Development of Simulation and

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Development of Simulation and Virtual
Reality CM30008-2
School of Computing Staffordshire University
Introduction to Development of Simulation and
Virtual Reality
Bob Hobbs
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Outline

• Module Details
• What is VR programming?
• Typical Processing Steps
• Modelling and Rendering
• Applications
• Summary

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Module Details

• Teaching Team
• Bob Hobbs r.g.hobbs_at_staffs.ac.uk
• Dr. Len Noriega l.a.noriega_at_staffs.ac.uk
• Sam Wane s.o.wane_at_staffs.ac.uk
• 2 Semesters 20 cats
• 2 Hours per week
• Semester 1 SoC
• Semester 2 SEAT

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Module Details

• Course Handbook Lecture Notes
• http//www.soc.staffs.ac.uk/cmtrgh
• Assignment Details
• 25 Assignment 1 - practical
• 25 Assignment 2 Report
• 50 Exam

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Hierarchy of Models
Behaviour
Bio-Mechanics
Physics
Geometry
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How does this work ?

• Simulation Loop
• read input sensors
• update objects
• render scene in display
• Uses traditional 3D graphics methods to render or
  draw the scene

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Simulation Loop
Read Sensors
Check any defined actions
Update objects with sensor input
Objects perform tasks
Step along any defined paths
Render universe
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Introducing OpenGL

• Graphics basics
• Transform geometry (object ?world, world ?eye)
• Apply perspective projection (eye ?screen)
• Clip to the view frustum
• Perform visible-surface processing (Z-buffer)
• Calculate surface lighting etc.
• Implementing all this is a lot of work (surprise)
• OpenGL provides a standard implementation
• So why study the basics?

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OpenGL Design Goals

• SGIs design goals for OpenGL
• Hardware independence without sacrificing
  performance
• Natural, concise API with some built-in
  extensibility
• OpenGL has become a standard because
• It doesnt try to do too much
• Only renders the image, doesnt manage windows,
  etc.
• No high-level animation, modeling, sound (!),
  etc.
• It does enough
• Useful rendering effects high performance
• It is promoted by SGI ( Microsoft,
  half-heartedly)

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OpenGL Conventions

• Functions in OpenGL start with gl
• Functions starting with glu are utility functions
  (i.e., gluLookAt())
• Functions starting with glx are for interfacing
  with the X Windows system (i.e., in gfx.c)
• Function names indicate argument type/
• Functions ending with f take floats
• Functions ending with i take ints, functions that
  end with v take an array, with b take byte, etc.
• Ex glColor3f() takes 3 floats, but glColor4fv()
  takes an array of 4 floats

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OpenGL Specifying Geometry

• Geometry in OpenGL consists of a list of vertices
  in between calls to glBegin() and glEnd()
• A simple example telling GL to render a triangle
• glBegin(GL_POLYGON)
• glVertex3f(x1, y1, z1)
• glVertex3f(x2, y2, z2)
• glVertex3f(x3, y3, z3)
• glEnd()
• Usage glBegin(geomtype) where geomtype is
• Points, lines, polygons, triangles,
  quadrilaterals, etc...

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What is 3D rendering?
Generally deals with graphical display of 3D
objects as seen by viewer
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What is 3D Computer Graphics?

• 3D graphics generation of graphical display
  (rendering) of 3D object(s) from specification
  (model(s))

Modelling
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Typical Processing Steps
Wireframe polygonal model
Solid object
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Typical Processing Steps
Modelling numerical description of scene
objects, illumination, and viewer
Rendering operations that produce view of scene
projected onto view surface
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Modelling
1438 facets
Human Head Model
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Modelling
7258 facets
Human Head Model
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Modelling
2074 facets
Teacher and Board Model
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Rendering
1438 facets
Shaded Human Head
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Rendering
7258 facets
Shaded Human Head
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Rendering
Shaded Teacher and Board
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Scene Graphs

• In VR programming the structure used is a scene
  graph which is special tree structure designed to
  store information about a scene.
• Typical elements include
• geometries
• positional information
• lights
• fog

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Simple scene graph
Root node
Fog node
Light node
Group node
Geom node
Xform node
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Scene Graph Nodes

• Content Nodes
• contain basic elements of a scene
• geometry
• light
• position
• fog
• Group Nodes
• no content
• link the hierarchy
• allow grouping of nodes sharing a common state

Parent
Child 1
Child 2
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Example Hierarchy
Group Lampost
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Applications

• VR programming is used in many applications, e.g.
• Entertainment (computer games, movie special
  effects, ...)
• Human computer interaction (GUI, ...)
• Science, education, medicine (visualisation )
• Business (marketing, ...)
• Art

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Summary

• Simulation consists of a series of scenes
• Objects defined as Scenes in a scene graph which
  may be one object or a related collection of
  objects
• Each iteration of the simulation loop determines
  actions, translations(along paths) and other
  inputs which affect properties of the objects
• NOT animation !!!
• The world is redrawn using rendering process