modules/base/math/geometry/vect_base.c

   1 #include <stdint.h>
   2 #include <math.h>
   3 #include <vect_base.h>
   4
   5 /* Return scalar product */
   6 int32_t
   7 vect_pscal(vect_t *v, vect_t *w)
   8 {
   9         return v->x * w->x + v->y * w->y;
  10 }
  11
  12 /* Return Z of vectorial product */
  13 int32_t
  14 vect_pvect(vect_t *v, vect_t *w)
  15 {
  16         return v->x*w->y - v->y*w->x;
  17 }
  18
  19 /* Return scalar product */
  20 int8_t
  21 vect_pscal_sign(vect_t *v, vect_t *w)
  22 {
  23         int32_t z;
  24         z = vect_pscal(v, w);
  25         if (z==0)
  26                 return 0;
  27         return z>0?1:-1;
  28 }
  29
  30 /* Return Z of vectorial product */
  31 int8_t
  32 vect_pvect_sign(vect_t *v, vect_t *w)
  33 {
  34         int32_t z;
  35         z = vect_pvect(v, w);
  36         if (z==0)
  37                 return 0;
  38         return z>0?1:-1;
  39 }
  40
  41 /* norm of a vector */
  42 float
  43 vect_norm(vect_t *v)
  44 {
  45         return sqrt(v->x*v->x+v->y*v->y);
  46 }
  47
  48
  49
  50 void vect_rot_trigo(vect_t *v)
  51 {
  52         int32_t s;
  53
  54         s = v->x;
  55         v->x= -v->y;
  56         v->y = s;
  57 }
  58
  59 void vect_rot_retro(vect_t *v)
  60 {
  61         int32_t s;
  62
  63         s = v->x;
  64         v->x= v->y;
  65         v->y = -s;
  66 }
  67
  68
  69 float vect_get_angle(vect_t *v, vect_t *w)
  70 {
  71         int32_t ps;
  72         float n;
  73
  74         ps = vect_pscal(v, w);
  75         n = vect_norm(v) * vect_norm(w);
  76
  77         return acos((float)ps/n);
  78 }