cs320n – elements of visual programming

CS320n – Elements of Visual Programming

Introduction to Alice

Mike Scott

(Slides 1-1)

Visual Programming Introduction to Alice 2

What We Will Do Today• look at the Alice programming

environment

• create some simple programs in Alice


What is Alice?• Named in honor of Lewis Carroll’s (pen

name) Alice in Wonderland– Charles Lutwidge Dodgson was also a

mathematician and logician• A modern programming tool

– purpose of tool, learn how to program, write algorithms

– 3-D graphics– 3-D models of objects

• Animation– Objects can be made to move around virtual

world (a simulation or a video game. Simple Pixar.)


Computer Programs• General purpose programming languages

can be used for almost any task

• Alice is not a general purpose programming language. – It is an application specific language– designed for a specific task, creating 3D

animations– lots of application specific languages.

Example: language for working with DNA data


Fundamental Tools• All languages contain these elements

1. list of instructions – “Pack lunch, pack snack, put homework in backpack.”

2. decision making – “If I didn’t shave yesterday, shave today.”

3. repetition of behavior – “Do a load of laundry until there is no more dirty laundry.”

4. modularization. Big rocks into little rocks. “To do a load of laundry: gather clothes, get clothes right-side out, put clothes of similar color into washing machine…”

5. Generalization: Solve many different problems with one set of instructions

6. Compute a result – “How much is it going to cost to fill up my car with gas?”


What does Alice run on?• Alice is free.

• Alice is written in Java– only working versions are for PCs and Macs

with OSX 10.3 or higher (relatively new, may still have bugs)

– Sorry, no Linux, yet– the book comes with a copy of Alice for

Windows machines– www.alice.org– also on the computers in the CS Elements lab


Fast Start Up • Can quickly learn to create

– a simple animation in a matter of minutes– a non-trivial animation in a few class periods

• Can learn to use the Alice interface in a few class periods if you do a couple of exercises at home


Installing Alice• If you want to install Alice on you computer at home

– use the CD that comes with the textbook• CD installation is straightforward

– download Alice from the web• http://www.alice.org/downloads/authoringtool/• file format is .zip• must “unzip” file using a program such as winzip

• problems? post to newsgroup


Memory Management• Alice automatically manages memory• But, writing and testing an animation is an

intense load on the computing system – a crash can occur.

• Best solution: • Alice (the program) reminds you every so often

so save your work• save your programs often!• if working in lab when you logout the computer is

wiped -> save to your account or to a backup system such as a memory stick


The Power of Alice• Automatically keeps track of 3-D objects

– what objects are in the virtual world– types of objects– positions of objects in the world


Demo• Starting Alice

• Loading a World

• Running A World

• Saving a World

• How to Exit


The World• Alice Programs / Movies take place in a

virtual world

• When you start a new world in Alice you select the background

•The world consistsof a sky and the ground•Can’t be changed aftercreating the world•the world is not infiniteDEMO(I don’t like roller coasters any more)


Objects in Alice• Objects already exist. Hundreds of them


Program an Object


Where Do Objects Come From?• They are pre built

– creating 3D objects is another area of computing and graphic design

• Sources of 3D objects – the local gallery that comes with the software

– Alice web gallery

• How are objects added to the world?


Adding Objects• Click on the green “Add Objects” button

• World expands and local gallery displayed


Adding Objects• Local gallery divided into a directory based

on subject

• add instances of objects to world by – dragging and dropping or – click on object and select add instance option


Objects in the World• Can have multiple instances of objects

from the same class in the World– class: like a cookie cutter– objects: like the cookies

star cookie cutterstar cookie class

star cookiesstar cookie objects


Objects in the World

penguin class penguin objects in a virtual world


Objects in the World• The Objects that are present in the current

world are listed in the Object Tree

• The top left panel in the Alice programming environment

• Every world comes with a light, a camera (point of view for the movie whenplayed), and the ground


Object Dimensions• Objects in Alice worlds are 3 dimensional

height width depth


Object Position

• Objects – are positioned in 3-D space– Have six degrees of freedom (directions of movement)


Objects “Know” Relative Directions• Yellow box around

penguin is itsbounding box

• light blue line isup/down

• pink line is left/right

• dark blue line isforward backward

• DEMO


Exercises

• if you want to work at home, install Alice on your computer

• Complete Appendix A, Part 1, using Alice– a walkthrough of using Alice

• Complete the tutorials that come with Alice


Starting Tutorials

cs320n – elements of visual programming

Documents

copy of alice

straightforwarddownload

alice interface

d objects

simple programs

simple animation

new world

load of laundry