OpenCL vs DirectX

OpenCL is not OpenGL

You are thinking about comparing OpenGL with DirectX

On mobile devices OpenGL beats windows, because MS doesn't have a monopoly to push their technology.

Yes as there are more Macs (and people are switching), companies will optimize their openGL implementation. It's already happening with iPhone and iPod touch games.

Developing on a Mac means no recurrent microsoft tax (both developer tools and time and effort to get windows running ok). A lot of developers who started using Macs to develop for iPhone are beginning to realized that. =)

 

OpenGL is to DirectX as OpenCL is to CUDA

You can't compare OpenCL to DirectX in terms of performance. DirectX is a graphics api and OpenCL is a computational api. It just happens to use the GPU to take the processing power. In theory if an application took advantage of the OpenCL api like Rar compression, it would decrease the amount of time by a lot, than it takes to perform the same task on a regular cpu. DirectX does not do that.

Graphics APIs such as DirectX and OpenGL are merely a high level to low level constructor for the GPU to display the information as well as perform mathematical transformations on the given information in real time.

As for developers, there is a difference between the two SDKs. Its completely up to them to write code for a proprietary api or an industry standard api.

EDIT: Actually it's possible, to have both DirectX and OpenCL utilize by a game engine, to improve performance. But thats already been done since OpenCL is essentially a CUDA derivative.