Description:

This surface generates layers of pebbles using bombing techniques. It also does some fake shadows and shading. An image can be used to control the distribution of the pebbles. The greyscale value of the image determines how many layers to place in a particular region of the image.

 * ---- common parameters -------------
 * layers: Number of layers of pebbles. Higher numbers will slow rendering
 * scale: Zoom out of the image - higher values makes rocks smaller
 * seed: Controls random characteristics
 * distimg: Image controlling distribution of pebbles. White areas will
 *          cause "layers" layers to be drawn. No layers will be drawn
 *          in black areas, and the number of layers will vary according
 *          to the values in between.
 *
 * ---- surface parameters ----------
 * shdw: Creates shadows - preferred values between [0,1]
 * shading: Shades the sides of the pebbles. The value is used as follows:
 *           0 - turn off shading
 *           >0 - turn on shading and multiply color by the parameter value
 * minc, maxc: Range of pebble colors in HSV
 *
 * ---- displacement parameters ----------
 * depthshade: modify the height of the pebble by the layer. This causes the
 *   smaller pebbles in the lower layers to have a smaller displacement.
 * Km: A constant amount to scale the displacement by.

    

Layers and Shadow

distimg

layers = 15 seed = 4 shadow = 0	layers = 15 seed = 4 shadow = 0.5	layers = 15 seed = 4 shadow = 1
layers = 20 seed = 4 shadow = 0.75	layers = 5 seed = 4 shadow = 0.75	layers = 15 seed = 42 shadow = 0.75