Graphics Enthusiast and Performance Devotee

Gunnar Sletta

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The words and opinions on this page are my own, and not affiliated with any current or former employers.

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Animated Blur for Static Images

Posted by gunnar@sletta.org on October 11, 2014 at 4:05 AM Comments comments (5)

I mentioned before how blurring is a pretty expensive operation so it got me thinking. For dynamic content, we need to do the full thing, and what we have in Qt Graphical Effects is decent, but for static images there are techniques to do it a lot faster.

 

 

We can load images from disk, do a bit of processing, and then be able to dynamically animate from sharp to heavily blurred with close to the same rendering performance as blending a normal image, and with min...

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Looking at Throughput in Qt Quick

Posted by gunnar@sletta.org on October 2, 2014 at 2:35 PM Comments comments (12)

I already talked about the swap test which helps us determine if velvet graphics is indeed possible. The second step I usually take is to benchmark how much graphics we can put on screen before things starts to stutter.


If we focus on pure graphics for now, there are two things worth looking at. Fillrate, which is the systems ability to put pixels on screen; and number of draw call...

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The Swap Test

Posted by gunnar@sletta.org on September 20, 2014 at 4:55 AM Comments comments (2)

This is a test that I usually perform as a first step when encountering a performance issue on a new machine. It establishes whether or not velvet animations are possible at all. It is super simple and works pretty much everywhere. My equivalent of glxgears, you might say. The idea is to show a fullscreen rectangle and alternate the color between red and blue (or any combo of your choice) as fast as swapBuffers() allows. If the visual output is a shimmering, slightly uncomfortable, almost so...

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What is good enough?

Posted by gunnar@sletta.org on September 15, 2014 at 4:10 AM Comments comments (5)

I wanted to start this out with a definition of what is good enough and why. I already covered some of this some time ago here, but I wanted to tidy it up a bit and have it here for completeness, in a framework agnostic fashion.


In real life, objects will move, accelerate and decelerate, but very few things can teleport. So for our brain to perceive natural motion, objects ...

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Qt Graphics and Performance Reboot?

Posted by gunnar@sletta.org on September 7, 2014 at 8:00 PM Comments comments (0)

It has been a couple of years since a few others and I wrote the Qt Graphics and Performance blog series, and I've been contemplating doing a reboot. Both because I've learned a lot since then, and because Qt has a new graphics stack now in Qt Quick 2.0.

Well, I should have some spare time now, so maybe I'll get time to write something...


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