Most of these natural looking textures make use of a fractal turbulence function (TURB), which works by summing a random noise function (NOISE) at different frequencies and scales.
Pixel Magic contains both 2d and 3d versions of these functions. The 3D versions are useful for creating animated turbulence effects, such as moving clouds.
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Clouds | In this picture, the saturation function uses the turbulence function (TURB) to provide a cloud-like desaturation of the skyblue field provided by the hue function. The brightness value is also raised, using the same function. |
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Lightning | This is basically an inverted marble. |
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Marble | Passing the absolute value of TURB (which normally returns values in the range -1 thru 1) to SQRT causes sharp black "veins" to appear, which have the appearence of marble. |
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Planet Clouds | The sx() and sy() functions can be used to create textures which map onto spheres. These can be used as texture maps for 3D rendering programs. This particular texture maps the turbulence function onto a sphere, creating a cloud enshrouded planet. |
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Tree Trunk | In this image a pattern of concentric rings is perturbed using the turbulence function, creating a wood-like pattern. |
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Water |
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Waves | In this example, a cosine function is perturbed by a 3-D fractal turbulence function. The time variable produces a movie showing the wave in motion. This can be used for a bump map to produce a natural wave-like texture. |