 2 */
                        break;
                }
                case 4:{
                        angle = 256 - atan_tbl[ (dy<<8)/dx ];          
/* 7 */
                        break;
                }
                case 5:{
                        angle = 192 + atan_tbl[ (dx<<8)/dy ];          
/* 6 */
                        break;
                }
                case 6:{
                        angle = 128 + atan_tbl[ (dy<<8)/dx ];          
/* 4 */
                        break;
                }
                case 7:{
                        angle = 192 - atan_tbl[ (dx<<8)/dy ];          
/* 5 */
                        break;
                }
        }                               

        return ( angle );
}