Reccomended GLSL version to use with Irrlicht

[tasulife]

I would like to experiment with shaders and irrlicht to explore the world of shadow mapping, deferred shading, bloom, HDR and other modern rendering techniques. However, I don't really know what GLSL version to commit to writing these shaders in.

Here is my criteria for choosing a GLSL version, in descending order of importance:
- I would like to have a good feature set, which will allow me to implement *most* of the cool shader techniques on the web without writing huge functions to replace missing functionality in earlier GLSL versions.
- I would like to avoid having to write code that changes the irrlicht binary if possible. However, I can be persuaded with the argument "if you make this quick change to Irrlicht, you can unlock a ton of shader power".
- The shader version should work on the vast majority of computers deployed in the world

So, how do I get the most bang for my buck with GLSL and Irrlicht "out of the box"?

Thank you!

[Nadro]

Irrlicht has OpenGL 2.1 driver, thats why you should choose GLSL 1.2.

[hendu]

1.10 and 1.20 run on every GL2 driver, 1.30 gives more features while still running on most (may require DX10-level gpu). You can use 1.30 without any irr changes.