Another kind of iteration you often want to do when constructing programs, is to count things. Quartz composer provides the counter patch, which increments a running total when one of it's inputs switches from false to true. Similarly, it decrements the total whenever the signal to it's other input changes from false to true.
By generating a regular true/false alternating value, and connecting this up to the increment line, you could generate a regular count. This composition demonstrates one way to do this. Using the Patch Time patch, a count of time in seconds is passed through a modulo 2 operator to generate a regular sequence of alternate 1s and 0s. This is connected up to the increment line of the counter, which then counts upward in integers.
The counter value is used to govern the stripe width of a vertical stripe pattern. As the patch runs, the stripe width increases every other second. This is a very simple display, but the bit generator and accumulator demonstrated are useful in a variety of ways. You can download a copy of this patch here.
This entry was posted on Sunday, February 10, 2008 at 13:25 in computers, programming.
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