Not arguing against it - but from work I've done in the past I doubt very much that accurately colored tracers could be implemented on a computer screen.
In real life, a blue hued tracer could be seen against the blue sky, because it was many times brighter than the ambient light, and a green hued tracer against the ground. On a computer screen, blue is blue and green is green and there isn't a way to brighten the tracers to much beyond the levels already in use to paint the ground and sky, so they'd tend toward the invisible unless you were viewing them against a contrasting color.
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As moot stated - pixel shaders solve this problem.
IL2 did it with zero difficulty years ago.