blob: 83e27c608e4b1bf43911e602d1e98482a2f51e6f (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
"http://www.w3.org/TR/REC-html40/loose.dtd">
<!-- $Id: vec3.html 86 2000-06-13 18:59:13Z garland $ -->
<html>
<head>
<title>libgfx: Vector Math</title>
<link rel=stylesheet href="cdoc.css" type="text/css">
<meta name="Author" content="Michael Garland">
</head>
<body>
<h2>Vector Math</h2>
<h3>class Vec3</h3>
<p> This class implements a 3-dimensional real-valued vector.
Individual elements are represent with <code>double</code> precision
floating point numbers. To use the <tt>Vec3</tt> class you must
include the header
<pre>
#include <gfx/vec3.h>
</pre>
<h4>Constructor Methods</h4>
<p>The <tt>Vec3</tt> class defines the following set of constructors:
<pre>
Vec3(); <i>// Initializes vector to (0 0 0).</i>
Vec3(double x, double y, double z); <i>// Initializes vector to (x y z).</i>
Vec3(double s); <i>// Initializes vector to (s s s)</i>
Vec3(const Vec3& v); <i>// </i>
Vec3(const float v[3]); <i>// These copy values from v</i>
Vec3(const double v[3]); <i>// </i>
Vec3(const Vec2& v, double z); <i>// Initializes vector to (v[0] v[1] z)</i>
</pre>
<h4>Specialized Functions</h4>
<p>In addition to the standard functions provided by all vector classes,
the <tt>Vec3</tt> class defines certain specialized functions which
operate only on 3-D vectors.
<p>The <em>cross product</em> of two vectors <tt>v, w</tt> is a third
vector which is perpendicular to both <tt>v</tt> and <tt>w</tt>.
It can be computed with either a function call or an overloaded
operator
<pre>
u = cross(v, w); <i>// Equivalent ways of computing</i>
u = v ^ w; <i>// the cross product of v and w.</i>
</pre>
<p>Since 3-D vectors may be used to represent 2-D homogeneous
coordinates, a projection function is provided.
<pre>
Vec2 proj(const Vec3& v);
</pre>
This routine takes a homogeneous vector <i>(x y w)</i> and returns the
corresponding 2-D vector <i>(x/w y/w)</i>. If <i>w</i> is 0 then
the vector <i>(x y)</i> is returned.
</body>
</html>
|
