July 30, 2014 | Filed under: gsb2 | programming008
So I was tweeting that this took forever:
It’s just a dialog box for gratuitous space battles 2., why did it take more than twenty minutes to put together? Now… I’ve seen unity, I know it has all these plug-ins that do stuff like this, and that it’s all very user-friendly etc blah blah. But I’m old school. I’m rocking my own custom-written engine, including all the GUI. That gives me huge advantages (mostly speed) and also some disadvantages. The best advantage is there isn’t anything I can’t make the code do.
The pain with this dialog box came in three flavours.
Flavour one was those circular clock-like indicators. In theory, this is really easy, you can just generate a tri-strip of a lot of polygons and draw a curve thats smooth and crisp as you like, as long as you can spare the vertexs. I’m not drawing many, so it’s not an issue. The problem is, when you do that, you get a too-blocky, too un-aliased clunky mess that just doesn’t look ‘right’ when surrounded by lovely aliased everything. I’m not drawing 3D models, so my game has a nice smooth look to it, and it jarred badly. So I have a sprite of that curve, and I draw a subset of it using a tri-strip arc. It’s a bit fiddly, ant took a while to get right.
Flavour two was the outline of the right-hand part of the window. It’s a bit complex, as it goes in and out and then around the close button and then loops around those circles, and it has to be really slick too, and ironically in this case it looks better drawn as a crisp 1 pixel line, so there is actual hand-crafted code in there to work out all those positions and curve ncie arcs and lines around them.
Flavour three was speed. I like everything in my game to render fast, including GUI. No point in having a fast engine where 95% of the frame is spent drawing a dialog box. That means ensuring that ouline on the dialog is a single draw call with no fuss, that all those tiny animated bits of fluff in the dialog corners and outside the edges are drawn efficiently, that the calculations on that arc outline are as fast as possible, and that the dialog in general; doesn’t use many draw calls.
It’s all horribly, laughably slow really. I probably have a ‘spare render target’ knocking about that I could use to blap this whole dialog to (BTW they resize dependent on the ship, which adds to the complexity), and then only update it when it changed, otherwise just blapping it as a single quad. In practice, the windows various elements update quite a bit.. but I’m sure I could speed up the module icon rendering with runtime aliasing onto spare render targets. I love all this stuff.
But even I know when I’m getting obsessed and need to move on!