draft
If you are trying to use OpenGL from C, you might want a vector and matrix math package so you dont have to write your own. Here is one that looks pretty good to me.
And the internet being the way it is, I include the source code here:
/****************************************************************************/
/* VECTMATH.H: include file for vector/matrix operations. */
/* Copyright (c) 1999 by Joshua E. Barnes, Tokyo, JAPAN. */
/****************************************************************************/
#ifndef _vectmath_h
#define _vectmath_h
#include "vectdefs.h"
/*
* Vector operations.
*/
#define CLRV(v) /* CLeaR Vector */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = 0.0; \
}
#define UNITV(v,j) /* UNIT Vector */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = (_i == (j) ? 1.0 : 0.0); \
}
#define SETV(v,u) /* SET Vector */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = (u)[_i]; \
}
#if defined(THREEDIM)
#define ADDV(v,u,w) /* ADD Vector */ \
{ \
(v)[0] = (u)[0] + (w)[0]; \
(v)[1] = (u)[1] + (w)[1]; \
(v)[2] = (u)[2] + (w)[2]; \
}
#define SUBV(v,u,w) /* SUBtract Vector */ \
{ \
(v)[0] = (u)[0] - (w)[0]; \
(v)[1] = (u)[1] - (w)[1]; \
(v)[2] = (u)[2] - (w)[2]; \
}
#define MULVS(v,u,s) /* MULtiply Vector by Scalar */ \
{ \
(v)[0] = (u)[0] * s; \
(v)[1] = (u)[1] * s; \
(v)[2] = (u)[2] * s; \
}
#else
#define ADDV(v,u,w) /* ADD Vector */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = (u)[_i] + (w)[_i]; \
}
#define SUBV(v,u,w) /* SUBtract Vector */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = (u)[_i] - (w)[_i]; \
}
#define MULVS(v,u,s) /* MULtiply Vector by Scalar */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = (u)[_i] * (s); \
}
#endif
#define DIVVS(v,u,s) /* DIVide Vector by Scalar */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = (u)[_i] / (s); \
}
#if defined(THREEDIM)
#define DOTVP(s,v,u) /* DOT Vector Product */ \
{ \
(s) = (v)[0]*(u)[0] + (v)[1]*(u)[1] + (v)[2]*(u)[2]; \
}
#else
#define DOTVP(s,v,u) /* DOT Vector Product */ \
{ \
int _i; \
(s) = 0.0; \
for (_i = 0; _i < NDIM; _i++) \
(s) += (v)[_i] * (u)[_i]; \
}
#endif
#define ABSV(s,v) /* ABSolute value of a Vector */ \
{ \
real _tmp; \
int _i; \
_tmp = 0.0; \
for (_i = 0; _i < NDIM; _i++) \
_tmp += (v)[_i] * (v)[_i]; \
(s) = rsqrt(_tmp); \
}
#define DISTV(s,u,v) /* DISTance between Vectors */ \
{ \
real _tmp; \
int _i; \
_tmp = 0.0; \
for (_i = 0; _i < NDIM; _i++) \
_tmp += ((u)[_i]-(v)[_i]) * ((u)[_i]-(v)[_i]); \
(s) = rsqrt(_tmp); \
}
#if defined(TWODIM)
#define CROSSVP(s,v,u) /* CROSS Vector Product */ \
{ \
(s) = (v)[0]*(u)[1] - (v)[1]*(u)[0]; \
}
#endif
#if defined(THREEDIM)
#define CROSSVP(v,u,w) /* CROSS Vector Product */ \
{ \
(v)[0] = (u)[1]*(w)[2] - (u)[2]*(w)[1]; \
(v)[1] = (u)[2]*(w)[0] - (u)[0]*(w)[2]; \
(v)[2] = (u)[0]*(w)[1] - (u)[1]*(w)[0]; \
}
#endif
/*
* Matrix operations.
*/
#define CLRM(p) /* CLeaR Matrix */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = 0.0; \
}
#define SETMI(p) /* SET Matrix to Identity */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (_i == _j ? 1.0 : 0.0); \
}
#define SETM(p,q) /* SET Matrix */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (q)[_i][_j]; \
}
#define TRANM(p,q) /* TRANspose Matrix */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (q)[_j][_i]; \
}
#define ADDM(p,q,r) /* ADD Matrix */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (q)[_i][_j] + (r)[_i][_j]; \
}
#define SUBM(p,q,r) /* SUBtract Matrix */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (q)[_i][_j] - (r)[_i][_j]; \
}
#define MULM(p,q,r) /* Multiply Matrix */ \
{ \
int _i, _j, _k; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) { \
(p)[_i][_j] = 0.0; \
for (_k = 0; _k < NDIM; _k++) \
(p)[_i][_j] += (q)[_i][_k] * (r)[_k][_j]; \
} \
}
#define MULMS(p,q,s) /* MULtiply Matrix by Scalar */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (q)[_i][_j] * (s); \
}
#define DIVMS(p,q,s) /* DIVide Matrix by Scalar */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (q)[_i][_j] / (s); \
}
#define MULMV(v,p,u) /* MULtiply Matrix by Vector */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) { \
(v)[_i] = 0.0; \
for (_j = 0; _j < NDIM; _j++) \
(v)[_i] += (p)[_i][_j] * (u)[_j]; \
} \
}
#define OUTVP(p,v,u) /* OUTer Vector Product */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (v)[_i] * (u)[_j]; \
}
#define TRACEM(s,p) /* TRACE of Matrix */ \
{ \
int _i; \
(s) = 0.0; \
for (_i = 0.0; _i < NDIM; _i++) \
(s) += (p)[_i][_i]; \
}
/*
* Enhancements for tree codes.
*/
#if defined(THREEDIM)
#define DOTPSUBV(s,v,u,w) /* SUB Vectors, form DOT Prod */ \
{ \
(v)[0] = (u)[0] - (w)[0]; (s) = (v)[0] * (v)[0]; \
(v)[1] = (u)[1] - (w)[1]; (s) += (v)[1] * (v)[1]; \
(v)[2] = (u)[2] - (w)[2]; (s) += (v)[2] * (v)[2]; \
}
#define DOTPMULMV(s,v,p,u) /* MUL Mat by Vect, form DOT Prod */ \
{ \
DOTVP(v[0], p[0], u); (s) = (v)[0] * (u)[0]; \
DOTVP(v[1], p[1], u); (s) += (v)[1] * (u)[1]; \
DOTVP(v[2], p[2], u); (s) += (v)[2] * (u)[2]; \
}
#define ADDMULVS(v,u,s) /* MUL Vect by Scalar, ADD to vect */ \
{ \
(v)[0] += (u)[0] * (s); \
(v)[1] += (u)[1] * (s); \
(v)[2] += (u)[2] * (s); \
}
#define ADDMULVS2(v,u,s,w,r) /* 2 times MUL V by S, ADD to vect */ \
{ \
(v)[0] += (u)[0] * (s) + (w)[0] * (r); \
(v)[1] += (u)[1] * (s) + (w)[1] * (r); \
(v)[2] += (u)[2] * (s) + (w)[2] * (r); \
}
#endif
/*
* Misc. impure operations.
*/
#define SETVS(v,s) /* SET Vector to Scalar */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = (s); \
}
#define ADDVS(v,u,s) /* ADD Vector and Scalar */ \
{ \
int _i; \
for (_i = 0; _i < NDIM; _i++) \
(v)[_i] = (u)[_i] + (s); \
}
#define SETMS(p,s) /* SET Matrix to Scalar */ \
{ \
int _i, _j; \
for (_i = 0; _i < NDIM; _i++) \
for (_j = 0; _j < NDIM; _j++) \
(p)[_i][_j] = (s); \
}
#endif /* ! _vectmath_h */
Micheal
ReplyDeleteIt's so cool that you can write about the reality (and non-reality) of national politics, recent histories of CGI and Los Angeles, then chat about visual projects and coding. All connected by the thread of empirical reality. Thanks for all the work keeping your blog going.
Dennis