Imagination PowerVR SDK Blog

GL_EXT_frag_depth support with PowerVR 544MP3?


Can you work with Samsung to bring the GL_EXT_frag_depth OpenGL extension to the Galaxy S4? This is the only limitation for bringing my application to the Galaxy S4 Exynos 5410 model compared to the OpenGL ES 3 capable Adreno 320 model.



Our hardware is capable of supporting this feature, but the extension is not implemented in our reference driver at this time.

Do you need this extension for spherical billboard rendering, or something similar?




I’ve been working on porting a Gamecube/Wii emulator to portable devices and the fragment depth is required for emulation of the device’s z-textures and also the correct emulation of pixel depth.


How are you creating Z-textures? Do you need the EXT_frag_depth extension for this?

What sort of depth correction are you doing with the EXT_frag_depth extension?

Depending on the correction you’re implementing, it may be possible to modify the way in which depth tests are performed instead of relying on the extension.




Without delving in to the heart of our massively convoluted fragment shaders, it’s hard to explain exactly why it is necessary, but we use textures provided by the emulated console to determine the depth at that stage of the video emulation.

It’s a hard requirement that can’t be removed sadly.


It /is/ a bit disappointing that I have to tell people to buy the GS4 to use my application, then further specify the model as well. It would be extremely nice if I could just say, GS4, or any PVR54x device.


Unfortunately, even if we were to implement the GL_EXT_frag_depth extension in our reference driver we have no control over the release schedule of graphics drivers on our customer’s platforms. You should contact Samsung to see if they will consider adding this feature.




Wouldn’t other companies have a higher chance of implementing it if it is implemented in your reference driver? I don’t mind too much if it were the GS4 or any of the many other PVR5 phones available to the market.


Yes. However, I can’t publicly comment on our reference driver roadmap.




Alright, I’ll just wait for PowerVR6