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/*
Overgod
Copyright (C) 2005 Linley Henzell
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public Licence as published by
the Free Software Foundation; either version 2 of the Licence, 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 Licence for more details.
You should have received a copy of the GNU General Public Licence
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
The GPL version 2 is included in this distribution in a file called
LICENCE.TXT. Use any text editor or the TYPE command to read it.
You should be able to reach me by sending an email to
l_henzell@yahoo.com.au.
File: stuff.c
History:
11/9/2005 - Version 1.0 finalised
This file contains:
- a few common functions
*/
#include "allegro.h"
#include <math.h>
//#include <stdlib.h>
#include "config.h"
int turn_towards_angle(int angle, int tangle, int turning);
float lcos(int angle);
float lsin(int angle);
float angle_to_radians(int angle);
// I have no idea why, but the first few elements of cos_table always get corrupted
// unless I put a big fat decoy array just above. A similar thing happens to the
// palette arrays; there seems to be a problem with global arrays like these.
float decoy_table [ANGLE_FULL]; // not used
float cos_table [ANGLE_FULL];
float sin_table [ANGLE_FULL];
inline int xpart(int angle, int length);
void init_trig(void)
{
int i;
for (i = 0; i < ANGLE_FULL; i ++)
{
cos_table [i] = cos(angle_to_radians(i));// * ANGLE_FULL;
sin_table [i] = sin(angle_to_radians(i));// * ANGLE_FULL;
}
}
inline int xpart(int angle, int length)
{
// return (lcos(angle) * length);// / ANGLE_FULL;
return (cos_table [angle & 1023] * length);// / ANGLE_FULL;
}
inline int ypart(int angle, int length)
{
return (sin_table [angle & 1023] * length);// / ANGLE_FULL;
}
float lcos(int angle)
{
return cos_table [angle & 1023]; //0x4ffffffff];
}
float lsin(int angle)
{
return sin_table [angle & 1023]; //0x4ffffffff];
}
float angle_to_radians(int angle)
{
return ((float) angle * PI * 2) / ANGLE_FULL;
// return ((float) angle / ANGLE_FULL) * PI * 2;
}
int radians_to_angle(float angle)
{
return (int) ((angle * ANGLE_FULL) / (PI * 2));
}
fixed angle_to_fixed(int angle)
{
return itofix(angle / ANGLE_TO_FIXED);
}
int grand(int number)
{
if (number == 0)
return 0;
return ((rand() + (rand() << 16)) & 0x7fffffff) % number;
}
int crandom(int number)
{
if (number == 0)
return 0;
return ((rand() + (rand() << 16)) & 0x7fffffff) % number;
// return (rand() + (rand() << 16)) % number;
}
int turn_towards_angle(int angle, int tangle, int turning)
{
if ((angle < tangle && tangle > angle + ANGLE_HALF)
|| (angle > tangle && tangle > angle - ANGLE_HALF))
{
angle -= turning;
if (angle < 0)
angle += ANGLE_FULL;
}
else
{
angle += turning;
if (angle > ANGLE_FULL)
angle -= ANGLE_FULL;
}
return angle;
}
int turn_towards_xy(int x1, int y1, int x2, int y2, int angle, int turning)
{
int tangle =
radians_to_angle(atan2((y2 - y1), (x2 - x1)));
if (tangle < 0)
tangle += ANGLE_FULL;
if (tangle > ANGLE_FULL)
tangle -= ANGLE_FULL;
return turn_towards_angle(angle, tangle, turning);
}
// speed must be at least 4, and a factor of 1024
int pulsate(int speed, int amount, int county)
{
return xpart((county * speed) & 1023, amount);
}
void error_message_out(const char *errm)
{
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("%s", errm);
exit(1);
}
int angle_difference(int a1, int a2)
{
int d1, d2;
d1 = (a1 - a2 + ANGLE_FULL) % ANGLE_FULL;
d2 = (a2 - a1 + ANGLE_FULL) % ANGLE_FULL;
if (d1 < d2)
return abs(d1);
return abs(d2);
}
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