src/vec.h

   1 /*
   2         This file is part of cave9.
   3
   4         cave9 is free software: you can redistribute it and/or modify
   5         it under the terms of the GNU General Public License as published by
   6         the Free Software Foundation, either version 3 of the License, or
   7         (at your option) any later version.
   8
   9         cave9 is distributed in the hope that it will be useful,
  10         but WITHOUT ANY WARRANTY; without even the implied warranty of
  11         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12         GNU General Public License for more details.
  13
  14         You should have received a copy of the GNU General Public License
  15         along with cave9.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #ifndef math_h_included
  19 #define math_h_included
  20
  21 #include <SDL_opengl.h>
  22 #include <GL/gl.h>
  23
  24 #ifndef __cplusplus
  25   #ifndef bool
  26     typedef unsigned char bool;
  27     #define false 0
  28     #define true  1
  29   #endif
  30 #endif
  31
  32 #define EPSILON 0.000001
  33
  34 typedef GLfloat Vec3[3];
  35
  36 #define MAX(x,y) ((x)>(y)?(x):(y))
  37 #define MIN(x,y) ((x)<(y)?(x):(y))
  38 #define CLAMP(x,y,z) ((x)<(y)?(y):((x)>(z)?(z):(x)))
  39
  40 // FIXME parenthize
  41
  42 #define RAND (rand()/(float)RAND_MAX)
  43
  44 #define COPY(a,b) \
  45         a[0]=b[0]; \
  46         a[1]=b[1]; \
  47         a[2]=b[2];
  48
  49 #define CROSS(a,b,c) \
  50         a[0]=b[1]*c[2]-b[2]*c[1]; \
  51         a[1]=b[2]*c[0]-b[0]*c[2]; \
  52         a[2]=b[0]*c[1]-b[1]*c[0];
  53
  54 #define DOT(a,b) \
  55         (a[0]*b[0]+a[1]*b[1]+a[2]*b[2])
  56
  57 #define ADD2(a,b,c) \
  58         a[0]=b[0]+c[0]; \
  59         a[1]=b[1]+c[1]; \
  60         a[2]=b[2]+c[2];
  61
  62 #define ADD(a,b) \
  63         a[0]+=b[0]; \
  64         a[1]+=b[1]; \
  65         a[2]+=b[2];
  66
  67 #define ADDSCALE(a,b,x) \
  68         a[0]+=b[0]*x; \
  69         a[1]+=b[1]*x; \
  70         a[2]+=b[2]*x;
  71
  72 #define SUB2(a,b,c) \
  73         a[0]=b[0]-c[0]; \
  74         a[1]=b[1]-c[1]; \
  75         a[2]=b[2]-c[2];
  76
  77 #define SCALE(a,k) \
  78         a[0]*=k; \
  79         a[1]*=k; \
  80         a[2]*=k;
  81
  82 #define SCALE2(a,b,k) \
  83         a[0]=b[0]*k; \
  84         a[1]=b[1]*k; \
  85         a[2]=b[2]*k;
  86
  87 #define LEN(a) \
  88         sqrt(DOT(a,a))
  89
  90 #define SET(a,x,y,z) \
  91         a[0]=x; \
  92         a[1]=y; \
  93         a[2]=z;
  94
  95 #if 1
  96 #define NORM(a) { \
  97         float invlen = 1/LEN(a); \
  98         SCALE(a,invlen); }
  99 #else
 100 #define NORM(a) { \
 101         float x = DOT(a,a);
 102         float xhalf = 0.5f*x;
 103         int i = *(int*)&x;        // get bits for floating value
 104         i = 0x5f3759df - (i>>1);  // gives initial guess y0
 105         x = *(float*)&i;          // convert bits back to float
 106         x = x*(1.5f-xhalf*x*x);   // Newton step, repeating increases accuracy
 107         SCALE(a,x); }
 108 #endif
 109
 110 #endif
 111
 112 // vim600:fdm=syntax:fdn=1: