Sample Worlds Torn Apart - Water Editor

Start with the simplest stuff and take a look at the Ocean editor.

There's nothing too dramatic here; just note that the sea level value is 7157 meters (and a fraction) above the "surface" of the planet. The decimals are just because the height was adjusted with the thumbwheel. Type in something a little cleaner if you want. The increments of motion of the wheel (the "clicks") are fairly high, but they are based on the current value. Bigger numbers make for bigger increments. When the value is close to zero, the changes are much smaller.

There is also a water material listed. Clicking on the 'm' pops up the material editor. We only have one material here. The values are all constants with one exception - displacement, which is a texture. This provides waves. (Displacements are commonly called "bumps" or "bump maps").

In the control stack, the constant values have, for the most part, a half-circle to the left of the node. This indicates the parameters are potentially represented by functions or textures, not just constants (or "widgets"). If you click on the half-circle, you can change the generation mode for that parameter.

 
 

A "murkiness" value of 1 is pretty close to distilled ocean water. The three numeric values for water and murk absorbtion refer to how much of each color (RGB) are absorbed. Notice that the "blue" absorbtion value for water is much less than the other two, which indicates that blue light is not absorbed much, green is sort of, and red much more. Thus viewing things through the water should give them a blue tint, which makes sense. You should be able to see the bottom features pretty clearly in shallow water.

The displacement (water surface) is not a constant value, but is controlled by a texture, which will produce some wave action. Click on the "t" to bring up the texture editor and examine this.

 
 

The Texture Editor shows a single displacement texture. Clicking on the texture gets a standard kickstand. Reading from the bottom up (the order in which they're used), we find:

  • World coordinates as the initial seed

  • No distortion (for speed and simplicity)

  • Monofractal based

  • An output curve

The monofractal providing the waves has a handful of parameters. The key ones to look at are:

  • Largest feature set to 100 meters (basically the wave frequency, or the distance between wave tops)

  • Result scale of 6 (the amplitude), giving approximately 6 meter waves.

Note that fractal functions are stated to have a range of -1 to +1. This does not mean, however, that their values are limited to this range exclusively. Consider this to be a "normal" set of values. The only way to really get an idea what the fractal function will produce is to use the small grayscale displays in the texture editor, which, for the terrain editor, also provide minimum and maximum values. For the water textures you just have to do a quick render and see what you've got.

The output control provides a basic curve editor. In this case, everything is set at the defaults: a linear diagonal graph with input values (ranging from 0 to 1) matching output values (also ranging from 0 to 1). If you look at any point on the curve, the input value (the X axis value) is the same as the output (the Y axis value). This is a do-nothing curve and will not affect the output of the wave-height fractal.

To increase the size of the waves to 24 meter monsters, there are two easy methods: change the monofractal scale from 6 to 24, or use the curve editor to quadruple the output. Do this by changing the curve output range from 0 to 4. This means that input values from 0 to 1 are mapped linearly to the given range of output values, thus quadrupling them. Since the curve is marked as "Beyond Input: continue" and "Beyond Output: no change" the effect is extended infinitely in either direction unchanged.

The wave quadrupler input curve.

I've taken a bit of liberty with Chris' images here and combined the 'Wave6' and 'Wave24' shots into one - the waves on the left are the original amplitude 6, and the waves on the right are after using his wave quadrupler input curve. Both were rendered at a camera height of about 50 meters.

Part One sections:

Part Two sections:

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