Examples

Example 1 Example 2 Example 3 Example 4

Documentation

Formulas are defined using "Reverse Polish Notation." Here are the different operations it supports:

• r the current radius between 0 and 1
• t the current time. elements at a single radius have a time offset
• n negate the previous value
• m absolute value of the previous value
• + add the previous two values
• * multiply the previous two values
• - subtract the previous value from the one before it
• / divide the previous value from the one before it
• & bitwise-and the previous two values
• | bitwise-or the previous two values
• ^ bitwise-xor the previous two values
• d duplicate the previous value
• s take the sine of the previous value
• c take the cosine of the previous value
• e Raise the second-to-last value to the last value
• P Pi

Example

tcr* tsr*
At t=0, r=1

The formula is evaluated character-by-character

1. t Push the current time onto the stack. The stack is now [0]
2. c Take the top of the stack off the stack and push its cosine onto the stack. The stack is now [1]
3. r Push the current radius onto the stack. The stack is now [1 1]
4. r Pop the top two values of the stack and push their product onto the stack. The stack is now [1]
5. t Push the current time onto the stack. The stack is now [1 0]
6. s Take the top of the stack off the stack and push its sine onto the stack. The stack is now [1 0]
7. r Push the current radius onto the stack. The stack is now [1 0 1]
8. r Pop the top two values of the stack and push their product onto the stack. The stack is now [1 0]

Now that we have gone through every character, the circle is drawn at the point specified by the top two values x=1, y=0