Tutorial: Advanced Textures in POV-Ray
To start modeling in POV-ray it is always useful to make some preliminary
preparations and organize your environment. It is known from POV
documentation that "in general, the more memory you have (up to a point) the
faster things will run". Probably this statement is not referring to machines
with 1G RAM, but for older computers with 250 Mb memory you can achieve this
by installing some flavor of Linux operating system with a lightweight
desktop like XFCE. In Linux POV-Ray is a command line tool. This means that
it has no GUI at all. For a Windows user the idea of using a program without
an interface might seem absurd, but this approach provides some benefits. You
can use a more powerful editor than the one built in POV-Ray for Windows.
Emacs has a decent POV-mode. Another popular editor written in Java and
suitable for POV-Ray is jEdit. I use it both in Linux and Windows. The pieces
of POV code you will find below were made by jEdit plugin Code2HTML.
It is not very convenient to use an external editor to edit POV scene
files in Windows but is possible. The way is the same as for Linux. You need
to make an ini file that contains all the necessary commands like this one generated by povanim in Blender. Take a look also
at this tutorial
explaining the meaning of every key. In Linux you will need to enter a
command pointing to this file in an X-terminal, while in Windows you can do
it the following way: Open your ini file in the POV editor and run once.
After rendering close it together with all other tabs. POV-Ray will remember
the last edited file and will render it every time even if it is closed. Now
you can edit your scene in your favorite editor and start rendering by
pressing hot-keys combination ALT-G after clicking on the POV window
to activate. The error messages will be displayed in the POV-Ray console.
I won't repeat what is said already and describe the POV syntax. All that
is very well documented, and you will find tons of syntax examples here. I will say only that it is
always a good idea to use some kind of a texture editor to rough in your
texture, which can be finely tuned later manually in your favorite editor. On
my Debian partition I used Truevision, 3D modeler for Gnome, converted from
rpm with alien. Truevision was nice but crashed too often to be called usable, and I wrote my own texture editor TexGenPOV. Give it a try.
No matter how simple or complex textures are, each following texture if
applied occupies the whole volume and lays on top of the previous one. Let's
take a look at the examples.
This is just a simple texture with a color map.
1:#declare C_Map = color_map {
2: [ 0.0 rgbft<1,0,0,0,0> ]
3: [ 0.4 rgbft<1,1,0,0,0> ]
4: [ 0.6 rgbft<1,1,0,0,0> ]
5: [ 1.0 rgbft<0,0,1,0,0> ]
6: }
7:
8:
9:#declare Plain =
10:
11: texture {
12: pigment {
13: wood
14: color_map {C_Map}
15: translate <0,0,0> scale <0.1,0.1,0.1> rotate <0,0,0>
16: }
17: }
18:
19:
20:
21:box {
22: <1,1,-1>,
23: <-1,-1,1>
24: texture {Plain}
25:
26:}
But if we apply a list texture, checker in this case, with the same
parameters for each texture, we will get the same result.
1:#declare Checker =
2: texture {checker
3: texture {
4: pigment {
5: wood
6: color_map {C_Map}
7: translate <0,0,0> scale <0.1,0.1,0.1> rotate <0,0,0>
8: }
9: }
10:
11: texture {
12: pigment {
13: wood
14: color_map {C_Map}
15: translate <0,0,0> scale <0.1,0.1,0.1> rotate <0,0,0>
16: }
17: }
18:
19:}
20:
21:
22:box {
23: <1,1,-1>,
24: <-1,-1,1>
25: texture {Checker}
26:}
As we see, each time a texture occupies the whole volume and in checker
the second texture is not noticeable until we change something in it.
1:#declare Checker =
2: texture {checker
3: texture {
4: pigment {
5: wood
6: color_map {C_Map}
7: translate <0,0,0> scale <0.1,0.1,0.1> rotate <0,0,0>
8: }
9: }
10:
11: texture {
12: pigment {
13: wood
14: color_map {C_Map}
15: translate <0,0,0> scale 0.3 rotate <0,0,0>
16: }
17: }
18:
19:}
20:
21:
22:box {
23: <1,1,-1>,
24: <-1,-1,1>
25: texture {Checker}
26:
27:}
But herein lies a problem. What if we want to apply more than one
patterned texture? We will get the error: "Parse Error: Cannot layer
over a patterned texture". Like on this example:
1:#declare Checker1 = texture {checker
2: texture {
3: pigment {
4: wood
5: color_map {C_Map}
6: translate <0,0,0> scale <0.1,0.1,0.1> rotate <0,0,0>
7: }
8: }
9:
10: texture {
11: pigment {
12: wood
13: color_map {C_Map}
14: translate <0,0,0> scale 0.3 rotate <0,0,0>
15: }
16: }
17:}
18:
19:
20:#declare Checker2 =texture {checker
21: texture {
22: pigment { rgbf <1,0,1,1> }
23: }
24:
25: texture {
26: pigment { rgbf <1,0,1,1> }
27: }
28:}
29:
30:
31:#declare Patterned = texture {Checker1}
32: texture {Checker2}
To fix this error we need to redeclare everything as pigment:
1:#declare Checker1 = pigment {checker
2: pigment {
3: wood
4: color_map {C_Map}
5: translate <0,0,0> scale 0.1 rotate <0,0,0>
6: }
7:
8: pigment {
9: wood
10: color_map {C_Map}
11: translate <0,0,0> scale 0.3 rotate <0,0,0>
12: }
13: }
14:
15:
16:
17:#declare Checker2 = pigment {checker
18: pigment { rgbf <1,0,1,1> }
19: pigment { rgbf <0,1,1,1> }
20: }
21:
22:#declare Patterned = texture {Checker1}
23: texture {Checker2}
That's all. Now I am going to tell you how I made Malachite.
I have never seen Malachite in reality only on pictures. I took a high
resolution image of this mineral and cut a stripe out of it in Gimp. Then
using an onscreen pixel ruler and a color picker I made a color map. The
illustration is on the top of this page and here. The trickiest part of creating
the texture was to find the values for frequency, turbulence, octaves, lambda
and omega that resemble the original stone pattern. Then when everything was
ready, I extruded the texture along the z-axis with warp planar,
because malachite in nature is made of cylinders of mineral
stratification.
POV texture Malachite
|
Malachite Stone
|
Malachite Mineral
|
The POV code
of the Malachite texture is here.
