vec3d.c

来自「嵌入式GUI OpenGL源代码。OpenGL是嵌入式开发中常用的一种GUI系统」· C语言 代码 · 共 74 行

/* Copyright (c) Mark J. Kilgard, 1997. */

/* This program is freely distributable without licensing fees 
   and is provided without guarantee or warrantee expressed or 
   implied. This program is -not- in the public domain. */

/* Simple 3D vector routines.  This file is meant to be included in
   a .c file, hence all the routines are defined statically.  A
   good C compiler should be able to automatically inline all
   these routines. */

#include <math.h>

static void
vnorm(float vec[3])
{
  float len;

  len = (float)sqrt(vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2]);
  vec[0] = vec[0] / len;
  vec[1] = vec[1] / len;
  vec[2] = vec[2] / len;
}

static float
vdot(float a[3], float b[3])
{
  return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
}

static void
vdiff(float dst[3], float a[3], float b[3])
{
  dst[0] = a[0] - b[0];
  dst[1] = a[1] - b[1];
  dst[2] = a[2] - b[2];
}

static void
vadd(float dst[3], float a[3], float b[3])
{
  dst[0] = a[0] + b[0];
  dst[1] = a[1] + b[1];
  dst[2] = a[2] + b[2];
}

static void
vcopy(float dst[3], float src[3])
{
  dst[0] = src[0];
  dst[1] = src[1];
  dst[2] = src[2];
}

static void
vscale(float dst[3], float src[3], float scale)
{
  dst[0] = src[0] * scale;
  dst[1] = src[1] * scale;
  dst[2] = src[2] * scale;
}

static void
vcross(float cross[3], const float v1[3], const float v2[3])
{
  float tmp[3];

  tmp[0] = (v1[1] * v2[2]) - (v1[2] * v2[1]);
  tmp[1] = (v1[2] * v2[0]) - (v1[0] * v2[2]);
  tmp[2] = (v1[0] * v2[1]) - (v1[1] * v2[0]);
  vcopy(cross, tmp);
}