openGL

1. openGL - Bipindra Bir Shrestha

2. Agenda • Introduction to OpenGL • Demo • Programming in OpenGL • Demo • References

3. What is OpenGL? An application programmer’s interface (API) that allows programmers to write programs that access graphics hardware.

4. Benefits • It is close enough to hardware so that programs written with OpenGL run efficiently • It is easy to learn and use.

5. Three Views of OpenGL • Programmer’s View • The OpenGL State Machine • The OpenGL Pipeline

6. The programmer’s View • Specify Geometric Objects • Describing properties of these objects • Defining how these objects should be viewed

7. The OpenGL State machine Function Call Pixels

8. The OpenGL Pipeline

9. 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.

10. 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

11. 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

12. 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"

13. DEMO

14. 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()

15. 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(intwidth,int height) • void glutInitWindowPosition( int x, int y)

16. 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 )

17. 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 )

18. Interaction and animation • Reshape and Idle Callback • Double buffering • Using keyboard and mouse • Mouse motion • Subwindows and Multiple Windows

19. Three-Dimensional Programming • Cameras and Objects • Orthographic Projections in OpenGL • Vertex Arrays • Hidden Surface removal • GLUT Objects

20. Transformation • Translation • Rotation • Scaling • Setting vertices directly

21. Lights and Materials • Enabling and disabling OpenGL lighting • Specifying Light source • Controlling the Lighting Calculation • Smooth Shading • Transparency

22. 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

23. Texture Mapping • Texture Coordinates • Texture Parameters • Applying textures to surface • Minimaps

24. 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.

25. DEMO

26. 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/