Question

I want to know some examples for usage of OES_get_program_binary. In other words, I want to know some examples in which program binaries are really useful. In particular, I want to know the scenarios. Thanks.

Answer 1

The utility of OES_get_program_binary is outlined pretty clearly in the extension specification itself.

On OpenGL ES devices, a common method for using shaders is to precompile them for each specific device. However, there are a lot of GPUs out there. Even if we assume that each GPU within a specific generation can run the same precompiled shaders (which is almost certainly not true in many cases), that still means you need separate precompiled shaders for Tegra2, one for PowerVR Series 5 GPUs, PowerVR’s series 5X, and Qualcomm’s current GPU. And that doesn’t take into account next-gen mobile GPUs, like PowerVR Series 6 and Tegra 3, and whatever Qualcomm’s coming out with next. And any number of other GPUs I haven’t mentioned.

The only alternative is to ship text shaders and compile them as needed. As you might imagine, running a compiler on low-power ARM chips is rather expensive.

OES_get_program_binary provides a reasonable alternative. It lets you take a compiled, linked program object and save a compiled binary image to local storage. This means that, when you go to load that program again, you don’t have to load it from text shaders (unless the version has changed); you can load it from the binary directly. This should make applications start up faster on subsequent executions.