[Bf-committers] Proposal: Blender OpenCL compositor

[Alex Fraser]

Hi Ian,

----- Original Message -----
> because it supports multiple device architectures, a code optimized
> for the GPU won't run fast on the CPU.

I thought you could write kernels optimised for various architectures, and choose the best one at run time. So each node could have one kernel for the GPU and one for the CPU. But an OpenCL GPU kernel will at least run on the CPU, even if it does so sub-optimally; and vice versa.

> Then there is the question of user's having the hardware to even run
> it, necessitating a CPU only fall-back.

Do you mean two entirely separate codes? Or could we have one implementation that uses OpenCL, but with a CPU kernel (also written in OpenCL) to fall back on? That would seem ideal, since you can develop just one kernel to start with, and add architecture-specific kernels at a later time.

Is the problem that there are no free OpenCL libraries (e.g. for use without a GPU)?

Cheers,
Alex