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Vector Tanks Game In App Store -- How Do They Do It? - Printable Version

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Vector Tanks Game In App Store -- How Do They Do It? - kalimba - Mar 25, 2009 04:27 PM

Has anyone seen or played the Vector Tanks game in the App Store? An someone who was addicted to Battlezone in the arcade (long ago, in a former life Smile), I can say that the game author(s) have done a terrific job achieving the look of those early Atari vector displays. The "vectors" they are drawing appear to be anti-aliased and have the same "glow" style that you'd expect from a real vector display.

Any ideas how they're pulling this off? Could it be just plain old GL line primitives? Perhaps multiple passes applying some effect to achieve the halo/glow?


Vector Tanks Game In App Store -- How Do They Do It? - demonpants - Mar 25, 2009 04:39 PM

It's possible they're just binding a glow texture that has fade before they draw a triangle fan representing each line. So basically it'll end up being a bunch of stretched sprites. They could also just be drawing multiple lines with more and more transparency, making the same glow fadey effect. OpenGL is pretty good at optimizing a lot of line and texture calls so I wouldn't be surprised if it could work on a simple level like that.


Vector Tanks Game In App Store -- How Do They Do It? - bmantzey - May 15, 2009 09:52 AM

It could also be the blend mode.


Vector Tanks Game In App Store -- How Do They Do It? - arekkusu - May 15, 2009 10:06 PM

Draw textured quads.