Computer Graphics ICS488

Fall 2005OpenGL Programming Lab

(Julian) Yu-Chung ChenEmail: ychen@cs.uic.edu

• 1st week, Aug-25 Thursday CG1 Lab

• How to get started

• What do I need to know to do program assignment 1

• What is OpenGL?

• What OpenGL can and cannot do

• OpenGL and related libraries

• HW/SW implementation

• GLUT

• Programming environment setup

• Platforms, makefile

What’s OpenGL?

• Interface to the graphics hardware

• Hardware independent standard

• Portable design

• Architecture Review Board

• Keep evolving...

• 2.0 GLSL - OpenGL Shading language

What OpenGL can do?

• Control graphics hardware

• Build objects with geometric primitives: points, lines and polygons

• 100+ API(commands)

• Give commands(prefixed ‘gl’)

What OpenGL cannot do?

• No commands for window, user I/O

• No high-level commands

• No models, scene graphs

Implementations

• Hardware

• Graphics card with drivers and libraries

• nVidia, ATI, 3DLabs...

• Software

• Mesa3D (`similar’ to OpenGL - licensing reasons)

• Performance drops dramatically

GL Utility Toolkit

• GLUT

• window definition, control

• system-level I/O

• GLUT is cross-platform

• Make your life easier

GLUT code skeletonSee the shell code

GLUT

• Define & implement callback functions

• Register callback functions to GLUT framework

• Start GLUT main event loop

• glutInit();

• glutInitDisplayMode();

• glutInitWindowSize();

• glutCreateWindow();

• glutDisplayFunc();

• glutKeyboardFunc();

• glutMainLoop();

• New student

• Find your CS account name outside SEO927 (I just got mine!)

• Required libraries

• Ask sysadm install a copy

• Build your own copy

• System setup(remote display?)

CS Department Systems

Install GLUT

• http://www.opengl.org/resources/libraries/glut.html

• ./mkmkfiles.imake; make

• Want shared library? See linux/README

Setup remote display

• X-Window server(with GLX)/client

• Server side:

• xhost + <client_ip>

• Client side:

• DISPLAY=<server_ip>:0

• SSH ForwardX11

• ssh -X <username>@server

Text

Platform dependent issues

• GNU/Linux

• Microsoft Windows

• MacOSX

GNU/Linux

• Use ‘Makefile’

• See Makefile example

• ‘make’ book resources

How to write a Makefile

• Variables

• Make rules and targets

• Remember `tab’ before commands

http://www.gnu.org/software/make/

MS-Windows

• http://www.evl.uic.edu/aej/488/visualc.html

• Make sure your project has a ‘Makfile’(gmake) and can be used directly in CS machines!

MacOSX

• Include three ‘frameworks’: Cocoa, OpenGL and GLUT in Xcode

• Make sure your project has a ‘Makfile’(gmake) and can be used directly in CS machines!

Let’s Get Back to the Shell Program

APIs

OpenGL Command Syntax

• Ex: glVertex3fv()

• 3 -> Number of arguments: 2, 3, or 4

• f -> Data types(i, f, d, b, s, ub, us, ui)

• v -> Formats: ‘v’ for vector format. no ‘v’ means scalar format

OpenGL Primitives

graphics from ref.2

• glClear();

• glColor3f();

• glBegin(); glEnd();

• glVertex2f();

Get more OpenGL example codes

• http://www.mesa3d.org/

• Mesa demos

Resources

1. ‘bluebook’: http://www.rush3d.com/reference/opengl-bluebook-1.0/

2. ‘redbook’: http://www.rush3d.com/reference/opengl-redbook-1.1/

3. ‘redbook’ sample programs: http://www.opengl.org/resources/code/basics/redbook/index.html

4. How to write a Makefile: http://vertigo.hsrl.rutgers.edu/ug/make_help.html