A blog about software – researching it, developing it, and contemplating its future.

Archive for February 2013

Goodbye XNA, helloooo SharpDX

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Half a year ago I posted about my XNA dilemma, and about how SharpDX looked like the best replacement. XNA = old and busted C# DirectX library from Microsoft, now officially kicked to the curb; SharpDX = amazing generated-from-C++-DirectX-sources open source C# binding to the entire DirectX API, which is waaaaay more than XNA ever did.

Last summer I was a bit daunted by SharpDX, as the API was not very XNA-like. Alex Mutel, the primary author of SharpDX, said he was working on an XNA compatibility layer but it wasn’t ready yet. I then figured out how to get multiple window support (the primary driver at the time) working with XNA, so I set SharpDX aside for a while.

Well, Alex was as good as his word. After a fair amount of very entertaining Holofunking over the holidays (Holidayofunking?), I finally decided that with the new year would come a new 3D library underneath Holofunk. And what do you know, the SharpDX Toolkit library was ready.

Over the course of a couple of weeks, working relatively infrequently and in small chunks, I converted everything off of XNA. If you want to see a reasonably small, but realistic, XNA-to-SharpDX conversion in full, you could do a lot worse than looking at this changelist on CodePlex.

First of all I realized there was no multi-window support in SharpDX. Well, that’s fine, I posted an issue about it and offered to help with the implementation. Alex immediately responded and asked for a short while to build some support pieces. The next thing I knew (three days later), he’d implemented the whole feature. It worked fine for me the first time.

The most surprising changes were:

  • In XNA, the Rectangle constructor takes (int left, int top, int width, int height). In SharpDX, it takes (int left, int top, int right, int bottom). This led to all KINDS of amusing weirdness.
  • The Point type is gone, so I switched to Vector2 with some casting to int. Probably there is a better way but I don’t yet know it.
  • The XNA Color.Transparent is equivalent to Color(0, 0, 0, 0) — e.g. premultiplied black at zero alpha. In SharpDX, it is Color(0, 0, 0, 255) — e.g. black with full alpha. Everywhere I had been using Color.Transparent I switched to “new Color(0)” to get the same effect in SharpDX.
  • In XNA, the Color constructor takes (int r, int g, int b, int a). In SharpDX, it takes either (byte r, byte b, byte g, byte a) or (float r, float g, float b, float a). This caused some of my color math to use the float overload rather than the byte overload, with ensuing hilarity.
  • I ran into a premultiplied alpha problem with PNGs, which aren’t premultiplied. I posted an issue and Alex responded immediately AGAIN. I was able to hack around it with his suggested BlendState.NonPremultiplied workaround.
  • I tried using 32-bit premultiplied BMPs in RGBA format, but ran into ANOTHER issue, which, of course, I posted. We’ll see whether Alex maintains his exemplary responsiveness.

If you’re getting the idea that Alex is incredibly helpful, you’re right. He’s right up there with the excellent authors of the BASS audio library, about whom I’ve similarly gushed. The very best open source projects to use in YOUR open source project are the ones with active and helpful maintainers. And having an open source project of your own really helps get support, since you can show your code and they can point others at your code as an example of something cool done with their work.

So now Holofunk is fully running on SharpDX with all features maxed, multiple window and two-player support, and much faster rendering. It looks pretty much the same, but now all obstacles to video texturing, bizarre postprocessing, Fourier transforms on the GPU, etc., etc., are removed. The sky is now the limit.


Next up: sound effects! At last!

Now that I’ve gotten that big move over with, it’s time to start putting sound effects in at last! I bought a copy of Sugarbytes Turnado, the VST plugin Beardyman uses in his live rig, and it is indeed friggin’ amazing. Been having all kinds of fun exploring it.

The tricky part is that it does eat CPU, and I’m not sure how many instances of it I will be able to create with the BASS audio library I’m using. So while part of me wants an interface that lets me apply any random set of effects to each and every individual loop, that would mean one instance of Turnado per loop. In Holofunk it’s easy to create dozens of loops. So I needed some fallback story for how to manage sound effects in some more granular way.

I think what I will try first is splitting the screen into eight wedges (instead of the four quarters in the current version), with each wedge having its own instance of Turnado. So all loops in a given wedge will share a set of effects. It will be possible to select multiple wedges and wave your arms wildly to wiggle the Turnado knobs for all those wedges at once. It will also be possible to record animated knob-wiggling across a set of wedges. That, combined with effect selection, should be more than enough to get some serious madness going on, while being pretty straightforward to implement.

I also have an interesting idea for a graphical interface for scratching, but I’m going to show that one in prototype form rather than blog about it 🙂

Meanwhile, Elsewhere In Loopania wins the big Looping Journalism Award of the last two months. They have an excellent and long article on Beardyman’s new live performance setup, which he said on Facebook will be coming soon to a TED talk near you. CAN NOT WAIT.

They also have a video of Imogen Heap with the latest iteration of her gestural music gloves. Here’s the video for your convenience — and look, she’s got a Kinect in there!

How ridiculously cool is THAT???

This entire field of musical experimentation is moving along most awesomely, and I’m greatly enjoying my own little part in it.

So: February is the month of Sound Effects Into Holofunk. March I plan another round of beta testing, aka getting together with my Holofunk posse and partying on it. April and May, more work, and then into demo season in June with a public performance at the Maker Faire. Going to try to be ready for a 30-minute gig this time!

Expect another update in March or so. Until then, stay funky!

Written by robjellinghaus

2013/02/07 at 00:27

Posted in Holofunk