I have a simple spline set up which I was hoping to use for camera work...
Now the stuff in the while loop works, but the Camera_Location declaration
doesn't (this is used later to set the camera's location)

Upon parsing this, I get the error:
File: D:\Mark\Pov-Ray\projects\bug\bug.pov  Line: 270
  #declare Camera_Location1 = Camera_Path <----ERROR
Parse Error: Cannot copy identifier


//snip
  #local Cam_Start = <-60, 70, -70>;
  #local Cam_CockpitWindow = <-43.5, 34.5, -6.5>;
  #declare Camera_Path=
    spline{
      natural_spline
      -1, Cam_Start+(100*x)
       0, Cam_Start
       1, Cam_CockpitWindow
       2, Cam_CockpitWindow+(100*x)
    }

  #local i=0; #while (i<1)
    sphere{Camera_Path(i), 0.2 pigment{color rgbt <1,1,0,0.8>}}
  #local i=i+0.03; #end

  #declare Camera_Location = Camera_Path(0); //Camera_Path(clock);
//snip


I assume it's something daft, but I haven't spotted it :(

--

Mark Hanford
http://www.mrhanford.com/povray

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Why can I do
#debug vstr(mySpline(pos), ...)

or
camera{ location mySpline(pos) ...}

but not
#declare MyVar = mySpline(pos);

???
thanks

--

Mark Hanford
http://www.mrhanford.com/povray


"Mark Hanford" <ren### [at] blueyondercouk> wrote in message
news:3c94f7cc@news.povray.org...
> I have a simple spline set up which I was hoping to use for camera work...
> Now the stuff in the while loop works, but the Camera_Location declaration
> doesn't (this is used later to set the camera's location)
>
> Upon parsing this, I get the error:
> File: D:\Mark\Pov-Ray\projects\bug\bug.pov  Line: 270
>   #declare Camera_Location1 = Camera_Path <----ERROR
> Parse Error: Cannot copy identifier
>
>
> //snip
>   #local Cam_Start = <-60, 70, -70>;
>   #local Cam_CockpitWindow = <-43.5, 34.5, -6.5>;
>   #declare Camera_Path=
>     spline{
>       natural_spline
>       -1, Cam_Start+(100*x)
>        0, Cam_Start
>        1, Cam_CockpitWindow
>        2, Cam_CockpitWindow+(100*x)
>     }
>
>   #local i=0; #while (i<1)
>     sphere{Camera_Path(i), 0.2 pigment{color rgbt <1,1,0,0.8>}}
>   #local i=i+0.03; #end
>
>   #declare Camera_Location = Camera_Path(0); //Camera_Path(clock);
> //snip
>
>
> I assume it's something daft, but I haven't spotted it :(
>
> --
>
> Mark Hanford
> http://www.mrhanford.com/povray
>
>
>
>

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In article <3c950d0c@news.povray.org>,
 "Mark Hanford" <ren### [at] blueyondercouk> wrote:

> Why can I do
> #debug vstr(mySpline(pos), ...)
> 
> or
> camera{ location mySpline(pos) ...}
> 
> but not
> #declare MyVar = mySpline(pos);

POV-Ray's parser (currently) isn't smart enough to figure out whether 
you want a copy of mySpline or a point on it. In the other two examples, 
it knows you are using vectors. Try this instead:
#declare MyVar = (mySpline(pos));
The parentheses get POV to treat it as a numeric expression, so it 
evaluates the spline instead of trying to copy it.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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Wasn't it Mark Hanford who wrote:
>Why can I do
>#debug vstr(mySpline(pos), ...)
>
>or
>camera{ location mySpline(pos) ...}
>
>but not
>#declare MyVar = mySpline(pos);
>
>???
>thanks

I thought I remembered doing that sort of thing all the time, but it
turned out that I wasn't using raw splines, I was using spline functions

   #declare Camera_Path= 
   function {
     spline{
       natural_spline
       -1, Cam_Start+(100*x)
        0, Cam_Start
        1, Cam_CockpitWindow
        2, Cam_CockpitWindow+(100*x)
     }
   }

  #declare Camera_Location = Camera_Path(0); //Camera_Path(clock);

-- 
Mike Williams
Gentleman of Leisure

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Isn't that a bug?
Surely these shouldn't be considered identical:
#declare myVar=mySpline //makes myVar a spline{}
#declare myVar=mySpline(32) //makes myVar equal <1,2,3>


--

Mark Hanford
http://www.mrhanford.com/povray


"Christopher James Huff" <chr### [at] maccom> wrote in message
news:chr### [at] netplexaussieorg...
> In article <3c950d0c@news.povray.org>,
>  "Mark Hanford" <ren### [at] blueyondercouk> wrote:
>
> > Why can I do
> > #debug vstr(mySpline(pos), ...)
> >
> > or
> > camera{ location mySpline(pos) ...}
> >
> > but not
> > #declare MyVar = mySpline(pos);
>
> POV-Ray's parser (currently) isn't smart enough to figure out whether
> you want a copy of mySpline or a point on it. In the other two examples,
> it knows you are using vectors. Try this instead:
> #declare MyVar = (mySpline(pos));
> The parentheses get POV to treat it as a numeric expression, so it
> evaluates the spline instead of trying to copy it.
>
> --
> Christopher James Huff <chr### [at] maccom>
> POV-Ray TAG e-mail: chr### [at] tagpovrayorg
> TAG web site: http://tag.povray.org/

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In article <3c95da20$1@news.povray.org> , "Mark Hanford" 
<ren### [at] blueyondercouk> wrote:

> Isn't that a bug?

No.

Also note this is common in typeless languages.

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

I was confused by the manual
"To use a spline, you place the spline identifier followed by the parameter
(in parentheses) wherever you would normally put a vector, similar to a
macro. Splines behave exactly like three-dimensional vectors"

So apparently not quite like a macro or vector, after all...

--

Mark Hanford
http://www.mrhanford.com/povray


"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3c95e01b@news.povray.org...
> In article <3c95da20$1@news.povray.org> , "Mark Hanford"
> <ren### [at] blueyondercouk> wrote:
>
> > Isn't that a bug?
>
> No.
>
> Also note this is common in typeless languages.
>
>     Thorsten
>
> ____________________________________________________
> Thorsten Froehlich
> e-mail: mac### [at] povrayorg
>
> I am a member of the POV-Ray Team.
> Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message