Performance issues about atc HOT 14 CLOSED

I've never even attempted to optimize it. I'll work on it.

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Good job. I've tried profiling a little, but wasn't nearly proficient enough with the architecture to see an obivous fix. canvas_update_post() came up.

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That's where the entire radar view is drawn. There's no view culling yet. The current bottleneck is drawing the text for each airplane; if I have to, I'll move the text drawing to the DOM, but that's a pretty major change.

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I've vastly reduced redrawing in version 2.1.4; could you test again?

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@joallard What year is your MBA? I'm also playing on an Air and didn't notice any performance-related issues in the prior versions.

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2.1.4: CPU seems to have more breathing space. I think the regular speed has gotten slower though. Might be unrelated.

@jvt Late 2013.

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@joallard, aircraft speed shouldn't change; I just redraw the canvas once every 20 frames or so. They might jump visibly when on higher speed settings, though.

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It may very well just be my perception, caveat emptor, but it feels to me a little more jittery and slowish.

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A significant portion of the time to draw each aircraft - 60-80% using console.time() - is drawing the trailing position dots, not drawing the aircraft itself. This is because canvas_draw_aircraft() saves and restores context and recreates a custom fillStyle and a filled arc - for every single trailing dot for every visible aircraft. This is very slow. I will send a pull request with an idea for a faster method which is visually similar.

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The first picture is the existing aircraft trail, the second is a test of a much faster method (rectangles and fixed opacity).

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And here is a picture of the fast method with variable opacity. Which is the best?
(EDIT: This can be drawn in 1/5 of the time compared to the current method)

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@glangford Nice. This last render looks really good!

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@joallard , @zlsa - With changes #131, #141, #149, #150 I can run now for an extended period without excessive heating or fan use (older Macbook Pro). If there are no objections, I propose this issue can be closed.

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I'm clocking in at 1.5% CPU usage. Good job.

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