1Intensity Fields
2================
3An intensity field is a colour pattern with the colours abstracted away,
4leaving only a pattern of intensity values, which are numbers between 0 and 1.
5Intensity fields can be animated.
6
7Mathematically, an intensity field is a function
8that maps [x,y,z,t] onto an intensity,
9where [x,y,z] is a point in space, and t is time.
10
11An intensity field can be composed with a colour map
12to construct a texture.
13
14Operations
15----------
16This interface is still experimental.
17
18``show_ifield ifield``
19  Display an intensity field in the graphics window.
20
21``i_linear d``
22  This 2D ifield is a series of vertical stripes of width ``d``;
23  each stripe is a gradient going from 0 to 1 along the X axis.
24
25``i_radial n``
26  This 2D ifield is a radial starburst pattern containing ``n`` pie-slice
27  shaped gradients that go from 0 to 1 along arcs that are a constant distant
28  from the origin.
29
30``i_concentric d``
31  This 2D ifield contains concentric rings of thickness ``d``.
32  Each ring is a gradient from 0 to 1 as the distance increases from the origin.
33
34``i_gyroid``
35  This 3D ifield is constructed from the distance field of the gyroid.
36  The value is 0.5 on the gyroid surface, and reaches 0 or 1 at the extrema,
37  which are points at maximum distance from the gyroid surface.
38
39``i_animate t ifield``
40  Animate an ifield by cycling the values with a period of ``t`` seconds.
41
42Future Work
43-----------
44* Constructors, that build intensity fields.
45* Transformations, that map one ifield onto another.
46* Combinators, that combine two or more ifields, creating a new ifield.
47* Fractal noise, used to create natural looking textures like wood and marble.
48