On Feb 23, 2013, at 11:15 PM, Benoit Jacob <jacob.benoi...@gmail.com> wrote:
> The biggest disadvantage of OpenVG is that it is a whole new surface of > contact with drivers. We're only just now digesting the surface of OpenGL and > gralloc drivers, in terms of driver bugs and other device-dependent behavior. > So the prospect of throwing OpenVG into the mix is scary and unexciting, and > so the bar has to be very high. In addition to performance comparisons I > would have to hear a good reason to believe that OpenGL+software can't be as > fast as OpenVG -- is it because OpenGL doesn't efficiently expose the > hardware features, or is it because there is OpenVG-specific hardware? Scary and unexciting are not strong reasons to miss out on potential gfx performance wins, especially on low-end mobile hardware. From reading up on two chipset specs, both Adreno and Mali seem to have special dedicated hardware for OpenVG (for tessellation I am guessing). If we find OpenVG too unstable for the broad set of Android hardware, we can always limit OpenVG use to B2G devices where we can work with the vendor. Andreas > > Benoit > > 2013/2/23 Andreas Gal <g...@mozilla.com> > > OpenVG is a Khronos standard API for GPU accelerated 2D rendering. Its very > similar to OpenGL in design. In fact, its an alternative API to OpenGL ES on > top of EGL. It looks like that OpenVG is supported on most Android devices > and is used there by Flash (or well used to be used). B2G devices have OpenVG > support as well. There are also a number of open source implementations of > OpenVG that use OpenGL to accelerate 2D operations that might be interesting > for the desktop. OpenVG is pretty similar to Cairo and Skia when it comes to > the actual operations offered. The biggest drawback of OpenVG is that it > doesn't mix well with OpenGL. Its possible to render with OpenVG to a texture > and then composite that with OpenGL, but its not possible to do mixed > rendering with VG and GL to the same surface. That having said, I still think > we should consider adding an OpenVG backend. It would potentially > significantly speed up rendering on mobile hardware. OpenVG is quite a bit > more seasoned t > han Skia/SkiaGL, and explicitly targets mobile, whereas SkiaGL seems to be > mostly optimized for the desktop (at least so far). A particular advantage of > OpenVG is that it can take advantage of dedicated 2D acceleration hardware > (Mali and Adreno both have special 2D hardware OpenVG uses). SkiaGL on the > other hand is limited to using GLES to accelerate 2D drawing operations. What > do people think. Should we add a OpenVG backed? > > Andreas > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform > _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
