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/***************************************************************************
mathfuncs.c - description
-------------------
begin : Thu Sep 6 2001
copyright : (C) 2001 by Michael Speck
email : kulkanie@gmx.net
***************************************************************************/
/***************************************************************************
* *
* 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 3 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#include "gamedefs.h"
#include "mathfuncs.h"
/*
====================================================================
Return vector struct with the specified coordinates.
====================================================================
*/
Vector vector_get( double x, double y )
{
Vector v = { x, y };
return v;
}
/*
====================================================================
Give vector the normed length of 1.
====================================================================
*/
void vector_norm( Vector *v )
{
double length;
if ( v->x == 0 && v->y == 0 ) return; /* NULL vector may not be normed */
length = sqrt( v->x * v->x + v->y * v->y );
v->x /= length;
v->y /= length;
}
/*
====================================================================
Return monotony of vector. If vertical return 0
====================================================================
*/
double vector_monotony( Vector v )
{
if ( v.x == 0 ) return 0;
return v.y / v.x;
}
/*
====================================================================
Set length of a vector.
====================================================================
*/
void vector_set_length( Vector *v, double length )
{
vector_norm( v );
v->x *= length; v->y *= length;
}
/*
====================================================================
Initiate a line struct.
====================================================================
*/
void line_set( Line *line, double x, double y, double m )
{
line->vertical = 0;
line->m = m;
line->n = y - m*x;
}
void line_set_vert( Line *line, double x )
{
line->vertical = 1;
line->x = x;
}
void line_set_hori( Line *line, double y )
{
line->vertical = 0;
line->m = 0;
line->n = y;
}
/*
====================================================================
Intersect lines and set 'pos' to intersecting point.
Return Value: True if lines intersect.
====================================================================
*/
int line_intersect( Line *line, Line *target, Coord *pos )
{
/* reset pos */
pos->x = pos->y = 0;
/* if lines are parallel return False */
if ( line->vertical && target->vertical ) return 0; /* vertical parallels */
if ( !line->vertical && !target->vertical && line->m == target->m ) return 0; /* non-vertical parallels */
/* right now only one thing is supported: line horizontal */
if ( line->m == 0 && line->vertical == 0 ) {
pos->y = line->n;
if ( target->vertical )
pos->x = target->x;
else
pos->x = ( pos->y - target->n ) / target->m;
return 1;
}
if ( line->vertical ) {
if ( target->vertical ) return 0;
pos->x = line->x;
pos->y = target->m * pos->x + target->n;
return 1;
}
if ( target->vertical ) {
printf( "line_intersect: line non-vertical and target vertical not supported yet\n" );
return 1;
}
/* compute if both lines are neither vertical nor horizontal */
pos->x = ( line->n - target->n ) / ( target->m - line->m );
pos->y = line->m * pos->x + line->n;
return 1;
}
/*
====================================================================
Initiate a line struct.
====================================================================
*/
void iline_set( ILine *line, int x, int y, int m_4096 )
{
line->vertical = 0;
line->m_4096 = m_4096;
line->n = y - ((m_4096*x)>>12);
}
void iline_set_vert( ILine *line, int x )
{
line->vertical = 1;
line->x = x;
}
void iline_set_hori( ILine *line, int y )
{
line->vertical = 0;
line->m_4096 = 0;
line->n = y;
}
/*
====================================================================
Intersect lines and set 'pos' to intersecting point.
Return Value: True if lines intersect.
====================================================================
*/
int iline_intersect( ILine *line, ILine *target, ICoord *pos )
{
/* reset pos */
pos->x = pos->y = 0;
/* if lines are parallel return False */
if ( line->vertical && target->vertical ) return 0; /* vertical parallels */
if ( !line->vertical && !target->vertical )
if ( line->m_4096 == target->m_4096 ) return 0; /* non-vertical parallels */
/* right now only one thing is supported: line horizontal */
if ( line->m_4096 == 0 && line->vertical == 0 ) {
pos->y = line->n;
if ( target->vertical )
pos->x = target->x;
else
pos->x = (( pos->y - target->n )<<12) / target->m_4096;
return 1;
}
if ( line->vertical ) {
if ( target->vertical ) return 0;
pos->x = line->x;
pos->y = ((target->m_4096 * pos->x)>>12) + target->n;
return 1;
}
if ( target->vertical ) {
printf( "line_intersect: line non-vertical and target vertical not supported yet\n" );
return 1;
}
/* compute if both lines are neither vertical nor horizontal */
pos->x = (( line->n - target->n )<<12) / ( target->m_4096 - line->m_4096 );
pos->y = ((line->m_4096 * pos->x)>>12) + line->n;
return 1;
}
/*
====================================================================
Intersect line pos+t*v with circle (x+m)�=r�
Important length of v MUST be 1.
Return Value: True if intersecting, Intersecting points
====================================================================
*/
int circle_intersect( Vector m, int r, Vector pos, Vector v, Vector *t1, Vector *t2 )
{
Vector delta = { pos.x - m.x, pos.y - m.y };
double delta_v = delta.x * v.x + delta.y * v.y;
double dis = delta_v * delta_v + r * r - ( delta.x * delta.x + delta.y * delta.y );
double t;
if (dis < 0)
return 0;
dis = sqrt(dis);
t = -delta_v + dis;
t1->x = pos.x + t * v.x; t1->y = pos.y + t * v.y;
t = -delta_v - dis;
t2->x = pos.x + t * v.x; t2->y = pos.y + t * v.y;
return 1;
}
/* convert vector to angle/2 0-180 and vice versa */
static Vector impact_vectors[180]; /* clockwise impact vectors in 2 degree steps */
void init_angles( void )
{
int i;
/* create vectors for all degrees in 2� steps */
for ( i = 0; i < 180; i++ ) {
impact_vectors[i].x = cos( 6.28 * i / 180 );
impact_vectors[i].y = sin( 6.28 * i / 180 );
}
}
int vec2angle( Vector *vec )
{
int degrees = 0;
/* translate impact vector (src-center) into degrees
* (0�: horizontally right, clockwise going) */
if ( vec->x == 0 )
degrees = 90; /* basically impossible as we mask this out */
else
degrees = (int)(360 * atan( (double)(fabs(vec->y))/fabs(vec->x) ) / 6.28);
/* get the proper quartal */
if ( vec->x > 0 ) {
if ( vec->y < 0 )
degrees = 360 - degrees;
}
else {
if ( vec->y >= 0 )
degrees = 180 - degrees;
else
degrees = 180 + degrees;
}
return degrees/2;
}
void angle2vec( int angle, Vector *vec )
{
vec->x = 0;
vec->y = 0;
if ( angle < 0 ) return;
if ( angle > 179 ) return;
*vec = impact_vectors[angle];
}
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