Hello,

I want to use mechsim to place spheres in a still image. So far I'm able to
produce an animation that moves the spheres in the scene and generates a new
sphere in each frame (derived from tutorial03.pov). For my still image, I only
need the last frame of course.

How can I make mechsim iterate over a given number of "frames" (of which no
images should be generated to save time) and let megapov render the resulting
scene (ie, last frame only)?

Regards,
Boris

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"borix" <nomail@nomail> wrote:
> Hello,
>
> I want to use mechsim to place spheres in a still image. So far I'm able to
> produce an animation that moves the spheres in the scene and generates a new
> sphere in each frame (derived from tutorial03.pov). For my still image, I only
> need the last frame of course.
>
> How can I make mechsim iterate over a given number of "frames" (of which no
> images should be generated to save time) and let megapov render the resulting
> scene (ie, last frame only)?
>
> Regards,
> Boris


http://www.povray.org/documentation/view/3.6.1/216/

2.1.2.1.3 Subsets of Animation Frames

Hope this helps

Leef_me

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> http://www.povray.org/documentation/view/3.6.1/216/
> 
> 2.1.2.1.3 Subsets of Animation Frames
> 
> Hope this helps

I think it won't. The way MegaPOV mechsim works for animations is by 
loading the simulation data from disk, processing it some more, saving 
it back, and rendering. If you render only the last frame, it would look 
like the first frame...

There must be a way to do it with megapov settings on the mechsim block, 
but I have never used it. I only rendered the sample scenes using mechsim :)

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Nicolas Alvarez <nic### [at] gmailisthebestcom> wrote:

> > http://www.povray.org/documentation/view/3.6.1/216/
> >
> > 2.1.2.1.3 Subsets of Animation Frames
> >
> > Hope this helps
>
> I think it won't. The way MegaPOV mechsim works for animations is by
> loading the simulation data from disk, processing it some more, saving
> it back, and rendering. If you render only the last frame, it would look
> like the first frame...

That's right. mechsim doesn't work if you don't start the animation from the
beginning. This is what happens with a new file:

> megapov +sf150 +ef200 +kff1000-j l msim.pov

....

  0:00:01 Calculating Mechanics Simulation Time=0.0000s (0 percent)
File: msim.pov  Line: 58
File Context (5 lines):
                                save_file "coords.dat"
                        }
                #end
        }
Parse Error: Attempt to malloc zero size block (File: mechsim.cpp Line: 4420).


Rendering with +sf ... +ef works if there's a MSIM *.dat-file, but then mechsim
just continues where it previously ended.

I use -w1 -h1 to speed up rendering. I haven't found a more clever way yet.

-Boris

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> Parse Error: Attempt to malloc zero size block (File: mechsim.cpp Line: 4420).

Considering the text of that message, it looks like a BUG on MegaPOV.

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"borix" <nomail@nomail> wrote:
....
> That's right. mechsim doesn't work if you don't start the animation from the
> beginning. This is what happens with a new file:
....
Run your simulation to the point you want, data is saved with the save_file
option.
Edit your Megapov file to only load_file your data.
When you run the file now you should get only the last simulation frame.

StephenS

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"StephenS" <nomail@nomail> wrote:
> Run your simulation to the point you want, data is saved with the save_file
> option.

But then I still have to render the first n-1 pictures?

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"borix" <nomail@nomail> wrote:
....
> But then I still have to render the first n-1 pictures?
Choose a larger step_count?

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"StephenS" <nomail@nomail> wrote:
....
> Choose a larger step_count?
And lower the number of frames in the animation :-)

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As in tutorial03.pov, I introduce a new mass in every frame. Therefore,
increasing step_count doesn't help.

I circumvented the problem by placing a large number of masses in the scene to
start with.

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