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diff --git a/docs/Behaviors/Behaviors.tex b/docs/Behaviors/Behaviors.tex new file mode 100644 index 0000000..5105588 --- /dev/null +++ b/docs/Behaviors/Behaviors.tex @@ -0,0 +1,155 @@ +\documentclass{article} +\usepackage{fullpage} +\usepackage{graphicx} +\begin{document} + \title{Behaviors: An Introduction and Exercises} + \author{Russell Cohen} + \date{\today} + \maketitle + \section{What is a behavior?} + At its most basic, a behavior is machine with two input terminals and two + output terminals. One of these input terminals is external input. The + other is feedback from the behavior. Similarly, the behavior has two output + terminals. One gets released externally as output, and the other gets fed + back to the behavior. At their core, behaviors have nothing to do with + pixels are light effects -- this is merely how we commonly use them. + \begin{center} + \includegraphics[width=4 in]{Behavior.jpg} + \end{center} + \section{How do I write a behavior?} + At the core of a behavior is its \texttt{ProcessResponse} method which + tells a behavior what to get on input. As you might expect, it has 2 + input ports, and two output ports. The `type' of inputs and outputs can be + anything -- numbers, strings, lists, however, in our system, the inputs + and outputs are all python dictionaries. This allows us to have an + arbitrary number of named parameters. As sample input might look + something like \texttt{{'Location':(20,20), 'Height':10}}. When we + return a value, we return a tuple of \texttt{(list<dict>,list<dict>)}. Note that on a + process response method you will actually be given a \textbf{List of + dictionaries} and you should iterate over them. + \textbf{Important:} You should not directly modify the inputs! Use + \texttt{dict(input)} to create a copy of them! + \section{Exercise 1: addFive} + Our goal: Create a behavior that will add 5 to the 'Value' field of the + input. If no 'Value' field exists, we will set it to five. Below is a + sample \verb processResponse method to do this. Note that process + response is the only part of a behavior that must be written (everything + else happens behind the scenes when you \textbf{inherit} from the + \texttt{Behavior} class. + \begin{verbatim} + def processResponse(self, inputs, recurrences): + output = [] #empty list + for inp in inputs: + inpCopy = dict(inp) + if not ('Value' in inpCopy): + inpCopy['Value'] = 0 + inpCopy['Value'] += 5 + output.append(inpCopy) + return (output, []) #empty list, no recurrences + \end{verbatim} + \section{Exercise 2: A Sum-er} + Create a behavior that outputs the sum of all previous input. Hint: + You will need to use recurrences! + \section{Declaring and Configuring Behaviors} + Once you've written your behavior (or are using an already written + behavior, you will need to tell the light installation to use the + behavior. This is done via XML in the configuration file. When you + run the system, you specify a configuration file eg: + \texttt{python LightInstallation.py config/ConfigFile.xml} + + Behaviors are specified in the \verb BehaviorConfiguration section. + A sample behavior follows: + \begin{verbatim} + <Behavior> + <Class>behaviors.EchoBehavior</Class> + <Args> + <Id>echo</Id> + <RenderToScreen>False</RenderToScreen> + </Args> + </Behavior> + \end{verbatim} + + The ``Class'' attribute specifies the \textbf{Python} class for this + behavior. (The \verb behaviors. prefix tells Python to look in the + behaviors folder). You may recall that all classes SmootLight take a + single python dictionary as an argument -- this is embodied by the + \texttt{Args} tag. A dictionary is created from the XML at runtime + -- this dictionary would be: \texttt{{'Id':'echo', + 'RenderToScreen':False}} + The id we specify is the id that we can reference this behavior by + later. The \verb RenderToScreen attribute specifies whether or not + outputs from this behavior should be directed to the screen (some + behaviors act only as the building blocks for other + behaviors, and are never rendered directly to the screen) + + \section{Behavior Chains} + I have mentioned several times that the system allows for behaviors to + be chained together to create many different effects -- often the + ``motion'' effect and the ``coloring'' effects are two separate + behaviors. The result you see on the screen are these two pieces + connected together. This allows us to build up many different behaviors + from a library of simple pieces. Let's look at how we actually + accomplish this. + + Behavior Chaining is accomplished through the behavior chain class. + Here is an example of a behavior we declare (in XML) via a behavior + chain: + \begin{verbatim} + <Behavior> + <Class>behaviors.BehaviorChain</Class> + <Args> + <Id>runcolordecay</Id> + <Inputs> + <Id>pygame</Id> + <Id>randomLoc</Id> + </Inputs> + <ChainedBehaviors> + <Id>colorchange</Id> + <Id>running</Id> + <Id>decay</Id> + </ChainedBehaviors> + <RecursiveHooks>{'running':'acceleratedie'}</RecursiveHooks> + <RenderToScreen>True</RenderToScreen> + <Mapper>gaussmap</Mapper> + </Args> + </Behavior> + \end{verbatim} + + Note the importance of the `Id' field -- that is how we reference all + other components of the system. Let's walk through what is going on + here. We declare this behavior just like any other -- however, for + class, we specify \verb BehaviorChain . The \verb Inputs tag specifies + which inputs will be routed to this behavior. In this case, it is + \verb pygame and \verb randomLoc , two previously declared behaviors. + Inputs from these behaviors will be passed to the behavior chain via + sensorInputs. Next, we have the meet of this chain, the behaviors it is + composed of. This states that first, an input is routed through + \texttt{colorchange}. \verb colorchange adds a color field to the + sensor data. Next, the input is routed to \verb running a behavior + that makes pixels run back and forth. Finally, the input is routed to + \verb decay , a behavior that adds a decay ``PixelEvent'' that makes + individual pixels turn on and then decay. + + The next item we see is \verb RecursiveHooks . This is a special + feature of the \verb BehaviorChain that allows us to augment the + reccurences recursive events have. We specify that we will augment the + recursive behavior of \verb running with another behavior, + \verb acceleratedie which modifies increases the speed of the running + behavior, and stops the behavior after a certain number of iterations. + Note that recursive hooks take data in via their \textbf{external input} + port, and \textbf{not} their recursive port. + \begin{center} + \includegraphics[width=4 in]{BehaviorwithRecursiveHook.jpg} + \end{center} + Finally, we state that this behavior will indeed be rendered directly to + the screen, by specifying: + \begin{center}\texttt{<RenderToScreen>True</RenderToScreen>} \end{center} + We also specify which PixelMapper we want to use (gaussmap): + \texttt{<Mapper>gaussmap</Map>}. \verb gaussmap is the id we assigned to the mapper when + we declared in the \verb PixelMappers section of the xml. + \begin{center} + Phew. This isn't as complicated as it sounds. I promise. + \end{center} + Browse around the behaviors to get an idea of what is possible and what has been done. They + all live in the behaviors folder. Enjoy! + \end{document} |