Ian Bullard

I've been working on an OpenGL ES project for a presentation to CocoaCoder.org to help people in the group understand OpenGL better and to get better performance.  My frustrations with the presentation led me to release my math library so people can spend time learning OpenGL instead of writing matrix math functions.  The project has ended up being a very simple sprite engine that supports OGL ES 1.1 and 2.0.  

The CocoaCoder_OpenGLES project isn't a bunch of code I'm particularly proud of but it is a good example of 2D sprite rendering.  It's also a good example of using shaders on the iPhone, although I have only been able to test it against the simulator and not an iPhone 3GS.  

Check the project out, play with it and give me any feedback you have.  I'm going to continue working on the project over the next couple of months and use it in future blog posts.

I've been working on OpenGL ES tutorials for a while and I always hit the same wall: a lack of vector and matrix support. For DirectX there's D3DXVECTOR4 and D3DXMATRIX which make it much easier to get started. For OpenGL you have some support via the matrix stack and glOrthof/glRotatef/etc. but OpenGL ES 2.0 takes even that away from you.

Several years ago I wrote a math library that included everything from sine and cosine to transformations. It's overkill for simple 3D mathematics and a lot of it is organized in preparation to create a ray tracer. MathLib is what I use for all of my own OpenGL rendering, though, and does a good enough job for most cases.

To give back to the community and save myself some sanity moving forward I've decided to release the MathLib part of my code library under the MIT license. Download it, check it out, and try it out. I'll release source code that shows how it's used with OpenGL ES shortly.

[EDIT: here's a quick example on how to use the library's transformations with OpenGL]

glMatrixMode(GL_PROJECTION);

Transform4f ortho(Transform4f::Orthographic(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f));

Matrix4x4f mat(ortho.GetTransform());

glLoadMatrixf((float*)mat);

glMatrixMode(GL_MODELVIEW);

Transform4f rot(Transform4f::RotateZ(rotation * 0.0174532925f));

mat = rot.GetTransform();

glLoadMatrixf((float*)mat);