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 CAD / Ray-Tracing / 2444
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Subject: 
Re: My humble opinion about LDraw animation
Newsgroups: 
lugnet.cad, lugnet.cad.ray, lugnet.animation
Date: 
Wed, 24 Aug 2005 18:12:17 GMT
Viewed: 
247 times
  
In lugnet.cad, Steve Bliss wrote:
In lugnet.cad, Damien Guichard wrote:
Before i attempt anything i will now carefully consider:
* what POV-Ray can do
* how it does
* whether i can do easier/better

I mostly agree with James (use POV-Ray for animations), but I'll throw my 2
cents in anyway ...

It seems like an LDraw-based animation format is reasonably possible, with the
following requirements/additions:

- Use MPD format.  This isn't totally required, but as James has documented, it
is a Very Good Idea.
- Support the LDLite language extension.  This includes meta-statements such as
ROTATE, TRANSLATE, SCALE, POINT, and MATRIX, and enhanced syntax to use defined
POINTs and MATRIXs in normal LDraw statements.
- Some concept of variables and expressions.
- A Timer system variable
- An ANIMATE meta-statement, giving the paremeters to control the animation.
- An IF/END IF block meta-statement.  This would be important for any animation
other than very simple single-action animations.

OK, that list is longer than I thought it would be.  But most of the items on
the list are relatively straightforward to implement.  At least, they are well
known and well-solved programming problems.  The code to support LDLite language
can be gotten/adapted from the ldglite source code.  That gives a base for block
statements and variables.  Parsing/interpreting expressions is a common
scripting challenge, the logic/code should be available somewhere.

A program to process such a script could take an animation (.LDA?) source file
as input, and generate a standard LDR file (or series of files) for output.
We've already got programs that can render images, no need to reimplement that.

The key-frame processor suggested by Orion-2 is interesting, but sounds harder
to implement...

Steve

Unfortunately, I am very busy right now. Once again, I have to move and it sure
takes its toll from my resources.

But I'd like to repeat what I've said earlier on creating LDraw based
animations. We have LD4D, we have POV-ray's support for animations, we have the
abandoned LANI project, and we have my LDA2001. As its name suggests, it's been
on ice since 2001. I tried to restart the project earlier this year, but failed
due to lack of time and energy.

There are advantages and drawbacks with all of the choises. LD4D had a very
professional feel, but all the newer versions have crashed at start on my PC:s.
Also, it seems to have a very high learning threshold at the first step. I may
be wrong at this - hopefully.

So far, we haven't seen anything useful (IMHO) in using POV's own animation
engine, but its support for math's functions is undoubtly a very strong
advantage. Some kind of MPD with animation METAs, run through a special L3P-like
program might do the trick!

But if I ever get the time to, I lean towards keep deveoping my own LDA2001,
even though it needs a total rework. It is the only easy-to-use animation system
that really works today IMHO. Anyone with a windows PC, the LDraw package, L3P,
and POV can make an animation with one or more minifigs walking using LDA2001.
But, like I said, LDA needs a total rework with support for .LDR, new minifig
parts, and many, many other things. Yet, it does work, which means that my
system is a workable way, while the other ways have yet to prove that.


/Tore
(I do really hope to get more time for LDraw based animations after September
15th, when my moving must be done...)



Message has 2 Replies:
  Re: My humble opinion about LDraw animation
 
It appears from this discussion that methods already exist, its just that they are not particularly easy to use or accessible. Whatever solution we choose, we need to think about usability. I am a developer, and even I dont like having pull things (...) (19 years ago, 25-Aug-05, to lugnet.cad, lugnet.cad.ray, lugnet.animation)
  LDraw animation: Camera.dat and Look_at.dat  [DAT]
 
One more thing: I will use CAMERA.dat and LOOK_AT.dat in each Frame file in my planned LDA (hopefully LDA2005...). I find them very handy, anyone can use them and move them around in MLCad or whatever LDraw editor. This is how I made them, but (...) (19 years ago, 28-Aug-05, to lugnet.cad, lugnet.cad.ray)

Message is in Reply To:
  Re: My humble opinion about LDraw animation
 
(...) I mostly agree with James (use POV-Ray for animations), but I'll throw my 2 cents in anyway ... It seems like an LDraw-based animation format is reasonably possible, with the following requirements/additions: - Use MPD format. This isn't (...) (19 years ago, 24-Aug-05, to lugnet.cad)

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