They are discussed more fully later in this section. You can select random input to any contiguous span of bits in each cell. On every generation these bits will be set to a new random value. Selecting random bits slows the execution of the simulator somewhat. To create position sensitive rules, you can specify that a vertical or horizontal texture be placed in the state map as input to the rule definition.
Horizontal texture identifies the individual cells along rows in the state map.
To enable horizontal texture set texthb to the number of the least significant bit of the field which contains the horizontal texture and texthn to the number of horizontal texture bits desired. If you select more than one bit of texture, the value increments within the field size you specify. If you set texthb and textvb to the same bit and texthn and textvn to 1, a checkerboard pattern will be generated. It's up to the rule to preserve the texture from generation to generation by returning the texture bits as they were specified by oldstate . You can request that a specific pattern file be loaded when a rule is loaded by setting the patreq variable to the pattern file name using the strcpy function.