paul's opengl page

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consultancy work for AITI borland c & glut source loading objects texture coordinates mail links

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introduction I posted this page to help people who fancied trying a bit of OpenGL, but didn't know where to start.

I saw the same questions pop up on the news groups and message boards that I asked when I first started. I figured that it'd be helpful to take you through the process, learning by example. This to me seems the best way to learn the fundamentals of OpenGL quickly.

what this page won't show you is.. how to write the next QuakeIII game, anything to do with BSP trees, oct trees, terrain generation, particle systems, inverse kinematics, quaternion math libraries, skeletal animation, <insert your own fashionable buzz-word here>

what this page will show you is.. well annotated C source that displays core and extended OpenGL functionality clearly and succinctly.

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what's new?

11 Aug 01:
I've uploaded a tutorial on using the GLU Tessellator. [Program11] shows you how to setup these functions, useful for creating convex and non planar polygons. The page on SDL is almost ready, as well as some pages devoted to programming languages, their design and implementation.

5 Mar 01:
Jonas Geduldig pointed out some pointer errors in the latest tga loading code - he also suggested a fix for them. All the affected archives have been updated. If you don't want to re-download all the examples, you can grab it separately from [here] Thanks again Jonas!

It shouldn't crash when it can't find the .tga file anymore either :)

31 Jan 01:
I'm still here! I haven't been doing too much OpenGL though. I've been playing with [SDL], a cross-platform graphics and sound library - I plan to put a few pages up on that soon. If you have any OpenGL questions please do keep them coming, especially suggestions for further tutorials... I'll get back to OpenGL just as soon as I get bored with SDL :)

Still waiting for my Microsoft eMbedded Tools SDK. Can't wait to have a play around with WindowsCE...

9 Nov 00:
Changed some stuff around on the site. I've dropped paletted texture support in my .tga loading code, very few cards seem to support it these days and the code was getting pretty unmanageable. That means I've 'refocused' program5 - it just talks about loading real file formats now - you can still load RLE compressed .tga files though... You can get the latest revised version from [here], or re-download programs 5 - 10.

31 Oct 00:
Posted [program10], it deals with hardware multitexturing and vertex arrays. I also finished re-writing the .tga loader. There are some issues with compressed textures on the Radeon, so I'd appreciate feedback for other cards that support compressed textures.

24 Oct 00:
I've bought a new video card! I got the 64 meg version of the ATI Radeon. Anyway, this thing is extension packed so expect an updated multi-texturing tutorial some time soon. The .tga loader is undergoing another overhaul - large chunks of it are being rewritten from scratch to accommodate another extension - ARB_compressed_textures.

I've also noticed that Milkshape3D's file format has been updated, so my object loading code is a little out of date. When I've got the time I'll upgrade that.

what's next? Probably have a go at NURBS and other higher order surfaces next...

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borland C, Borland C++ has been floating around for free on magazine coverdiscs for a while now. It's the compiler I use, so all of the source here is geared toward it. If you don't know how to compile OpenGL programs two tutorials are available:

Borland C++ with IDE Borland gave away version 4.5 of their compiler and development environment last year. The magazine "PCPro" had it on their May coverdisc in the UK

Borland C++ 'free command line' The latest version of the BCC32 compiler is downloadable from Borland's website at no cost. BCC32 forms the 'core' of all their C++ products. As there is no development environment (no text editor, no nothing) compiling is a little more involved - but hey, it's free!

glut... Without glut to open windows for us we'd have to use Win32 code. There are many many Win32 tutorials on the web if you're interested in that sort of thing. But let's face it, if you're trying to get your head around OpenGL you don't want Win32 getting in the way.

The glut32.lib supplied in precompiled form from SGI only has import libraries for Microsoft compilers. These don't work with Borland, so we have to use a utility to make our own glut32.lib.

You can download version 3.6 of the .dll and Borland .lib [locally]. Put the glut32.h file in your compiler's "/include/gl" directory. Put the glut32.lib in a place you can easily remember. I put mine in "/libs" directory.

Additionally, its useful to have a late version of the gl.h file. Then you can be sure of having all the newest OpenGL extension function pointers and tokens. Download that [locally] too.

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source Clicking on a program title takes you to the description and screenshot for that program. The abridged source will be present - and if we introduce a new opengl function, I'll make it a hyperlink to the relavant opengl manual page.

Program template 26 Aug 99 [download]: The simplest glut program you can create; this opens a window and not much else. It's a useful starting point though.

GLU Primitives and Lighting 31 Aug 99 [download]: A solid glu sphere is drawn and we make the calls necessary to setup OpenGL lighting.

Simple texture mapping 13 Sep 99 [download]: We write a simple function to load a binary image from disc and wrap it around our glu sphere. Our grey ball becomes the planet Earth.

Texture Objects 25 Oct 99 [download]: The glBindTexture function is introduced to load and manage more than one texture at a time. The Earth gets some cloud cover

Texture Palettes 16 Mar 00 [download]: The texture loader function is replaced with a library that loads .tga files. OpenGL extensions are explored when we use them to load 8-bit paletted .tga files.

Vertex Arrays 30 Oct 99 [download]: Vertex arrays are introduced as well as the often used vertex array 'locking' extensions.

Multitexturing 16 Mar 00 [download]: We 'fake' multi-texturing by blending two rendering passes together, just like in the old days.

Alpha Channel 31 Mar 00 [download]: A neat trick to render trees and other complex shapes is explored. Transparency is useful!

Selection and glut text 15 Jul 00 [download]: Opengl's selection mode is explained as well as getting fonts onto the screen with glut.

Hardware Multi-Texturing and Vertex Arrays 31 Oct 00 [download]: Could this be? Finally I get around to writing another tutorial! From the message boards it seems as though a lot of people find multi-texturing with vertex arrays a black art. This tells you how to set everything up.

GLU Tessellator 11 Aug 01 [download]: Setting up the GLU tessellator isn't as self explanatory as it could be, so this page tells you how.

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other projects.. Okay, so I lied! Like everyone else, I've got plenty of other stuff on the go at the moment, most is unfinished and not worth bothering about yet. As well as the solar system below, I'm working on 'proper' object simulation using multithreaded scene graphs, a quaternion class with a useful set of features and an object loader.

[Solar system] On going: I used to go to UMIST in Manchester -- for our Computer Graphics module we had to write a simple solar system simulation. It didn't have to be accurate, it just had to work.

Since then my solar system has become something of a test bed. The latest incarnation [29 Oct 99] includes proper camera motion / control through Euler angles. It simulates the positions of all the entities using better maths - this is based on the computer system clock and not frame rate.

[loading objects] from a modeler is useful, as well as [generating texture coordinates] from the loaded data. Take a look at the pages to see how.
Scene management and simulation is the next step. In other words, we'll be looking at ways of storing and manipulating data for all your objects...

visits since March 2000

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