How to time v3f, etc. (was: n3f v3f timing)

Paul Martz pmartz at undies.dsd.es.com
Tue Apr 30 03:32:54 AEST 1991


In article <1991Apr29.154346.6866 at odin.corp.sgi.com>, kurt at cashew.asd.sgi.com (Kurt Akeley) writes:
> The n3f/v3f calls block only until the vector data have been copied from
> your data space, not until the drawing commands have actually been
> completed.  Typically the data are copied to the head of a several hundred
> word fifo, which tail is connected to the graphics hardware.

Suppose I'm trying to time my performance. Let's say I get the current
clock time in milliseconds, then I send down several bgnpoly()'s,
v3f()'s, and endpoly()'s. Then I get the clock time in milliseconds
again, subtract it from the start time, and divide by the number of
polygons.

What have I just timed? Have I timed copying data to a fifo, or have I
timed the actual drawing? Does calling endpoly() block until the fifo
is empty? If not (and I hope not), what gl function can I call which
will? (swapbuffers() wouldn't be what I'd want, because I don't want
buffer swaps included in the timing.)
-- 

   -paul	pmartz at dsd.es.com
		Evans & Sutherland



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