Although the tips in the following link are only concerning DirectX9, it may still be useful in Qt:
- Only redraw to the image buffer when you need to
- Use smaller textures
- Draw objects from front to back
- Constantly test your code’s performance
- Use one large array/buffer of vertices
- Draw only what needs to be drawn, so culling and z-ordering can only help more
The ideal is to get a higher framerate which is perceivably better experience for the user. For 2D graphics, 16 frames per second is satisfactory. But for 3D graphics, 30 frames per second seems to be tolerable, but 60 frames per second is the minimal. But if you’re just learning 3D graphics programming, don’t worry about frames per second, just worry about the geometry and math to make sure it is correct. Then you can optimize it when you’re confident you understand how it all works.
For many Qt lovers out there who might want to use third-party EXIF parsing library with their Qt apps, it may prove difficult unless you know what you’re doing. If you’re a hobbyist like me, man, it’s just tough. But there are free EXIF parsers out there, and it might take a little elbow grease to make it work with Qt. In my case, I put together a very simple and basic image viewer that I thought users might appreciate if it auto-rotated any images that contained EXIF metadata such as orientation. In smartphones and DSLRs, there is usually a sensor that records which orientation the picture was taken in. So when you view the photo without orientation applied, it might be a minor nuisance having to manually rotate it. That’s where you come in as software developer and take care of it for the end-user. Continue reading “How To Read EXIF Orientation From JPEG in Qt 4.8.5”
If you thought Qt provided you with a robust count of math algorithms already, you’ll be in for a surprise. There is
qrand(), but it doesn’t quite provide you with the user-friendliness of other languages. For example, sometimes you want a random number that is negative. Sure, you can do this all manually, but then you’d have to write your own function. Unfortunately, that’s exactly what you’ll have to do.
int QMyClass::randInt(int low, int high)
// Random number between low and high
return qrand() % ((high + 1) - low) + low;
// Create seed for the random
// That is needed only once on application startup
QTime time = QTime::currentTime();
// Get random value between 0-100
int randomValue = randInt(0,100);
It is recommended that you don’t use
qrand() by default if you want to generate encryption-level random numbers.
So, with that code, now you can set a range of numbers which you can pull random numbers from. Make note that qsrand() only sets the seed and you should only do that once.