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/*
ssystem 1.6
Copyright (C) 1997-1999 Raul Alonso <amil@las.es>
This program 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 2 of the License, or
(at your option) any later version.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "ssystem.h"
/* A couple of functions borrowed from David Bucciarelli's demos */
void printstring(void *font, char *string)
{
int i=0;
while (string[i])
glutBitmapCharacter(font,string[i++]);
}
float gettime(void)
{
static float told=0.0f;
float tnew,ris;
tnew=glutGet(GLUT_ELAPSED_TIME);
ris=tnew-told;
told=tnew;
return ris/1000.0;
}
/* Rotates (rx,ry,rz) point about the (ax,ay,az) axis 'angle' radians,
borrowed from Mesa */
void Rotation( double angle, double ax, double ay, double az,
double *rx, double *ry, double *rz)
{
double mag, s, c;
double x,y,z,xx, yy, zz, xy, yz, zx, xs, ys, zs, one_c;
s = sin(angle);
c = cos(angle);
mag = DISTANCE(ax,ay,az);
if (mag == 0.0) return;
x = ax/mag;
y = ay/mag;
z = az/mag;
xx = x * x;
yy = y * y;
zz = z * z;
xy = x * y;
yz = y * z;
zx = z * x;
xs = x * s;
ys = y * s;
zs = z * s;
one_c = 1.0 - c;
x = *rx*((one_c * xx) + c);
y = *rx*((one_c * xy) - zs);
z = *rx*((one_c * zx) + ys);
x += *ry*((one_c * xy) + zs);
y += *ry*((one_c * yy) + c);
z += *ry*((one_c * yz) - xs);
x += *rz*((one_c * zx) - ys);
y += *rz*((one_c * yz) + xs);
z += *rz*((one_c * zz) + c);
*rx=x; *ry=y; *rz=z;
}
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