Re: frame rate control with IRIX 5.3
John Rohlf (jrohlf++at++tubes)
Fri, 10 Mar 95 18:32:27 PST
>
> Hello,
>
> This is a follow-up to the problem I was having with frame rate control on my
> Indigo2 with IRIX 5.2/Performer 1.2 (case ID 0338219). I installed IRIX5.3 on my
> Indigo2 and I do now, in fact, have frame rate control in my Performer 1.2
> application. However, there is another "feature" that has apparently been
> introduced which, unless I'm doing something wrong, makes the fix a little less
> satisfying than I had hoped for. The problem is this: using a pfPhase of FLOAT
> or LOCK, the application runs at the frame rate specified by pfFrameRate just
> fine until, say, it has to draw a lot of terrain, for example, such that it
> can't get done in the specified time frame. When this happens, instead of the
> frame rate slowing down to whatever it takes to complete the drawing, the frame
> rate gets cut to half its specified rate. For example, in my application I
> specify a frame rate of 12 HZ and if I get to a point that everything can't get
> drawn that fast, the frame rate gets cut to 6 Hz. This is only a problem with
> PFPHASE_FLOAT and PFPHASE_LOCK. When I tried running with PFPHASE_FREE_RUN, the
> same application drawing the same terrain runs at from 10Hz to 14Hz, varying as
> different objects come into or go out of view. This causes me problems because
> my application "flies" over large areas of terrain and I need it to "run out of
> time" a little bit every now and then without the very noticeable slowdown of
> running at half speed. Does anyone out there know what this is?
>
> Thanks
>
> Jim Beaver
> Smiths Industries - Defense Systems North America 616-241-7671
> beaver_jim++at++si.com
>
>
Single process fixed frame rate is kind of a dicey prospect
since you don't have the flexibility of the APP maintaining a fixed
rate while the DRAW skips frames if it overruns. You can try
PFMPAPP_CULLDRAW + FLOAT even on a single process machine or you can
try PFPHASE_LIMIT which is the same as FREE_RUN but ensures you go
no faster than your specified frame rate.
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on Mon Aug 10 1998 - 17:51:03 PDT