Radar Disk scanning for target, stop


    Mar 31 2006 | 1:43 pm
    Hi everyone,
    This is my first question to the forum so here goes?
    Please find the patch copied and pasted below.
    I have a 3D animation of an object (7207 time,360 frames) rotating. Similar to a radar disk on centre pole scanning for a target. The design is similar to a sucker on a stick with a protrusion on one end that needs to face the viewer when they are picked up by sensors (driven by Basic Stamp 2).
    Basically I am getting it to work i.e. 1. Motor direction either CW or CCW 2. Target i.e. switching between outlet no.1 or 2. When it is on no. 1 it caries on looping and stops on centred time i.e. protrusion facing viewer.
    PROBLEM: it only does this when movie is playing CCW. When turning CW it jumps to centred time instead of rotating and stopping....
    Can anybody help? Their is literarily know body I know working in Cape Town using Max/Jitter and only one person in Johannesburg who teaches it and is not available at the moment. My intuition tells me if one can swap current time and centred time around in outlet no.1 when it is playing CW it will work?
    Alternatively maybe one does not have to make use of loop points at all? What I tried to do as alternative is e.g. ?select 350? from current frame count i.e. frame to be stopped at a certain number combined with a switch. When target = 0 it will just continue looping. When target = 1, switch will stop movie at number coming from select.
    The problem with this approach is that it sometimes does it and sometimes not i.e. frame rate is too fast to always be recognised by the select number in order to send stop message?
    Any help, advice will be appreciated. Please bear in mind that I am a VERY novice Max/Jitter user.
    Regards, Johann ------------------------

    • Mar 31 2006 | 8:44 pm
      On Mar 31, 2006, at 5:43 AM, Johann wrote:
      > > Can anybody help? Their is literarily know body I know working in > Cape Town using Max/Jitter and only one person in Johannesburg who > teaches it and is not available at the moment. My intuition tells > me if one can swap current time and centred time around in outlet > no.1 when it is playing CW it will work? > > Alternatively maybe one does not have to make use of loop points at > all? What I tried to do as alternative is e.g. ?select 350? from > current frame count i.e. frame to be stopped at a certain number > combined with a switch. When target = 0 it will just continue > looping. When target = 1, switch will stop movie at number coming > from select.
      I would recommend that you avoid using loop points for this type of rapidly changing dynamic behavior and explicitly set the output frame with the frame message to jit.qt.movie. This is more flexible and less prone to some of the odd QT behavior when chaning playback speed and looppoints dynamically (this is pretty much out of our control and dependent on the QT implementation).
      As previously mentioned on the list, I would suggest in such a case to drive the animation using a cpuclock based solution. Perhaps someone else on the list has such an example of dynamic looping with cpuclock and the frame message. I know that Andrew B just posted a variant on the Jitter recipes page which doesn't have the advantage of cpuclock, but demonstrates the fundamental concept. The use of cpuclock is to use "wall time" to determine movie time which will make the animation seem to have consistent playback speed despite the fluctuating framerates of realtime processing.
      Hope this helps.
      -Joshua
    • Apr 01 2006 | 10:56 am
      Dear Josua,
      Thanks for the reply.
      > cpuclock and the frame message. I know that Andrew B just posted a > variant on the Jitter recipes page which doesn't have the advantage > of cpuclock, but demonstrates the fundamental concept. The
      I briefly looked at Andrew B's recipe page I don't know which specific recipe you are referring to. If you can be so kind to tell me wich oine I will download it and start experimenting from there.Sorry to be so ignorant but this is completely new ground for me.
      One more question: would you recommend I post a new message specifically asking for an example path to drive the animation using a cpuclock-based solution i.e. as you suggested example of dynamic looping with cpuclock and the frame message. Since this is the first time I am making use of the forum I don?t want to go against the forum etiquette.
      Regards, Johann
    • Apr 01 2006 | 2:41 pm
      Dear Josua,
      You are a STAR!
      > I would recommend that you avoid using loop points for this type of > rapidly changing dynamic behavior and explicitly set the output frame > with the frame message to jit.qt.movie. This is more flexible and
      I followed your advice, avoiding loop point, and got it to work! Thanks for pointing me in the correct direction. See new patch below.
      > As previously mentioned on the list, I would suggest in such a case > to drive the animation using a cpuclock based solution. Perhaps
      HOWEVER, I did it without using "cpuclock" instead "massaging the numbers" by dividing the current time by a 100 units in order to get a smaller number. It works, but it does not stop at exactly the same number each time because it is in effect now a range of numbers.
      I am trying to figure out how to use "cpuclock" to get a more accurate stop. If you can get advice if it will provide a more accurate stop time and how I can possible incorporate it into current patch it would be great.
      Regards, Johann
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