CS461561 Virtual Environments: Principles

1
CS461/561Virtual Environments Principles
ApplicationsVirtools Basics

• 1-21-2008
• Prof. Searleman
• SC375
• jets_at_clarkson.edu

2
Overview

• Basic Concepts in Virtools
• Homework
• Virtools Exercise 1, due today
• Virtools Exercise 2, due Wednesday, 1/23/08
• Complete the Virtools Introduction

3
1. Virtools Authoring

• The authoring application allows you to create
  compositions (CMOs) where 3D objects are given
  behaviors and attributes.
• Virtools is not a modeling application. Other
  applications, such as 3D Studio Max can be used
  to create models, which then can be imported into
  Virtools.

4
2. Behavioral Engine

• The behavior engine, CK2, processes the behaviors
  of how each object acts in a given environment.
• Behavior Building Blocks (BBs) are used to
  create behaviors. Virtools has an extensive
  library of BBs.
• Managers are used to support the behavior engine.
  Examples are the LevelManager, ResourceManager,
  SoundManager HierarchyManager

5
3. Render Engine

• This performs the graphics rendering, and can be
  customized with the SDK it consists of 2 parts
• - CK2_3D determines what should be drawn (list of
  visible items)
• - Virtools Rasterizers, which support Direct X
  and OpenGL, draw the items on-screen

6
4. Web Player

• The Web Player allows playback of a virtools
  application via a web browser.
• Virtools compositions (.cmo) can be exported to
  the Web Player (.vmo)

7
5. Software Development Kit

• The SDK allows you to customize the Behavioral
  Engine and the Render Engine. That is, you can
  write your own functions in C and convert them
  to building blocks.
• create new behaviors or modify existing ones
• create new parameter types
• create media plugins to read any media types
• replace the Virtools render engine with a render
  engine of your choice
• create a custom executable file (.exe)
• modify extend the render engine full source
  code to the rendering engine is provided

8
Creating a Virtual Environment in Virtools
9
Elements of a Composition (CMO)

• BeObject an object to which a behavior can be
  applied
• RenderObject visible in play mode
• Objects that may be visible, but usually are not
  Camera, Curve, Grid, Light
• Objects that are not visible Array, Group,
  Level, Material, Mesh, Place, Scene, Sound,
  Texture

10
Steps to create a composition

• Import objects (ResourcesImport)
• Use the Level Manager to set up the object
• rename it
• double-click the object to get 3D Object Setup
• adjust the world coordinates (0,0,0)
• rotate it as desired
• change the color textures (if desired)
• Add lighting
• Add cameras
• SET INITIAL CONDITIONS

11
Reminders

• Save your composition often (say every 15 mins or
  so, or when you make a change in the objects)
• Set initial conditions whenever you change any
  setting about an object, before you run the
  composition
• A directory has been set up for the class on
  Atlas
• S\Classes\Computer Science\cs461\

12
Basic Concepts in Virtools

• Level Manager organizes the composition
• use to set up objects, lights and cameras
• THEN SET INITIAL CONDITIONS
• Schematic creates edits scripts
• a script describes how an object behaves
• Building Blocks (BBs)
• a library of behaviors, organized by the type of
  behavior and/or by the type of object to which
  the behavior can be applied
• Media objects created in other apps (e.g. Maya)
• e.g. model, sound or image
• Data Resources ResourcesOpen Data Resource
• used to import media objects into the VE

13
3D Entity

• A 3D Entity defines a position, an orientation,
  and a scale
• 3D Frame
• - null object
• - no geometry (invisible)
• - used to provide a referential
• 3D Object
• - have a geometry (i.e. mesh)
• - may have gt1 mesh, but only 1 is active
• - cannot be created within Virtools

14
Shared Mesh and/or Material
Dependency if you delete Kens mug, you will be
asked about dependencies. If you select full,
Andys mug no longer has a shape!
15
Recap Object, Mesh Material
Objects can share a mesh. A mesh can share a
material. If you delete an object that is sharing
a mesh or material, specify no dependencies
(meaning that it will not delete the shared mesh
or material).
16
3D Coordinate System

• defaults to metric (1 unit 1 meter)
• X horizontal Y vertical Z depth
  (Left-handed coordinate system)
• Local coordinate system set when a 3D entity is
  created typically this is 1 corner of the
  bounding box or is the barycenter (geometric
  center) of the entity
• World coordinate system (absolute coordinates)
  shared by all elements in a composition

17
Referential

• point of reference for a 3D transformation (e.g.
  scale, rotate, translate)
• used as a parameter input to a BB (pIn)
• referential value --NULL--
• means the world coordinate system
• referential value name of the entity
• means the local coordinate system

18
Mesh

• Geometry (wireframe)
• triangular faces vertices
• cannot create a mesh in Virtools
• List of materials
• Channels gt 1 layer of material
• Lit mode
• lighting done by Virtools
• prelit static object (done in 3DS or Maya)
• Texture Wrap
• Sharing
• gt1 object can share a mesh
• gt1 meshes can share a material

19
Lights

• There are 3 types of lights in Virtools
• directional light point light spot
  light

directional lt point lt spot (in terms of
complexity)
20
Add Lighting

• Add a spot light
• use the level manager to rename it
• use Setup to position it
• Add directional lighting
• use the level manager to rename it
• use Setup, select Directional
• Position it, say at (0,10,0)
• Change its orientation to (90,0,0)

21
Cameras

• There are 2 types of cameras in Virtools
• Target camera
• - always looking at a target defined by a
  frame
• - cannot specify orientation
• Free camera
• - useful since you can change the
  orientation
• Create Camera button creates both a camera a
  target to get a free camera, delete the target
  using the level manager

22
Camera
23
Rendering

• View Frustrum (view volume)
• defined by the current camera its near far
  clipping planes

24
Building Block

• blue Behavior Inputs (bIn)
• green Behavior Outputs (bOut)
• red Parameter Inputs (pIn)
• violet Parameter Outputs (pOut)

25
Rendering a Frame

• Process Loop
• repeat
• forever

Process Behaviors Render
1 frame
26
BB Operating Cycle

• BB is inactive
• At least 1 input is activated gt BB is activated
• BB reads the input parameters performs its
  function
• At least 1 output is activated
• Some BBs stop here (go back to 1) and others
  reactivate themselves even if no input is active
  (go back to 3)

27
Example Delayer BB
one Behavior In (BIn) / one Behavior Out (BOut)
28
BIn/BOut Building Blocks
Some building blocks have one In and one Out.
The BB starts out as inactive. When you activate
the In, the BB performs its operation, activates
the Out, and becomes inactive. To repeat a
behavior, you must explicitly have a link back to
the behavior In in order to reactivate the
BB. Examples Delayer BB (above), Rotate BB,
Translate BB.
29
Example Timer
one Behavior In (BIn) / one Behavior Out
(BOut) one Loop In / one Loop Out
30
Loop In/Loop Out Building Blocks
Some building blocks have an In, a Loop In, an
Out, and a Loop Out. The BB starts out as
inactive. When you activate the In, the BB
performs its operation and then activates the
Loop Out. To repeat a script, connect from Loop
Out to the looping scripts In, and have a link
from the looping scripts Out back to the BBs
Loop In. When the loop is finished, the BBs Out
is activated. Example Timer BB.
31
Loop In/ Loop Outdetails

• BB is inactive
• In is activated the BB activates Loop Out
  following the pink link BB is still inactive
• We link Loop Out to the script we want to execute
  for the specified time (in this case, 3 seconds).
  To have the timer active again, My Looping
  Script needs to reactivate Loop In. Then, during
  3s, the timer will work following the violet
  link
• Inactive -gt Loop In -gt Active -gt Loop Out -gt
  Inactive
• Finally, when Loop In is activated but the time
  elapsed gt 3s, the timer will work according to
  the orange link and activates Out. The BB is
  inactive. Back to 1.

32
Example Chrono
On / Exit On Off / Exit Off

• also note can use trace mode to display a
  parameter value (such as elapsed time)

33
Activate/Deactivate Building Blocks
Some building blocks, once you activate their On,
the BB stays active until they are explicitly
turned off by activated their Off Examples
Switch On Key BB Chrono BB (above).
34
On/Off Details

• BB is inactive.
• The user presses the 1 key. On is activated, the
  BB performs an action and activates the Out On
  output (violet link). The BB is now active and
  will call itself every frame and perform an
  action until the Off input is activated.
• The user presses the 2 key. Off is activated, the
  BB performs an action and activates the Out Off
  output (pink link). The BB is now inactive. Go
  back to 1.

35
Graphical Flags
36
Construct

• v flag variable number of inputs/outputs
• To add a bIn/bOut or pIn/pOut, right-click in the
  BB and select Construct
• Example Switch On Key BB

37
File Types

• .cmo
• - full composition with both objects scripts
• - FileSave Composition
• .vmo
• - full composition without scripting
• - cannot be loaded by Dev
• - used by Web Player or standalone app
• - FileExport to Virtools Player

38
File Types, cont.

• .nmo
• - 1 or more objects, with or without scripts
• - can be imported into the current composition
• - ResourcesImport File or Import File As
• - Useful for dynamic loading
• .nms
• - contain either a graph or a script
• - to save a script, select it, right click,
  select save as give directory name, in the
  Behavior Graph directory of your resources
  folder give description, version, author name to
  appear in the resource window