Nieminen Juha wrote in message <37e1ea11@news.povray.org>...
>Bob Hughes <inv### [at] aolcom> wrote:
>: I'm not totally inner workings savy, but yes, from what I understand
>: the visible scene is calculated so the other stuff can be dropped out.
>
>  You can't do that. You have no way to know if an object will be visible
>through reflection/refraction (other than actually raytracing the scene).
>If an object was not hit by any ray in the previous frame, you have no way
>to know if it will be hit or not in the current frame.
>  Automatically declaring objects as "static" depending on whether the
clock
>value affects them or not is a mathematically impossible problem (AFAIK).
>You can always write a program which is not analytically solvable.
>Numerical solving would be at least as slow as the actual parsing of the
>scene, so no benefits would be achieved.
>  You can only be sure that an object is not affected by the clock value
>when it doesn't use any identifier which has been "touched" by 'clock'
>(or other identifiers which have been "touched", etc). The same thing for
>'clock_delta'.
>  This is not enought, though. An object may depend on the clock value even
>if it doesn't use any identifier. For example:
>  #if(clock<.5) sphere { 0,1 pigment { rgb 1 } } #end
>
>  But even this is not enough. The object may depend on the contents of an
>external file (which is #read during parsing and which may change from
>frame to frame).


Add a 'static' object modifier to the language that can be applied to
anything, for example:

sphere{<0,0,0>, 1 pigment{ rgb 1} static}

 POV-Ray will not reparse any object that contains that modifier after the
first frame of an animation.  If you apply it to an object that does get
changed over the course of an animation, that's your problem, not POV's.

Mark

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