/*
    Amiga port by Oliver Gantert

    28.04.2000 - fixed some compiler warnings
*/
/*

ORBIT, a freeware space combat simulator
Copyright (C) 1999  Steve Belczyk <steve1@genesis.nred.ma.us>

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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void RotateAbout (double *vp, double *v, double *n, double theta)
/*
 *  Rotate the vector v about the vector n by theta radians, leaving
 *  the rotated vector in vp.
 */
{
  double X, Y, Z, x, y, z, sintheta, costheta, t1, t2, t3, t4, t5;
  double t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17;
  double t18, t19, a, b, c, d, e, f, g, h, i;
  
  X = v[0];
  Y = v[1];
  Z = v[2];

  x = n[0];
  y = n[1];
  z = n[2];

  sintheta = sin (theta);
  costheta = cos (theta);

  t1 = x * x;
  t2 = y * y;
  t3 = z * z;

  t4 = 1.0 - t1;
  t5 = 1.0 - t2;
  t6 = 1.0 - t3;

  t7 = 1.0 - costheta;

  t8 = x * y;
  t9 = x * z;
  t10 = y * z;

  t11 = x * sintheta;
  t12 = y * sintheta;
  t13 = z * sintheta;

  t14 = t4 * costheta;
  t15 = t5 * costheta;
  t16 = t6 * costheta;

  t17 = t8 * t7;
  t18 = t9 * t7;
  t19 = t10 * t7;

  a = t1 + t14;
  b = t17 + t13;
  c = t18 - t12;

  d = t17 - t13;
  e = t2 + t15;
  f = t19 + t11;

  g = t18 + t12;
  h = t19 - t11;
  i = t3 + t16;

  vp[0] = X * a + Y * b + Z * c;
  vp[1] = X * d + Y * e + Z * f;
  vp[2] = X * g + Y * h + Z * i;
}

void Normalize (double *v)
{
  double Mag(), vt[3];
  Vdiv (vt, v, Mag(v));
  Vset (v, vt);
}

double Dotp (double *a, double *b)
{
  return (a[0]*b[0] + a[1]*b[1] + a[2]*b[2]);
}

double Mag (double *a)
{
  return ((double) sqrt ((double)(a[0]*a[0] + a[1]*a[1] + a[2]*a[2])));
}

double Mag2 (double *a)
{
  return (a[0]*a[0] + a[1]*a[1] + a[2]*a[2]);
}

void Vadd (double *a, double *b, double *c)
{
  a[0] = b[0] + c[0];
  a[1] = b[1] + c[1];
  a[2] = b[2] + c[2];
}

void Vsub (double *a, double *b, double *c)
{
  a[0] = b[0] - c[0];
  a[1] = b[1] - c[1];
  a[2] = b[2] - c[2];
}

void Crossp (double *c, double *a, double *b)
{
  c[0] = a[1]*b[2] - a[2]*b[1];
  c[1] = a[2]*b[0] - a[0]*b[2];
  c[2] = a[0]*b[1] - a[1]*b[0];
}

void Vdiv (double *a, double *b, double s)
{
  a[0] = b[0] / s;
  a[1] = b[1] / s;
  a[2] = b[2] / s;
}

void Vmul (double *a, double *b, double s)
{
  a[0] = b[0] * s;
  a[1] = b[1] * s;
  a[2] = b[2] * s;
}

void Vset (double *a, double *b)
{
  a[0] = b[0];
  a[1] = b[1];
  a[2] = b[2];
}

double Dist2 (double x1, double y1, double z1, double x2, double y2, double z2)
/*
 *  Squared distance between two points
 */
{
  double dx, dy, dz;

  dx = x1 - x2;
  dy = y1 - y2;
  dz = z1 - z2;

  return (dx*dx + dy*dy + dz*dz);
}

double rnd (double r)
/*
 *  Random double on [0..r]
 */
{
  int i;
  double f;

  i = (rand() & 0xffff);
  f = r * (((double)(i)) / 65536.0);

  return (f);
}

void OutOfMemory()
{
  Log ("OutOfMemory: Out of memory!  Panicking!!");
  FinishSound();
  CloseLog();
  exit (0);
}

void Perp (double *v1, double *v)
/*
 *  Find a vector v1 perpendicular to non-zero vector v
 *
 *  Based on the idea that the dot product of perpendicular vectors is zero
 */
{
  if ( (v[0] != 0.0) && (v[1] != 0.0) )
  {
    v1[0] = -1.0 / v[0];
    v1[1] =  1.0 / v[1];
    v1[2] = 0.0;
  }
  else if ( (v[1] != 0.0) && (v[2] != 0.0) )
  {
    v1[0] = 0.0;
    v1[1] = -1.0 / v[1];
    v1[2] =  1.0 / v[2];
  }
  else if ( (v[0] != 0.0) && (v[2] != 0.0) )
  {
    v1[0] = -1.0 / v[0];
    v1[1] = 0.0;
    v1[2] =  1.0 / v[2];
  }
  else if ( (v[0] == 0.0) && (v[1] == 0.0) && (v[2] != 0.0) )
  {
    v1[0] = 1.0;
    v1[1] = 0.0;
    v1[2] = 0.0;
  }
  else if ( (v[0] != 0.0) && (v[1] == 0.0) && (v[2] == 0.0) )
  {
    v1[0] = 0.0;
    v1[1] = 1.0;
    v1[2] = 0.0;
  }
  else if ( (v[0] == 0.0) && (v[1] != 0.0) && (v[2] == 0.0) )
  {
    v1[0] = 1.0;
    v1[1] = 0.0;
    v1[2] = 0.0;
  }
  else
  {
    /* Should never happen */
    v1[0] = 1.0;
    v1[1] = 0.0;
    v1[2] = 0.0;
  }
}