OPENGL- Bipindra Bir Shrestha

AGENDA

Introduction to OpenGL Demo Programming in OpenGL Demo References

WHAT IS OPENGL?

An application programmer’s interface (API) that allows programmers to write programs that access graphics hardware.

BENEFITS

It is close enough to hardware so that programs written with OpenGL run efficiently

It is easy to learn and use.

THREE VIEWS OF OPENGL

1. Programmer’s View

2. The OpenGL State Machine

3. The OpenGL Pipeline

THE PROGRAMMER’S VIEW

Specify Geometric Objects Describing properties of these objects Defining how these objects should be viewed

THE OPENGL STATE MACHINE

Function Call

Pixels

THE OPENGL PIPELINE

OPENGL FUNCTIONS Primitive functions

Geometric : polygons Discrete : bitmap

Attribute functions Control attribute of primitives. Eg color, line type,

light sources , textures Viewing functions

Determine properties of Camera. Input functions

Allow us to control windows on the screen and to use the mouse and keyboard

Control functions Allow us to start and to terminate OpenGL

programs and to turn on various OpenGL features.

OPENGL VERSIONS AND EXTENSIONS OpenGL is controlled by OpenGL Architectural Review

Board (ARB), which has members from companies such as SGI,IBM and Microsoft.

Present version is 2.1 . Next version 3.0, release date is not yet announced due to some issues.

OpenGL is very stable and has lower compatibility. Extensions: allow vendors to provide additional

functionality through extensions. Each vendor has alphabetic abbreviation .

E.g: glCombinerParameterfvNV() : NV for NVDIA

If many vendors agree on same implementation it becomes “Standard extension” abbriviated with ARB. Eg. GL_ARB_multitexture

LANGUAGES C C#: The framework Tao for Microsoft .NET includes OpenGL

between other multimedia libraries Delphi: Dot[4] Fortran: f90gl supports OpenGL 1.2, GLU 1.2 and GLUT 3.7 [5] Java:

Java Bindings for OpenGL (JSR 231) and Java OpenGL (JOGL) Lightweight Java Game Library (LWJGL)

Lisp: See the cl-opengl project at common-lisp.net Perl:

Perl OpenGL (POGL) module - shared libs written in C C vs Perl and Perl vs Python benchmarks

PHP: See http://phpopengl.sourceforge.net/ Python: PyOpenGL supports GL, GLU and GLUT [8] Ruby: See [9] - supports GL, GLU and GLUT Smalltalk as seen in Croquet Project running on Squeak

Smalltalk Visual Basic: ActiveX Control

CONFIGURING VISUAL STUDIO 2005 Download GLUT binaries for windows from “Nate

Robins” ‘s website http://www.xmission.com/~nate/glut.html

put the files as

Make sure visual studio c++ projects links in the GLUT/gl/glu libraries. Goto:

Menu: “Project -> (your-project-name) Properties” Tab: “Configuration Properties -> Linker -> Input” Under “Additional Dependencies”, add “glut32.lib opengl32.lib

glu32.lib” Under Configuration Properties->C++->General->Additional Include Directories : add "C:\Program Files\Microsoft Visual Studio 8\VC\PlatformSDK\Include"

File Location

glut32.dll C:\WINDOWS\system\ (or system32)

glut32.lib C:\Program Files\Microsoft Visual Studio 2005\VC\PlatformSDK\Lib

glut.h C:\Program Files\Microsoft Visual Studio 2005\VC\PlatformSDK\Include\gl

DEMO

PROGRAMMING IN OPENGL -1

GLUT Initialize :

void glutInit( int argc, char ** argv) Creating a window

int glutCreateWindow(char * title) Display Function

void glutDisplayFunc(void (*func)(void)) Main Loop

void glutMainLoop()

PROGRAMMING IN OPENGL -2 Drawing a rectangle

glBegin(Glenum mode) glEnd() void glVertex{2 3 4}{sifd}(Type xcoordinate,……)

void glClear(Glbitfield mask) void glFlush()

Changing GLUT defaults void glutInitDisplayMode(unsigned int mode)

void glutInitWindowSize(int width,int height)

void glutInitWindowPosition( int x, int y)

PROGRAMMING IN OPENGL -3 Setting Colors

void glColor*() void glClearColor( Glclampf r, GLClampf g, Glclampf b,

Glclampf a ) Two Dimensional Viewing

void gluOrtho2D( Gldouble left, Gldouble right, Gldouble bottom, Gldouble top)

Coordinate Systems and Transformation glMatrixMode( GL_PROJECTION ); glLoadIdentity();

Points glPointSize(2.0);

Lines GL_POINTS, GL_LINES, GL_LINE_STRIP, GL_LINE_LOOP

in glBegin( GL_LINES ); Enabling OpenGL features

void glEnable( Glenum feature) void glDisable( Glenum feature )

PROGRAMMING IN OPENGL -4

Rectangles void glRect{ sifd} ( TYPE x1,y1,x2,y2 )

Text void glutBitMapCharcter( void * font, int char )

Save the state void glpushMatrix() void glPopMatrix()

Viewport void glViewport( Glint x, GLint y, Glsizei w, Glsizei h )

INTERACTION AND ANIMATION

Reshape and Idle Callback Double buffering Using keyboard and mouse Mouse motion Subwindows and Multiple Windows

THREE-DIMENSIONAL PROGRAMMING

Cameras and Objects Orthographic Projections in OpenGL Vertex Arrays Hidden Surface removal GLUT Objects

TRANSFORMATION

Translation Rotation Scaling Setting vertices directly

LIGHTS AND MATERIALS

Enabling and disabling OpenGL lighting Specifying Light source Controlling the Lighting Calculation Smooth Shading Transparency

IMAGES

Pixels and Bitmaps Displaying a bitmap Mixing Bitmaps and Geometry Colors and Masks Drawing Modes Reading and Writing Pixels Selecting Buffers Luminance Pixel Zoom

TEXTURE MAPPING

Texture Coordinates Texture Parameters Applying textures to surface Minimaps

CURVES AND SURFACES

Bezier Curves and surfaces One dimensional OpenGL evaluators for

Bezier Curves Two dimensional evaluators to evaluate

Bernstein polynomials and to form Bezier surfaces.

DEMO

RESOURCES

Official Website : http://www.opengl.org/ SDK : http://www.opengl.org/sdk/ Reference pages :

http://www.opengl.org/sdk/docs/man/ GLUT :

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

Sample Projects at : http://www.ziyoo.com/