src/lib/math_vector.c

   1 /************************************************************************
   2 * math_vector.c
   3 * voxelands - 3d voxel world sandbox game
   4 * Copyright (C) Lisa 'darkrose' Milne 2016 <lisa@ltmnet.com>
   5 *
   6 * This program is free software: you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation, either version 3 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful, but
  12 * WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  14 * See the GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program.  If not, see <http://www.gnu.org/licenses/>
  18 ************************************************************************/
  19
  20 #include "common.h"
  21
  22 #include <math.h>
  23
  24 /* get a vector from start/end points */
  25 void vect_create(v3_t *start, v3_t *end, v3_t *v)
  26 {
  27         v->x = end->x - start->x;
  28         v->y = end->y - start->y;
  29         v->z = end->z - start->z;
  30         vect_normalise(v);
  31 }
  32
  33 /* get the length of a vector */
  34 float vect_length(v3_t *v)
  35 {
  36         return sqrtf(v->x*v->x + v->y*v->y + v->z*v->z);
  37 }
  38
  39 /* normalise a vector */
  40 void vect_normalise(v3_t *v)
  41 {
  42         float l;
  43         l= vect_length(v);
  44         if (l==0)
  45                 l = 1;
  46
  47         v->x/=l;
  48         v->y/=l;
  49         v->z/=l;
  50 }
  51
  52 /* get the scalar product of vectors */
  53 float vect_scalarproduct(v3_t *v1, v3_t *v2)
  54 {
  55     return (v1->x*v2->x + v1->y*v2->y + v1->z*v2->z);
  56 }
  57
  58 /* get the cross product of vectors */
  59 void vect_crossproduct(v3_t *v1, v3_t *v2, v3_t *v3)
  60 {
  61         v3->x=(v1->y*v2->z)-(v1->z*v2->y);
  62         v3->y=(v1->z*v2->x)-(v1->x*v2->z);
  63         v3->z=(v1->x*v2->y)-(v1->y*v2->x);
  64 }
  65
  66 /* get the dot product of vectors */
  67 void vect_dotproduct(v3_t *v1, v3_t *v2, v3_t *v3)
  68 {
  69         v3->x=(v1->y*v2->z)+(v1->z*v2->y);
  70         v3->y=(v1->z*v2->x)+(v1->x*v2->z);
  71         v3->z=(v1->x*v2->y)+(v1->y*v2->x);
  72 }
  73
  74 /* subtract a vector from a vector */
  75 void vect_subtract(v3_t *v1, v3_t *v2, v3_t *v3)
  76 {
  77         v3->x = (v1->x-v2->x);
  78         v3->y = (v1->y-v2->y);
  79         v3->z = (v1->z-v2->z);
  80 }
  81
  82 /* get the diameter of a vector */
  83 float vect_diameter(v3_t *v)
  84 {
  85         return sqrtf(vect_scalarproduct(v,v));
  86 }
  87
  88 /* get the dot product of vectors */
  89 float math_dotproduct(v3_t *v1, v3_t *v2)
  90 {
  91         return (v1->x*v2->x + v1->y*v2->y + v1->z*v2->z);
  92 }
  93
  94 /* get the distance between two points */
  95 float math_distance(v3_t *v1, v3_t *v2)
  96 {
  97         float xd = v2->x-v1->x;
  98         float yd = v2->y-v1->y;
  99         float zd = v2->z-v1->z;
 100
 101         if (xd < 0.0)
 102                 xd *= -1.0;
 103         if (yd < 0.0)
 104                 yd *= -1.0;
 105         if (zd < 0.0)
 106                 zd *= -1.0;
 107
 108         return sqrtf(xd*xd + yd*yd + zd*zd);
 109 }