vec2.c

/*
 * See Licensing and Copyright notice in naev.h
 */
#include "vec2.h"

void vec2_cset( vec2 *v, double x, double y )
{
   v->x     = x;
   v->y     = y;
   v->mod   = MOD( x, y );
   v->angle = ANGLE( x, y );
}

void vec2_csetmin( vec2 *v, double x, double y )
{
   v->x = x;
   v->y = y;
}

void vec2_pset( vec2 *v, double mod, double angle )
{
   v->mod   = mod;
   v->angle = angle;
   v->x     = v->mod * cos( v->angle );
   v->y     = v->mod * sin( v->angle );
}

void vectnull( vec2 *v )
{
   v->x     = 0.;
   v->y     = 0.;
   v->mod   = 0.;
   v->angle = 0.;
}

double vec2_angle( const vec2 *ref, const vec2 *v )
{
   double x = v->x - ref->x;
   double y = v->y - ref->y;
   return ANGLE( x, y );
}

void vec2_cadd( vec2 *v, double x, double y )
{
   v->x += x;
   v->y += y;
   v->mod   = MOD( v->x, v->y );
   v->angle = ANGLE( v->x, v->y );
}

void vec2_padd( vec2 *v, double m, double a )
{
   v->x += m * cos( a );
   v->y += m * sin( a );
   v->mod   = MOD( v->x, v->y );
   v->angle = ANGLE( v->x, v->y );
}

void vec2_reflect( vec2 *r, const vec2 *v, const vec2 *n )
{
   double dot = vec2_dot( v, n );
   r->x       = v->x - ( ( 2. * dot ) * n->x );
   r->y       = v->y - ( ( 2. * dot ) * n->y );
   r->mod     = MOD( r->x, r->y );
   r->angle   = ANGLE( r->x, r->y );
}

double vec2_dot( const vec2 *a, const vec2 *b )
{
   return a->x * b->x + a->y * b->y;
}

void vec2_uv( double *u, double *v, const vec2 *source,
              const vec2 *reference_vector )
{
   vec2 unit_parallel, unit_perpendicular;
 
   vec2_uv_decomp( &unit_parallel, &unit_perpendicular, reference_vector );
 
   *u = vec2_dot( source, &unit_parallel );
   *v = vec2_dot( source, &unit_perpendicular );
}

void vec2_uv_decomp( vec2 *u, vec2 *v, const vec2 *reference_vector )
{
   vec2_pset( u, 1, VANGLE( *reference_vector ) );
   vec2_pset( v, 1, VANGLE( *reference_vector ) + M_PI_2 );
}