Thoughts on animation scripting language

[Roland Melkert]

I haven't used LDCad, so forgive me if any of this misses the point. I haven't used it because I'm very experienced with my existing setup (MLCad -> LDView -> PovRay), because I don't presently have the time to investigate it, and because LDCad looks a little too "heavy" for my aging PC :-)

Don't worry about it.

...Using this technique not only can I easily manipulate the position of parts and the camera, but I can also programatically generate sequences whereby parts become hidden or unhidden on a frame-by-frame basis...

Access to visibility will also be possible, as lua gets full control over the associated group of ldraw parts, I might even let the user manipulate the individual parts inside the group or whole model not sure about that yet.

... thus automatically generating a brick-by-brick build animation of an entire model regardless of whether the model is flattened first or left in a sub-model/structured state...

The current LDCad version supports editing a multi file model at the top level as if it were a single flat model, it's called the nesting mode. While this mode is active you can also create groups out of parts living in different files. It will be those groups you can manipulate (realtime) using LUA scripts during a special animation mode.

... example http://www.youtube.com/watch?v=Aj4AUgJApys). I also use this technique to assist in automatically disabling sub-models which are not visible within specific ranges of frames (or still renders) in order to reduce the memory footprint and speed up the render times.

Great animation

The example script you gave is in fact very similar to the code I inject into the .pov file for cyclic animations, so for someone of my skills I feel you are going about this the right way. The choice of language matters more to the developer than the end user, as long as it has access to stuff like sin/cos/tan/asin/acos/atan/sqrt and preferably also inbuilt functions for splines and beziers.

fun thing about LUA is you can get additional stuff from else where, but I will be supplying built-in functions for most logical LDraw / animation related things. And I could always add things upon request.

It's clearly too complex for a non-programmer, but in my experience those type of people would only attempt an animation if they had some sort of simple "wizard" to generate the script or animation sequence for them

You are right about that, the reason I'm only going to do the scripting route is because my full GUI animation software (LD4DStudio) was still considered to hard by most, so I simply won't even implement the 'easy' way. But supplying wizards at some point is a good idea, I might even be able to make those plugin based so others could add them for me

...One thing I would like to say about that example script. Your example uses relative position calculations on each frame. That's fine, for many cases. But I've found that in most of my cases I prefer the ability to perform absolute calculations based upon PovRay's frame_number.

Yes in the example it's relative, but it won't be limited to that. The two main functions will have no or very little parameters, but things like frame rate and current frame etc will be accessible through global functions/variables. Also the script won't be exclusive for just animation, it will also be possible to use them for 'action response' e.g. the user spins an axle in the model, all the rest moves based on script calculations.

The other thing that is unclear to me is what LDCad would be outputting here. Are you going to output a new unique .mpd for every frame and leave it to the user to convert these to a format suitable for raytracing?

The first goal is realtime animation inside LDCad it self, but later on I want to offer export to multiple mpd's / pov-ray simular to the export functionality of LD4DStudio.



Thanks for you thoughts on the issue.