cs320n – elements of visual programming

CS320n – Elements of Visual Programming

Alice ConceptsMike Scott(Slides 1-2)

Visual Programming Alice Concepts 2

What We Will Do Today• Finish the material in chapter 1• Continue working on the tutorials and

appendix 1 material in Alice


Types of Animation• Two kinds of Alice animations

– Movie• User “watches” animation• “machine-centric”

– Interactive• User participates – clicks mouse,

controls actions with keys• “user centric”


Events• Animations that are “interactive depend on the

user’s actions– mouse click– key press– others (head mounted device, dance pad)

• Actions are events• Interactive programs are event driven

Event window portion of Alice


Interactivity in Alice• Animation with no

interaction– Movie– DEMO Octopus Ride

• Animation with interaction– DEMO Ice Skater– What are the events?– What response does the

skater make to each event?


Objects• What is an object?

– anything that can uniquely identified from other things

• What makes an object unique?– has a name– has properties

• width, height, color, location, age, id#– has a purpose

• associated actions it can perform• tasks it can carry out – things it knows how to do


Classes• Objects are categorized into classes

• Each objects is an instance of the class• All objects in a class

– have the same properties– generally can perform the same tasks

Penguins

Dogs

Skipper

Kowalski

PrivateSnoopy

Odie

RenOpus

Rico


Objects in a Virtual World• In Alice, each 3D model is a class of

objects– class: penguin– objects: penguin,

penguin1, penguin2


Changing Properties of Obejcts• Properties of Object can be

changed• Location can be changed by

clicking and moving object• Orientation can be changed

in the “Add Objects” View• Other properties, such as

color, can be changed in the properties window when the object is selected


Object Parts• Objects may be composed of parts

– which may in turn be composed of parts– the whole object may be told to do something or

an individual part


Center of an Object• each object has center point

– usually near center of mass, but really set by graphic artist that created object

– spin point for object– things that sit or stand on

ground usually havecenter between feet

– things that are held havecenter at point object would be held


Distance• object’s distance from each other are

based on the distance between their center points

• may look like objects are zero distance away, but actually centers still some positive distance away


Position in the World• The world in an Alice

program models a 3D space

• every object in the world has a positionx, y, z, coordinate relative to the center of the world

• ground starts at center of world

• axes (green = up, red = right, blue = forward)


Adding 3D Text• Under the “Add Objects”

window• Creates a 3D Text Object that

can be positioned in the scene• Like other objects it has a host

of behaviors and properties


Adding “Billboards”• Billboards are flat, 2D

images in a scene• Almost any graphic type

can be added.• GIF, JPG, TIF, PNG, BMP• Select file and image is

added to scene• Images must be created is

some other program


Class Work• Continue work on tutorials• Appendix A,

– Part 1 – Part 2: Using Pop up menus to create an

initial scene.

cs320n – elements of visual programming

Documents

point object

d spaceevery object

d text object

objecteach object

object unique

center pointsmay

center of mass

alice program