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description: Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
items: Widgets and Animation Loops in IDL 5.0
items: Re: Widgets and Animation Loops in IDL 5.0

Widgets and Animation Loops in IDL 5.0
type: item
description: Hi, I am using IDL 5.0 on a DEC Alpha. I am animating a 3D plot of a particle trajectory by incrementing the "az" variable and then replotting in a loop. I decided to add widgets to control the speed of rotation and the angle about the x axis "ax". I have found this to be unworkable so far because once the code enters the loop the widgets do not issue events, so my event handlers do not get called. This was easily fixed by using widget_control commands inside the loop and using sliders to control the speed and x angle, however, I can not find a method to exit the loop, except for possibly adding a slider that could turn it off. The solution seemed to be a toggle button that could be examined using widget_control during the loop, but I have found no way to examine the state of the toggle button. Also while I am at it, I am new to 3D plotting using "plots" to do a trajectory plot. There seems to be no way to get axis on the screen. I have tried the axis command and can only get either one axis, or a white blotch (this seems random as I have not touched that line of code for a while). So help on any of the above will be greatly appreciated. Thank you, Shawn Sent via Deja.com http://www.deja.com/ Share what you know. Learn what you don't.
creator: drphys
date: 1999-07-23T07:00:00-00:00

Re: Widgets and Animation Loops in IDL 5.0
type: item
description: thank you! I believe that this is what I need. Shawn In article <7ng6aq$s6q$1@clam.niwa.cri.nz>, "Mark Hadfield" <m.hadfield@niwa.cri.nz> wrote: > <drphys@my-deja.com> wrote in message news:7na6kq$q9b$1@nnrp1.deja.com... >> Hi, >> I am using IDL 5.0 on a DEC Alpha. I am animating a 3D plot of a >> particle trajectory by incrementing the "az" variable and then >> replotting in a loop. I decided to add widgets to control the speed of >> rotation and the angle about the x axis "ax". I have found this to be >> unworkable so far because once the code enters the loop the widgets do >> not issue events, so my event handlers do not get called. This was >> easily fixed by using widget_control commands inside the loop and using >> sliders to control the speed and x angle, however, I can not find a >> method to exit the loop, except for possibly adding a slider that could >> turn it off. > > Do not use a for or while loop for an animation. Instead, set up your code > so that > each time a frame is drawn, a widget timer event is set with > > WIDGET_CONTROL, TIMER=delay > > (where delay can be zero). Then the widget event handler catches the timer > event, > draws the next frame, and resets the timer, etc. The loop can be terminated > by instructing > the event handler to ignore timer events. This is how CW_ANIMATE does it. > Information about the current state of the animation (current frame, which > direction > we're going in, where the end is & what to do when we get there) can be > stored in a > structure stored attached to one of the widget's UVALUE fields or, better, > in an object. > > I have found object graphics particularly good for animations, and I have > written a > set of animator classes, which illustrate the above technique. > > See my Web page: http://katipo.niwa.cri.nz/~hadfield/gust/software/idl/. > In particular the MGHgrAnimation and MGHgrAnimator classes and the > MGH_EXAMPLE_ANIMATOR routine. But you'll need version 5.2 to run them. > > --- > Mark Hadfield…
creator: drphys
date: 1999-07-26T07:00:00-00:00

Re: Widgets and Animation Loops in IDL 5.0
type: item
description: thank you! This all looks very goood. I will try implementing it later today. Shawn In article <MPG.120253cba46679d7989844@news.frii.com>, davidf@dfanning.com (David Fanning) wrote: > Shawn (drphys@my-deja.com) writes: > >> I am using IDL 5.0 on a DEC Alpha. I am animating a 3D plot of a >> particle trajectory by incrementing the "az" variable and then >> replotting in a loop. I decided to add widgets to control the speed of >> rotation and the angle about the x axis "ax". I have found this to be >> unworkable so far because once the code enters the loop the widgets do >> not issue events, so my event handlers do not get called. This was >> easily fixed by using widget_control commands inside the loop and using >> sliders to control the speed and x angle, however, I can not find a >> method to exit the loop, except for possibly adding a slider that could >> turn it off. The solution seemed to be a toggle button that could be >> examined using widget_control during the loop, but I have found no way >> to examine the state of the toggle button. > > You can look at my XMOVIE program for the proper way to > do an animation in a widget program. It demonstrates how > to write the program so that other events can be processed, > so you can stop the animation, etc. > > http://www.dfanning.com/programs/xmovie.pro > >> Also while I am at it, I am >> new to 3D plotting using "plots" to do a trajectory plot. There seems >> to be no way to get axis on the screen. I have tried the axis command >> and can only get either one axis, or a white blotch (this seems random >> as I have not touched that line of code for a while). So help on any of >> the above will be greatly appreciated. > > Here is an article that shows you exactly how > to do a particle trajectory with axes: > > http://www.dfanning.com/tips/particle_3d.html > > Cheers, > > David > -- > David Fanning, Ph.D. > Fanning Software Consulting > Phone: 970-221-0438 E-Mail: davidf@dfanning.com > Coyote's Guide to IDL Programmi…
creator: drphys
date: 1999-07-26T07:00:00-00:00

Re: Widgets and Animation Loops in IDL 5.0
type: item
description: <drphys@my-deja.com> wrote in message news:7na6kq$q9b$1@nnrp1.deja.com... > Hi, > I am using IDL 5.0 on a DEC Alpha. I am animating a 3D plot of a > particle trajectory by incrementing the "az" variable and then > replotting in a loop. I decided to add widgets to control the speed of > rotation and the angle about the x axis "ax". I have found this to be > unworkable so far because once the code enters the loop the widgets do > not issue events, so my event handlers do not get called. This was > easily fixed by using widget_control commands inside the loop and using > sliders to control the speed and x angle, however, I can not find a > method to exit the loop, except for possibly adding a slider that could > turn it off. Do not use a for or while loop for an animation. Instead, set up your code so that each time a frame is drawn, a widget timer event is set with WIDGET_CONTROL, TIMER=delay (where delay can be zero). Then the widget event handler catches the timer event, draws the next frame, and resets the timer, etc. The loop can be terminated by instructing the event handler to ignore timer events. This is how CW_ANIMATE does it. Information about the current state of the animation (current frame, which direction we're going in, where the end is & what to do when we get there) can be stored in a structure stored attached to one of the widget's UVALUE fields or, better, in an object. I have found object graphics particularly good for animations, and I have written a set of animator classes, which illustrate the above technique. See my Web page: http://katipo.niwa.cri.nz/~hadfield/gust/software/idl/. In particular the MGHgrAnimation and MGHgrAnimator classes and the MGH_EXAMPLE_ANIMATOR routine. But you'll need version 5.2 to run them. --- Mark Hadfield m.hadfield@niwa.cri.nz National Institute for Water and Atmospheric Research PO Box 14-901, Wellington, New Zealand
creator: Mark Hadfield
date: 1999-07-26T07:00:00-00:00