Texture Cache / Mapping about vita3k

[petmac]

I don't actually think we can map texture data, unless we want to implement texture sampling ourselves, because the host texture format (most likely NVIDIA, AMD, Intel) will be different to the Vita's (PowerVR).

A texture cache was implemented in #258 which I think is as good as we can get without reimplementing texture sampling.

That's not to say we can't use mapped buffers to upload vertex and index data, but I don't think there's a fast path to keep the OpenGL buffers in sync. We would need to hash mapped memory and call glBufferSubData (I think) to upload the changes. This may be faster than what we do now (upload every draw call) so it's probably worth looking at as an optimisation, if it's visible in the profiler.

What do you think @frangarcj ?

[pent0]

Texture cache added, mapping seems not possible on all API sadly :( Performance can be improved without texture mapping.