Nokia 500 graphics acceleration

[mikpeson]

Nokia 500 comes with 1 GHz CPU. Unfortunately Nokia 500 does not include 3D graphics accelerator HW and therefore there is no OpenGL ES API in this device. However, there is 2D acceleration HW and OpenVG API for that.

Qt automatically uses OpenVG rendering backend for this device and your Qt apps will run faster compared to non 2D/3D accelerated devices (N97 mini). I have measured the peak performance of this device and you can have fillrate of 30 Mpixels/s with transparent pixels (QPainter drawImage). This means you can fill the NHD resolution screen 4.3 times at 30 fps. I think this is enough performance for some simple 2D casual games.

We are planning to create new version of the EPONG game that will support direct OpenVG rendering. I hope this example will help some of the developers that want to learn OpenVG basics and how to use that API directly from Qt.

Br,
Mika

[lucidmind]

Looking forward to that. Funny that OpenGL ES isn't available without acceleration. 1GHz would be quick enough for simple stuff though I guess there isn't that much demand for it.

[AtifGulzar]

Hi Mike,

It seems Direct OpenVG rendering will be much faster than the default QT with backend OpenVG? We are looking to achieve around 60 fps on Nokia 500.

After little bit of google it seems that we need to build QT for direct OpenVG use http://doc.qt.nokia.com/stable/openv...openvg-support . Would you please suggest which OpenVG implementations should we use? There are references for ShivaVG (OpenGL based) in the official documentation but at the same time it also recommends for EGL based implementation. Thanks

regards,
Atif

[mikpeson]

Unfortunately display refresh rate is limited to 30 fps in Nokia 500. QtPainter will automatically use OpenVG rendering backend so it will benefit from the acceleration. However, you might be able to get more performance if you use directly OpenVG and if you have the full OpenVG API feature set.

I would recommend you to develop directly with Nokia 500 and not to use any SW OpenVG emulation drivers as you really won't get exact performance. OpenVG works also with N8 and other Symbian devices but the performance will be much better on these devices compared to Nokia 500.

We are going to publish a new project (https://projects.developer.nokia.com/spritebatchqt) that uses OpenVG in couple of weeks.

[AtifGulzar]

Thanks Mike,

However, you might be able to get more performance if you use directly OpenVG

Would you please direct me how can I use OpenVG directly? Do I really need to build QT from scratch as mentioned in reference document

I would recommend you to develop directly with Nokia 500

you mean with default QT development?

profound regards,
Atif

[jmagic]

Qt 4.7 has an example of OpenVG rendering at examples/openvg/star directory.

Basically, you just write

painter.beginNativePainting();

/* do the openvg stuff here, like this: */
static VGfloat backgroundColor[4] = { 0.0f, 1.0f, 0.0f, 1.0f };
vgSetfv(VG_CLEAR_COLOR, 4, backgroundColor);
vgClear(0, 0, 640, 360);

painter.endNativePainting();

[rahulvala]

One thing you have to consider if you are comparing N8 and Nokia 500,

N8 has Graphics memory of 32MB , while Nokia 500 does not have.

So, May be this is the possible reason.

[mikpeson]

SpriteBatchQt is now a public project. If you don't want to learn OpenVG but want to target Nokia 500 this project is for you. We will be publishing few example projects that use SpriteBatchQt in few weeks.