Processing_1_Triangle & Grid
-Controls a sequence of repetitions. A basic for structure has three parts: init, test, and update. Each part must be separated by a semicolon (;). The loop continues until the test evaluates tofalse. When a for structure is executed, the following sequence of events occurs:
1. The init statement is run.
2. The test is evaluated to be true or false.
3. If the test is true, jump to step 4. If the test is false, jump to step 6.
4. Run the statements within the block.
5. Run the update statement and jump to step 2.
6. Exit the loop.-
http://www.processing.org/reference/for.html