Further Programming for 3D applications CE Introduction to Further Programming for 3D application Bob Hobbs Faculty of Computing, Engineering and Technology Staffordshire University

Outline Module Details Module Details What is 3D programming? What is 3D programming? Typical Processing Steps Typical Processing Steps Modelling and Rendering Modelling and Rendering Applications Applications Summary Summary

Module Details Teaching Team Teaching Team –Bob –Dr. Len Noriega Semester 115 cats Semester 115 cats 3 Hours per week 3 Hours per week –1 Hour Lecture Tue 12pm –2 Hours Practical Mon 1pm, Tue 4pm & Thu 9am

Module Details Course Handbook & Lecture Notes Assignment Details 50% assignment work 50% assignment work 50% two hour exam 50% two hour exam

Program of Study Week 01 Introduction Week 01 Introduction Week 02 General 3D concepts, Motion and Collision Week 02 General 3D concepts, Motion and Collision Week 03 Manipulating the Matrix stack Week 03 Manipulating the Matrix stack Week 04Model Importation and Binary File handling Week 04Model Importation and Binary File handling Week 05Model Interaction and Viewing transforms Week 05Model Interaction and Viewing transforms Week 06Windowing and GUI elements Week 06Windowing and GUI elements Week 07 Lighting and Shading Techniques Week 07 Lighting and Shading Techniques Week 08Lighting and Shading Techniques Week 08Lighting and Shading Techniques Week 09Textures & Texture Mapping Week 09Textures & Texture Mapping Week 10LOD, Mipmapping, tesselation Week 10LOD, Mipmapping, tesselation Week 11 Vertex and Pixel Shading Week 11 Vertex and Pixel Shading Week 12Assessments Week 12Assessments

Hierarchy of Models Geometry Physics Bio-Mechanics Behaviour

How does this work ? Simulation Loop Simulation Loop –read input sensors –update objects –render scene in display Uses traditional 3D graphics methods to render or ‘draw’ the scene Uses traditional 3D graphics methods to render or ‘draw’ the scene

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

Introducing OpenGL Graphics basics: 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) Implementing all this is a lot of work (surprise) OpenGL provides a standard implementation OpenGL provides a standard implementation –So why study the basics?

OpenGL Design Goals SGI’s design goals for OpenGL: SGI’s design goals for OpenGL: –Hardware independence without sacrificing performance –Natural, concise API with some built-in extensibility OpenGL has become a standard because: OpenGL has become a standard because: –It doesn’t try to do too much Only renders the image, doesn’t manage windows, etc. Only renders the image, doesn’t manage windows, etc. No high-level animation, modeling, sound (!), etc. No high-level animation, modeling, sound (!), etc. –It does enough Useful rendering effects + high performance Useful rendering effects + high performance –It is promoted by SGI (& Microsoft, half-heartedly)

OpenGL: Conventions Functions in OpenGL start with gl 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/# 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

OpenGL: Specifying Geometry Geometry in OpenGL consists of a list of vertices in between calls to glBegin() and glEnd() 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... Points, lines, polygons, triangles, quadrilaterals, etc...

What is 3D rendering? Object Viewer Generally deals with graphical display of 3D objects as seen by viewer Synthetic image will vary according to: viewing direction, viewer position, illumination, object properties,... Projection onto 2D surface

What is 3D Computer Graphics? 3D graphics: generation of graphical display (rendering) of 3D object(s) from specification (model(s)) 3D graphics: generation of graphical display (rendering) of 3D object(s) from specification (model(s)) Specification Modelling Graphical display Rendering such as

Wireframe polygonal modelSolid object Vertices Viewpoint Typical Processing Steps Facets Transformation Hidden surface removal Light source Shading

Object model(s) Illumination model Viewing and projection specification Graphics engine Graphical display Rendering: operations that produce view of scene projected onto view surface Modelling: numerical description of scene objects, illumination, and viewer Typical Processing Steps

Modelling Human Head Model 1438 facets

Modelling Human Head Model 7258 facets

Modelling Teacher and Board Model 2074 facets

Rendering Shaded Human Head 1438 facets

Rendering Shaded Human Head 7258 facets

Rendering Shaded Teacher and Board

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

Simple scene graph Fog node Light node Root node Group node Xform node Geom node

Scene Graph Nodes Content Nodes Content Nodes –contain basic elements of a scene geometry geometry light light position position fog fog Group Nodes Group Nodes –no content –link the hierarchy –allow grouping of nodes sharing a common state Parent Child #1 Parent Child #2

Example Hierarchy Geom Lampost Xform T2 Geom Dog Xform T1 Group “Dog” Group “Lampost” Light Root

Applications VR programming is used in many applications, e.g. 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

Summary Simulation consists of a series of scenes 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 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 Each iteration of the simulation loop determines actions, translations(along paths) and other inputs which affect properties of the objects NOT animation !!! NOT animation !!! The world is redrawn using rendering process The world is redrawn using rendering process