Quality of the SGX driver

[Alemarius Nexus]

Hey,


I would like to know if any of you has experience with the quality of the PowerVR SGX 3D OpenGL driver. I'm currently writing a game based on OpenGL (well, actually an open-source engine to a well known commercial game), and one of the reasons I ordered one was that I wanted to try supporting it on the Pandora (don't know yet if the Pandora really has enough power to run it). However, since I started with this idea I have bought myself a Pandaboard as a mobile development platform, and I am very disappointed of the quality of the SGX driver in it, because I have issues with some of the (admittedly rather less used) core features of OpenGL ES 2.0. In particular, I have problems with depth textures attached to FBOs, these have never worked for me on SGX and I did not get any answer from Imgtec concerning this issue. I believe this is a core feature of OpenGL ES 2.0, and since the GPU and driver in the Pandaboard should be a newer version than what the Pandora has, I fear the same issue will appear on the Pandora, if not worse.


So, any experience that goes farther than just drawing some simple triangles on the SGX, particularly with GLES2?

 

[Exophase]

Depth textures aren't a core feature in OpenGL ES 2, they're an extension: http://www.khronos.org/registry/gles/extensions/OES/OES_depth_texture.txt

 

[Alemarius Nexus]

Ah, right, I remember. But if I remember correctly, the GPU in my Pandaboard claimed to support this extension, so this shouldn't have been a problem either. However, I'll take a look at it again to see if the extension is really listed. Have to install an OS on it again since I haven't used it in a while because not really much was working on it, so it might take some time. Do you know if Pandoras GPU supports this extension?


Thanks in advance.

 

[hdonk]

... I have problems with depth textures attached to FBOs, these have never worked for me on SGX and I did not get any answer from Imgtec concerning this issue.

Did you report this problem on the Forums?

 

[Alemarius Nexus]

Did you report this problem on the Forums?

Yes, I have reported it some time ago here but never got an answer. I haven't pushed the topic since then, because I have actually given up on Pandaboard as a development platform, as it is just way too buggy.


And yes, the GPU claims to support OES_depth_texture.

 

[fusion_power]

I'm not even sure, if there is even one OpenGL ES 2.0 game for Pandora... maybe this has reasons. OpenGL ES 2.0 was once announced of a power feature of the Pandora but it is pretty quiet around it. No clue if it's because of bad drivers or just to complex coding, Pickle does some gles stuff afaik but not sure how far he went.


Would be nice to see more OpenGL ES 2.0 games for Pandora, on paper, the possible features sounds nice (of course).

 

[sebt3]

GLESv2 is rather slow on pandora. But still there are a few gles2 port floating.


Mupen and darkplaces are using it for sure

 

[PokeParadox]

For me... I just haven't got around to getting into the "Shaders" mentality that goes hand in hand with using GLES2.


I'm too used to the legacy way of doing things, but I do realise I need to get to grips with and try and get a working GLES2 renderer going at some point...

 

[hdonk]

Did you report this problem on the Forums?

Yes, I have reported it some time ago here but never got an answer. I haven't pushed the topic since then, because I have actually given up on Pandaboard as a development platform, as it is just way too buggy.


And yes, the GPU claims to support OES_depth_texture.

In that case I won't try to get it followed up.


The good news is the newer Pandoras (GC & 1Ghz) have a supported SGX core in them, so TI should provide much more up to date drivers.

 

[Alemarius Nexus]

It's not that the drivers are so bad that my game will not run at all on them (to be honest I didn't test much longer than a few seconds on SGX each time, so maybe it's even worse), but for a graphically more appealing configuration I will need some of the lesser used features of GLES2. These features are not desperately needed to do what I'm doing (yet), because I could kind of emulate them, but this would go at the cost of some speed, and speed would be a problem even if the advanced features did work. However, if the Pandora drivers suffer from these problems too and speed is too much of a problem, then I can use some different, though lower-quality algorithms instead.

GLESv2 is rather slow on pandora.

How slow is "rather slow"? Sure, I can not expect performance of a desktop GPU, but on my Pandaboard, which has a PowerVR SGX 540, I got around 2-10 FPS for rendering the map of GTA SA, depending on the situation. That's not real-time yet, but that was without some of the optimizations I have now, and I can still turn down the draw distance of the objects to get some more speed.

For me... I just haven't got around to getting into the "Shaders" mentality that goes hand in hand with using GLES2.
I'm too used to the legacy way of doing things (...)

Yeah, in the first place I have been using the fixed-function pipeline of OpenGL 1.X, too. But I don't feel comfortable using a standard that has been deprecated years ago. Also, shaders give me the possibility to create a lot of graphical effects and to offload some of the computationally heavy algorithms to the GPU (for order independent transparancy, for example, which is the algorithm I need the advanced GLES2 features for).


The downside to GL(ES)2 is that you don't find enough good tutorials on the internet to learn it, so buying and reading the OpenGL Programming Guide is a must I think.

The good news is the newer Pandoras (GC & 1Ghz) have a supported SGX core in them, so TI should provide much more up to date drivers.

I hope so. By the way: Are TI or Imgtec the driver developers? As far as I understand, Imgtec are licensing their design to TI and many other vendors, so wouldn't it make more sense for Imgtec to develop the drivers once? After all, this is what Nvidia does, too.

 

[hdonk]

I hope so. By the way: Are TI or Imgtec the driver developers? As far as I understand, Imgtec are licensing their design to TI and many other vendors, so wouldn't it make more sense for Imgtec to develop the drivers once? After all, this is what Nvidia does, too.

TI are IMG's customer. IMG develop both the software and hardware, and license those on to TI. That means that the drivers for OMAP's SGX are provided by TI, but developed by IMG

 

[sebt3]

How slow is "rather slow"? Sure, I can not expect performance of a desktop GPU, but on my Pandaboard, which has a PowerVR SGX 540, I got around 2-10 FPS for rendering the map of GTA SA, depending on the situation. That's not real-time yet, but that was without some of the optimizations I have now, and I can still turn down the draw distance of the objects to get some more speed.

Slower than GLESv1 for doing the same thing. But sure shaders open some gates